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Building Construction Handbook Eighth Edition PDF Book

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Summary of Contents

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    BUILDING CONSTRUCTIONHANDBOOK

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    BUILDINGCONSTRUCTIONHANDBOOKEighth editionR. ChudleyandR. GreenoAMSTERDAM . BOSTON . HEIDELBERG . LONDON . NEW YORK . OXFORDPARIS . SAN DIEGO . SAN FRANCISCO . SINGAPORE . SYDNEY . TOKYOButterworth-Heinemann is an imprint of Elsevier

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    Butterworth-Heinemann is an imprint of ElsevierThe Boulevard, Langford Lane, Oxford OX5 1GB, UK30 Corporate Drive, Suite 400, Burlington, MA 01803, USAEighth edition 2010Copyrightª 1988, 1995, 1996, R. Chudley.Copyrightª 1998, 2001, 2004, 2006, 2008, 2010, R. Chudley and R. GreenoPublished by E...

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    CONTENTSPreface to eighth editionxiPart OneGeneralBuilt environment2The structure5Primary and secondary elements12Component parts and functions15Construction activities19Construction documents20Construction drawings21Building survey28HIPs/Energy Performance Certificates32Method statement and prog...

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    Materials storage101Materials testing106Dry and wet rot121Protection orders for trees and structures123Locating public utility services124Setting out125Levels and angles129Road construction132Tubular scaffolding and scaffolding systems140Shoring systems153Demolition162Part ThreeBuilders PlantGene...

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    Part FiveSuperstructure† 1Choice of materials322Brick and block walls323Cavity walls338Damp-proof courses and membranes344Gas resistant membranes351Calculated brickwork353Mortars356Arches and openings359Windows366Glass and glazing379Doors391Crosswall construction400Framed construction404Renderi...

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    Long span roofs569Shell roof construction579Membrane roofs588Rooflights590Panel walls594Rainscreen cladding600Structural glazing602Curtain walling603Concrete claddings607Concrete surface finishes614Concrete surface defects616Part SevenInternal Construction and FinishesInternal elements618Internal...

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    Part EightDomestic ServicesDrainage effluents746Subsoil drainage747Surface water removal749Road drainage752Rainwater installations754Drainage systems758Drainage---pipe sizes and gradients766Water supply767Cold water installations769Hot water installations771Flow controls774Cisterns and cylinders7...

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    PREFACE TO EIGHTH EDITIONThis edition retains the predominantly illustrative format of earlier editions,presenting the principles of building construction with comprehensive guidanceto procedures with numerous examples of formulated and empirical design.Summary notes are supplemented with referen...

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    1 GENERALBUILT ENVIRONMENTTHE STRUCTUREPRIMARY AND SECONDARY ELEMENTSCONSTRUCTION ACTIVITIESCONSTRUCTION DOCUMENTSCONSTRUCTION DRAWINGSBUILDING SURVEYHIPs/EPCsMATERIAL WEIGHTS AND DENSITIESIMPOSED FLOOR LOADSPLANNING APPLICATIONMODULAR COORDINATIONCONSTRUCTION REGULATIONSCDM REGULATIONSSAFETY SIG...

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    Environment = surroundings which can be natural, man-made or acombination of these.Built Environment = created by man with or without the aid of thenatural environment.2Built Environment

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    Environmental Considerations1. Planning requirements.2. Building Regulations.3. Land restrictions by vendoror lessor.4. Availability of services.5. Local amenities includingtransport.6. Subsoil conditions.7. Levels and topography ofland.8. Adjoining buildings or land.9. Use of building.10. Daylig...

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    Physical considerations1. Natural contours of land.2. Natural vegetation and trees.3. Size of land and/or proposed building.4. Shape of land and/or proposed building.5. Approach and access roads and footpaths.6. Services available.7. Natural waterways, lakes and ponds.8. Restrictions such as righ...

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    5The Structure---Basic Types

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    6The Structure---Basic Types

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    7The Structure---Basic Forms

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    8The Structure---Basic Forms

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    Shell Roofs ~ these are formed by a structural curved skincovering a given plan shape and area.9The Structure---Basic Forms

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    10The Structure---Basic Forms

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    Substructure~canbedefinedasallstructurebelowthesuperstructure which in general terms is considered to include allstructure below ground level but including the ground floor bed.11Substructure

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    Superstructure~canbedefinedasallstructureabovesubstructure both internally and externally.Primary Elements ~ basically components of the building carcassabove the substructure excluding secondary elements, finishes,services and fittings.12Superstructure and Primary Elements

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    SecondaryElements~completionofthestructureincludingcompletion around and within openings in primary elements.13Secondary Elements

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    Finish ~ the final surface which can be self finished as with atrowelled concrete surface or an applied finish such as floor tiles.14Finishes

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    Domestic Structures:~Domestic Structures:~15Structure---Component Parts and Functions

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    Framed Structures:~Framed Structures:~16Structure---Component Parts and Functions

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    External Envelope ~ consists of the materials and componentswhich form the external shell or enclosure of a building. These maybe load bearing or non-load bearing according to the structuralform of the building.17External Envelope---Functions

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    Dwelling houses ~Flats ~Note:Floorswithinamaisonettearenotrequiredtobe``compartment''.For non-residential buildings, compartment size is limited by floorarea depending on the building function (purpose group) and height.Compartment ~ a building or part of a building with walls andfloors construct...

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    A Building or Construction Site can be considered as a temporaryfactory employing the necessary resources to successfully fulfil acontract.Money:~Money:~19Construction Activities---The Site

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    20ConstructionActivities---TheDocuments

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    Location Drawings ~SitePlans†usedtolocatesite,buildings,definesitelevels,indicateservices to buildings, identify parts ofsitesuchasroads,footpathsandboundariesandtogivesettingoutdimensions for the site and buildings asa whole. Suitable scale not less than1 : 2500Floor Plans † used to identify...

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    Sketch ~ this can be defined as a draft or rough outline of an idea,it can be a means of depicting a three-dimensional form in atwo-dimensional guise. Sketches can be produced free-hand or usingrules and set squares to give basic guide lines.All sketches should be clear, show all the necessary de...

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    23CommunicatingInformation---OrthographicProjections

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    Isometric Projections ~ a pictorial projection of a solid object ona plane surface drawn so that all vertical lines remain vertical andof true scale length, all horizontal lines are drawn at an angle of30° and are of true scale length therefore scale measurements canbe taken on the vertical and ...

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    25CommunicatingInformation---PerspectiveProjections

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    26CommunicatingInformation---FloorPlansandElevations

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    1 :27Communicating Information---Block and Site Plans

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    Construction Defects † correct application of materials producedto the recommendations of British, European and InternationalStandardsauthorities,inaccordancewithlocalbuildingregulations, by-laws and the rules of building guarantee companies,i.e. National House Building Council (NHBC) and MD In...

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    EstablishedProcedure†theinterestedpurchaserengagesabuilding surveyor.UK Government Requirements † the seller to provide a property/home information pack (HIP) which can include `A survey report onthe condition of the property, including requirements for urgent orsignificant repairs . . .'.Sur...

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    Estate and garden:* Location and establishment of boundaries* Fences, gates and hedges † material, condition and suitability* Trees † type and height, proximity to building* Pathways and drives † material and condition* Outbuildings † garages, sheds, greenhouses, barns, etc.* Proximity of...

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    Roof space:* Access to all parts, construction type † traditional or trussed* Evidence of moisture due to condensation † ventilation ateaves, ridge, etc.* Evidence of water penetration † chimney flashings, abutmentsand valleys* Insulation † type and quantity* Party wall in semi-detached a...

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    Home Information Packs ~ otherwise known as HIPS or ``seller's packs''.A HIP is provided as supplementary data to the estate agent's salesparticulars by home sellers when marketing a house. The packs placeemphasis on an energy use assessment and contain some contractpreliminaries such as evidence...

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    A method statement precedes preparation of the project programme and contains the detail necessary forconstruction of each element of a building. It is prepared from information contained in the contractdocuments † see page 20. It also functions as a brief for site staff and operatives in seque...

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    34CommunicatingInformation---BarChartProgramme

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    MaterialWeight (kg/m2)BRICKS, BLOCKS and PAVING †Clay brickwork † 102.5 mmlow density205medium density221high density238Calcium silicate brickwork † 102.5 mm205Concrete blockwork, aerated78.. .. .. .. .. .. .. .. lightweight aggregate129Concrete flagstones (50 mm)115Glass blocks (100 mm thi...

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    Densities -Ref. BS 648: Schedule of Weights of Building Materials.MaterialApprox. Density (kg/m3)Cement1440Concrete (aerated)640.. .. .. .. .. .. (broken brick)2000.. .. .. .. .. .. (natural aggregates)2300.. .. .. .. .. .. (no-fines)1760.. .. .. .. .. .. (reinforced)2400Metals -Aluminium2770Copp...

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    Structural design of floors will be satisfied for most situations byusing the minimum figures given for uniformly distributed loading(UDL). These figures provide for static loading and for the dynamicsof occupancy. The minimum figures given for concentrated or pointloading can be used where these...

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    Drawings~thesearetheprincipalmeansofcommunicationbetween the designer, the builder and other parties to a contract.Drawings should therefore be clear, accurate, contain all thenecessary information and be capable of being easily read.Design practices have their own established symbols and notatio...

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    Hatchings ~ the main objective is to differentiate between thematerials being used thus enabling rapid recognition and location.Whichever hatchings are chosen they must be used consistentlythroughout the whole set of drawings. In large areas it is notalways necessary to hatch the whole area.Symbo...

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    ,40Drawings---Hatchings, Symbols and Notations

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    41Drawings---Using Hatchings and Symbols

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    Principal legislation: ~The Town & Country Planning Act 1990 † Effects control overvolume of development, appearance and layout of buildings. ThePublic Health Acts 1936 to 1961 † Limits development with regard toemission of noise, pollution and public nuisance. The Highways Act1980 † De...

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    43Planning Application---Householder

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    44Planning Application---New Build (1)

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    45Planning Application---New Build (2)

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    TOWN AND COUNTRY PLANNING ACTTOWN AND COUNTRY PLANNING (General Development Procedure) ORDERCertificates under Article 7 of the OrderCERTIFICATE AFor Freehold Owner (or his/her Agent) I hereby certify that:- 1.No person other than the applicant was an owner of any part of the land to which the ap...

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    Modular Coordination ~ a module can be defined as a basicdimension which could for example form the basis of a planning gridin terms of multiples and submultiples of the standard module.Typical Modular Coordinated Planning Grid ~Let M = the standard moduleStructural Grid ~ used to locate structur...

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    Dimensional Coordination ~ the practical aims of this concept are to:-1. Size components so as to avoid the wasteful process ofcutting and fitting on site.2. Obtain maximum economy in the production of components.3. Reduce the need for the manufacture of special sizes.4. Increase the effective ch...

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    Construction Regulations ~ these are Statutory Instruments madeunder the Factories Acts of 1937 and 1961 and come under theumbrella of the Health and Safety at Work etc., Act 1974. They setout the minimum legal requirements for construction works andrelate primarily to the health, safety and welf...

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    Objective†Tocreateanall-partyintegratedandplannedapproach to health and safety throughout the duration of aconstruction project.Administering Body † The Health and Safety Executive (HSE).Scope † The CDM Regulations are intended to embrace all aspectsof construction, with the exception of ve...

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    Under these regulations, employers are required to provide andmaintain health and safety signs conforming to European Directive92/58 EEC:In addition, employers obligations include the need to provide:Risk Assessment † provide and maintain safety signs where there isarisktohealthandsafety,e.g.ob...

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    Ref. BS 5499-1: Graphical symbols and signs. Safety signs, includingfire safety signs. Specification for geometric shapes, colours andlayout.52Health and Safety---Signs and Symbols (2)

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    The Building Regulations ~ this is a Statutory Instrument whichsets out the minimum performance standards for the design andconstruction of buildings and where applicable to the extension ofbuildings. The regulations are supported by other documents whichgenerallygiveguidanceonhowtoachievetherequ...

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    Approved Documents ~ these publications support the BuildingRegulations. They are prepared by the Department for Communitiesand Local Government approved by the Secretary of State and issuedby The Stationery Office. The Approved Documents (ADs) have beencompiled to give practical guidance to comp...

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    Example in the Use of Approved DocumentsProblem:- the sizing of suspended upper floor joists to be spacedat 400 mm centres with a clear span of 3„600 m for usein a two storey domestic dwelling.Building Regulation A1:- states that the building shall be constructedso that the combined dead, impos...

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    Building Control ~ unless the applicant has opted for control by aprivateapprovedinspectorunderTheBuilding(ApprovedInspectors etc.) Regulations 2000 the control of building works inthe context of the Building Regulations is vested in the LocalAuthority. There are two systems of control namely the...

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    Building Regulations Approval ~ required if ``Building Work'' asdefined in Regulation 3 of the Building Regulations is proposed.This includes:• Construction or extension of a building.• Alterations to an existing building that would bring into effectany of the complying regulations.• Instal...

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    Local Authority Building Control ~ as described in the previoustwo pages. A public service administered by borough and unitarycouncils through their building control departments.Approved Inspectors ~ a private sector building control alternativeas outlined on the preceding page. Approved inspecto...

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    Deposit of Plans or Full Plans Application ~• Application form describing the proposed work.• Location plan, scale not less than 1 : 2500.• Block plan, scale not less than 1 : 1250 showing north point,lines of drains (existing and proposed) and size and species oftrees within 30 m.• Plans...

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    60BuildingRegulationsExemptions

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    61Building Regulations---Full Plans

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    Published ~ 2006 by the Department for Communities and LocalGovernment (DCLG) in response to the damaging effects of climatechange. The code promotes awareness and need for new energyconservation initiatives in the design of new dwellings.Objective ~ to significantly reduce the 27% of UK CO2 emis...

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    British Standards ~ these are publications issued by the BritishStandards Institution which give recommended minimum standardsformaterials,components,designandconstructionpractices.These recommendations are not legally enforceable but some ofthe Building Regulations refer directly to specific Bri...

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    European Standards † since joining the European Union (EU), tradeand tariff barriers have been lifted. This has opened up the marketfor manufacturers of construction-related products, from all EUand European Economic Area (EEA) member states. Before 2004,the EU was composed of 15 countries: Aus...

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    Formanufacturers'productstobecompatibleanduniformlyacceptable in the European market, there exists a process forharmonising technical specifications. These specifications are knownas harmonised European product standards (hENs), produced andadministered by the Comite' Europe'en de Normalisation (...

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    Building Research Establishment ~ The BRE was founded as a UKGovernment agency in 1921 and was known until the early 1970s asthe Building Research Station.In addition to UK Government funding, some financial support isnow provided by the European Union. Additional funding is derivedfrom a variety...

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    CPI System of Coding ~ the Co-ordinated Project Informationinitiative originated in the 1970s in response to the need toestablishacommonarrangementofdocumentandlanguagecommunication, across the varied trades and professions of theconstruction industry.However, it has only been effective in recent...

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    CI/SfB System ~ this is a coded filing system for the classificationand storing of building information and data. It was created inSweden under the title of Samarbetskommitte..nfo..r Byggnadsfraƒgorand was introduced into this country in 1961 by the RIBA. In 1968the CI (Construction Index) was a...

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    2 SITE WORKSSITE INVESTIGATIONSSOIL INVESTIGATIONSOIL ASSESSMENT AND TESTINGSITE LAYOUT CONSIDERATIONSSITE SECURITYSITE LIGHTING AND ELECTRICAL SUPPLYSITE OFFICE ACCOMMODATIONMATERIALS STORAGEMATERIALS TESTING†BRICKS AND CONCRETEMATERIALS TESTING†SOFTWOOD CHARACTERISTICSTIMBER DECAY AND TREAT...

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    Site Analysis † prior to purchasing a building site it is essential toconductathoroughsurveytoascertainwhetherthesitecharacteristicssuitthedevelopmentconcept.Thefollowingguidance forms a basic checklist:* Refer to Ordnance Survey maps to determine adjacent features,location, roads, facilities, ...

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    Site Investigation For New Works ~ the basic objective of this formof site investigation is to collect systematically and record all thenecessary data which will be needed or will help in the design andconstruction processes of the proposed work. The collected datashould be presented in the form ...

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    Procedures ~1 . Desk study2. Field study or walk-over survey3. Laboratory analysis (see pages 81†82 and 85†87)Desk Study ~ collection of known data, to include:• OrdnanceSurveymaps†historicalandmodern,notegridreference.• Geological maps † subsoil types, radon risk.• Site history †...

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    Purpose ~ primarily to obtain subsoil samples for identification,classification and ascertaining the subsoil's characteristics andproperties. Trial pits and augered holes may also be used toestablish the presence of any geological faults and the upper orlower limits of the water table.General use...

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    Site Investigation ~ this is an all embracing term covering everyaspect of the site under investigation.Soil Investigation ~ specifically related to the subsoil beneath thesite under investigation and could be part of or separate from thesite investigation.Purpose of Soil Investigation ~1 . Deter...

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    Depth of Soil Investigation ~ before determining the actual methodof obtaining the required subsoil samples the depth to which thesoil investigation should be carried out must be established. This isusually based on the following factors †1 . Proposed foundation type.2. Pressure bulb of propose...

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    76Soil Investigation

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    Soil Investigation Methods ~ method chosen will depend on severalfactors †1 . Size of contract.2. Type of proposed foundation.3. Type of sample required.4. Type of subsoils which may be encountered.Asageneralguidethe mostsuitablemethods intermsofinvestigation depth are †1 . Foundations up to3...

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    Boring Methods to Obtain Disturbed Soil Samples ~1 . Hand or Mechanical Auger † suitable for depths up to 3Á 000using a 150 or 200 mm diameter flight auger.2. Mechanical Auger † suitable for depths over 3Á 000 using aflight or Cheshire auger † a liner or casing is required formost granula...

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    Wash Boring ~ this is a method of removing loosened soil from abore hole using a strong jet of water or bentonite which is acontrolled mixture of fullers earth and water. The jetting tube isworked up and down inside the bore hole, the jetting liquiddisintegrates the subsoil which is carried in su...

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    Bore Hole Data ~ the information obtained from trial pits or bore holescan be recorded on a pro forma sheet or on a drawing showing theposition and data from each trial pit or bore hole thus:-Bore holes can be taken on a 15„ 000 to 20„ 000 grid covering thewhole site or in isolated positions ...

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    Soil Assessment ~ prior to designing the foundations for a buildingor structure the properties of the subsoil(s) must be assessed.These processes can also be carried out to confirm the suitabilityoftheproposedfoundations.Soilassessmentcanincludeclassification,grading,teststoestablishshearstrength...

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    Triangular Chart ~ this provides a general classification of soilscomposed predominantly from clay, sand and silt. Each side of thetriangle represents a percentage of material component. Followinglaboratory analysis, a sample's properties can be graphicallyplotted on the chart and classed accordi...

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    Site Soil Tests ~ these tests are designed to evaluate the densityor shear strength of soils and are very valuable since they do notdisturb the soil under test. Three such tests are the standardpenetration test, the vane test and the unconfined compressiontest all of which are fully described in ...

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    Soil Assessment and TestingVane Test ~ this test measures the shear strength of soft cohesive soils. The steel vane is pushed into the soft clay soil and rotated by hand at a constant rate. The amount of torque necessary for rotation is measured and the soil shear strength calculated as shown bel...

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    Unconfined Compression Test ~ this test can be used to establishthe shear strength of a non-fissured cohesive soil sample usingportable apparatus either on site or in a laboratory. The 75 mmlong¾ 38 mm diameter soil sample is placed in the apparatus andloaded in compression until failure occurs ...

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    Laboratory Testing ~ tests for identifying and classifying soils withregard to moisture content, liquid limit, plastic limit, particle sizedistribution and bulk density are given in BS 1377.Bulk Density ~ this is the mass per unit volume which includes massof air or water in the voids and is esse...

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    Shear Strength ~ this can be defined as the resistance offered by asoil to the sliding of one particle over another. A simple method ofestablishing this property is the Shear Box Test in which theapparatus consists of two bottomless boxes which are filled withthe soil sample to be tested. A horiz...

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    General Considerations ~ before any specific considerations anddecisions can be made regarding site layout a general appreciationshould be obtained by conducting a thorough site investigation atthepre-tenderstageandexaminingindetailthedrawings,specification and Bill of Quantities to formulate pro...

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    Storage Considerations ~ amount and types of material to bestored, security and weather protection requirements, allocation ofadequate areas for storing materials and allocating adequateworking space around storage areas as required, siting of storageareas to reduce double handling to a minimum w...

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    90Site Layout Considerations

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    Site Security ~ the primary objectives of site security are †1 . Security against theft.2. Security from vandals.3. Protection from innocent trespassers.The need for and type of security required will vary from site tosite according to the neighbourhood, local vandalism record andthe value of g...

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    Hoardings ~ under the Highways Act 1980 a close boarded fencehoarding must be erected prior to the commencement of buildingoperations if such operations are adjacent to a public footpath orhighway. The hoarding needs to be adequately constructed toprovide protection for the public, resist impact ...

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    93Hoardings

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    Site Lighting ~ this can be used effectively to enable work to continueduring periods of inadequate daylight. It can also be used as a deterrentto would-be trespassers. Site lighting can be employed externally toilluminate the storage and circulation areas and internally for generalmovement and f...

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    Typical Site Lighting Arrangement:-Typical minimum heights for dispersive lamps:Fluorescent 40 to 125 W † 2„ 500 m; Tungsten filament 300 W † 3„ 000 m95Site Lighting

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    Walkway and Local Lighting ~ to illuminate the general circulationroutes bulkhead and/or festoon lighting could be used either on astandard mains voltage of 230 V or on a reduced voltage of 110 V.For local lighting at the place of work hand lamps with trailingleads or lamp fittings on stands can ...

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    Electrical Supply to Building Sites ~ a supply of electricity is usuallyrequired at an early stage in the contract to provide light and power tothe units of accommodation. As the work progresses power could alsobe required for site lighting, hand held power tools and large items ofplant. The supp...

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    OfficeAccommodation~thearrangementsforofficeaccommodation to be provided on site is a matter of choice foreach individual contractor. Generally separate offices would beprovided for site agent, clerk of works, administrative staff, sitesurveyors and sales staff.The minimum requirements of such ac...

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    The requirements for health and wellbeing of persons on constructionsites are enforced by the Health and Safety Executive, through theHealth and Safety at Work etc. Act 1974 and the Construction(Health, Safety and Welfare) Regulations 1996. The following minimumrequirements apply and the numbers ...

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    Site Storage ~ materials stored on site prior to being used or fixedmay require protection for security reasons or against the adverseeffects which can be caused by exposure to the elements.Small and Valuable Items ~ these should be kept in a secure andlockable store. Similar items should be stor...

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    Storage of Materials ~ this can be defined as the provision ofadequate space, protection and control for building materials andcomponents held on site during the construction process. Theactualrequirementsforspecificitemsshouldbefamiliartostudents who have completed studies in construction techno...

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    Site Storage Space ~ the location and size(s) of space to beallocatedforanyparticularmaterialshouldbeplannedbycalculating the area(s) required and by taking into account all therelevant factors before selecting the most appropriate position onsite in terms of handling, storage and convenience. Fa...

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    Site Allocation for Materials Storage ~ the area and type ofstorage required can be determined as shown on pages 100 to 102,but the allocation of an actual position on site will depend on:-1 . Space available after areas for units of accommodation havebeen allocated.2. Access facilities on site f...

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    Bricks ~ may be supplied loose or strapped in unit loads and storedon timber pallets104Materials Storage

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    Drainage Pipes ~ supplied loose or strapped together on timberpalletsGullies etc., should be stored upside down and supported to remainlevelCement, Sand and Aggregates ~ for supply and storage details seepages 285 & 289.105Materials Storage

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    Site Tests ~ the majority of materials and components arriving onsitewillconformtotheminimumrecommendationsoftheappropriate British Standard and therefore the only tests whichneed be applied are those of checking quantity received againstamount stated on the delivery note, ensuring quality is as ...

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    Site Test ~ apart from the test outlined on page 83 site tests onmaterials which are to be combined to form another material suchas concrete can also be tested to establish certain propertieswhich if not known could affect the consistency and/or quality ofthe final material.Typical Example ~ Test...

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    Silt Test for Sand ~ the object of this test is to ascertain thecleanliness of sand by establishing the percentage of silt present ina natural sand since too much silt will weaken the concreteObtaining Samples for Laboratory Testing ~ these tests may berequired for checking aggregate grading by m...

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    Concrete requires monitoring by means of tests to ensure thatsubsequent mixes are of the same consistency and this can becarried out on site by means of the slump test and in a laboratoryby crushing test cubes to check that the cured concrete hasobtained the required designed strength.The slump c...

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    Non destructive testing of concrete. Also known as in-place orin-situ tests.Changes over time and in different exposures can be monitored.References: BS 6089: Guide to assessment of concrete strength inexisting structures;BS 1881: Testing concrete.BS EN 13791: Assessment of in-situ compressive st...

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    PenetrationorWindsorprobetest~therearevariousinterpretations of this test. It is a measure of the penetration of asteel alloy rod, fired by a predetermined amount of energy intoconcrete.Inprinciple,thedepthofpenetrationisinverselyproportionaltotheconcretecompressivestrength.Severalrecordings are ...

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    Vibration test ~ a number of electronic tests have been devised,which include measurement of ultrasonic pulse velocity throughconcrete.Thisappliestheprincipleofrecordingapulseatpredetermined frequencies over a given distance. The apparatusincludes transducers in contact with the concrete, pulse g...

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    The quality of softwood timber for structural use depends very muchon the environment in which it is grown and the species selected. Timbercan be visually strength graded, but this is unlikely to occur at theconstruction site except for a general examination for obvioushandling defects and damage...

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    Grading ~ either visually or by computerised machine. Individualrectangular timber sections are assessed against permissible defectlimitations and grade marked accordingly.UK grading standard ~ BS 4978.European grading standard ~ BS EN 14081 (4 parts).The two principal grades apart from rejects a...

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    BS EN 338: Structural softwood classifications and typical strength properties ~BS EN338strengthclassBendingparallelto grain(N/mm2)Tensionparallelto grain(N/mm2)Compres-sionparallelto grain(N/mm2)Compres-sion per-pendicularto grain(N/mm2)Shearparallelto grain(N/mm2)Modulusof Mean(N/mm2)Elasticity...

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    Visual strength grading ~ ``process by which a piece of timber canbe sorted, by means of visual inspection, into a grade to whichcharacteristic values of strength, stiffness and density may beallocated''. Definition from BS EN 14081-1.Characteristics:Knots ~ branch growth from or through the main...

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    Fissures and resin pockets ~ defects in growth. Fissures, alsoknown as shakes, are usually caused by separation of annualgrowthrings.Fissuresandresinpocketsmustbelimitedinstructural timber as they reduce resistance to shear and bendingparallel to the grain.A + B = fissure sizeC = fiss...

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    Wane or waney edge ~ occurs on timber cut close to the outersurface of the log producing incomplete corners. Measurement isparallel to the edge or face of section and it is expressed as afraction of the surface dimension.Growth rate ~ measurement is applied to the annual growth ringseparation ave...

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    Characteristics and tolerances of GS and SS graded timber ~CriteriaGSSSKAR:MKAR 1/2MKAR 1/2No marginconditionTKAR 1/2TKAR 1/3Or:KAR:MKAR > 1/2MKAR > 1/2MarginconditionTKAR 1/3TKAR 1/5Fissures andresin pockets:Defects 1 /2 timber thick-nessDefects 1 /2 timberthicknessNot throughthickness<...

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    Structuralsoftwoodcrosssectionalsizehasestablishedterminology such as, sawn, basic and unwrought as produced byconversion of the log into commercial dimensions, e.g. 100¾ 50 mmand 225¾ 75 mm (400¾ 200and 900¾ 300respectively, as the nearestimperial sizes).Timber is converted in imperial and m...

  • Page 134

    Damp conditions can be the source of many different types ofwood-decaying fungi. The principal agencies of decay are †* Dry rot (Serpula lacrymans or merulius lacrymans), and* Wet rot (Coniophora cerabella)Dry rot † this is the most difficult to control as its root systemcan penetrate damp an...

  • Page 135

    Causes †* Defective construction, e.g. broken roof tiles; no damp-proofcourse.* Installation of wet timber during construction, e.g. framingsealed behind plasterboard linings; wet joists under floordecking.* Lack of ventilation, e.g. blocked air bricks to suspended timberground floor; condensat...

  • Page 136

    Trees ~ these are part of our national heritage and are also the sourceof timber † to maintain this source a control over tree felling has beenestablished under the Forestry Act 1967 which places the controlresponsibility on the Forestry Commission. Local planning authoritiesalso have powers un...

  • Page 137

    Services which may be encountered on construction sites and theauthority responsible are:-Water † Local Water CompanyElectricity † transmission ~ RWE npower, BNFL and E-on.distribution ~ Area Electricity Companies in Englandand Wales. Scottish Power and ScottishHydro-Electric, EDF Energy.Gas ...

  • Page 138

    Setting Out the Building Outline ~ this task is usually undertakenonce the site has been cleared of any debris or obstructions and anyreducedlevelexcavationworkisfinished.Itisusuallytheresponsibility of the contractor to set out the building(s) using theinformation provided by the designer or arc...

  • Page 139

    Setting Out Trenches ~ the objective of this task is twofold.Firstly it must establish the excavation size, shape and directionand secondly it must establish the width and position of the walls.The outline of building will have been set out and using this outlineprofile boards can be set up to co...

  • Page 140

    Setting Out a Framed Building ~ framed buildings are usuallyrelated to a grid, the intersections of the grid lines being thecentre point of an isolated or pad foundation. The grid is usuallyset out from a base line which does not always form part of thegrid. Setting out dimensions for locating th...

  • Page 141

    Setting Out Reduced Level Excavations ~ the overall outline ofthe reduced level area can be set out using a theodolite, rangingrods, tape and pegs working from a base line. To control the depthof excavation, sight rails are set up at a convenient height and atpositions which will enable a travell...

  • Page 142

    Levelling ~ the process of establishing height dimensions, relativeto a fixed point or datum. Datum is mean sea level, which variesbetween different countries. For UK purposes this is established atNewlyn in Cornwall, from tide data recorded between May 1915 andApril 1921. Relative levels defined...

  • Page 143

    130Setting Out---Levelling

  • Page 144

    Theodolite † a tripod mounted instrument designed to measureangles in the horizontal or vertical plane.The theodolite in principleMeasurement † a telescope provides for focal location betweeninstrument and subject. Position of the scope is defined by an index ofangles. The scale and presentat...

  • Page 145

    Road Construction ~ within the context of building operationsroadworks usually consist of the construction of small estateroads, access roads and driveways together with temporary roadslaid to define site circulation routes and/or provide a suitablesurface for plant movements. The construction of...

  • Page 146

    Earthworks ~ this will involve the removal of topsoil together withany vegetation, scraping and grading the required area down toformationlevelplustheformationofanycuttingsorembankments. Suitable plant for these operations would be tractorshovels fitted with a 4 in 1 bucket (page 174): graders (p...

  • Page 147

    Rigid Pavings ~ these consist of a reinforced or unreinforced in-situconcrete slab laid over a base course of crushed stone or similarmaterial which has been blinded to receive a polythene sheet slipmembrane. The primary objective of this membrane is to preventgrout loss from the in-situ slab.134...

  • Page 148

    Joints in Rigid Pavings ~ longitudinal and transverse joints arerequired in rigid pavings to:-1 . Limit size of slab.2. Limit stresses due to subgrade restraint.3. Provide for expansion and contraction movements.The main joints used are classified as expansion, contraction orlongitudinal, the lat...

  • Page 149

    136Roads---Footpaths

  • Page 150

    137Roads---Kerbs, Pavings and Edgings

  • Page 151

    Concrete paving flags † BS dimensions:Note: All dimensions in millimetres.Tactile flags † manufactured with a blistered (shown) or ribbedsurface. Used in walkways to provide warning of hazards or toenable recognition of locations for people whose visibility isimpaired. See also, Department of...

  • Page 152

    Landscaping ~ in the context of building works this would involvereinstatement of the site as a preparation to the landscaping inthe form of lawns, paths, pavings, flower and shrub beds and treeplanting. The actual planning, lawn laying and planting activitiesare normally undertaken by a landscap...

  • Page 153

    Scaffolds ~ these are temporary working platforms erected aroundthe perimeter of a building or structure to provide a safe workingplace ataconvenient height. They are usually required when theworking height or level is 1„ 500 or more above the ground level.All scaffolds must comply with the min...

  • Page 154

    Putlog Scaffolds ~ these are scaffolds which have an outer row ofstandards joined together by ledgers which in turn support thetransverse putlogs which are built into the bed joints or perpendsas the work proceeds, they are therefore only suitable for newwork in bricks or blocks.141Tubular Scaffo...

  • Page 155

    Independent Scaffolds ~ these are scaffolds which have two rowsof standards each row joined together with ledgers which in turnsupport the transverse transoms. The scaffold is erected clear ofthe existing or proposed building but is tied to the building orstructure at suitable intervals † see p...

  • Page 156

    Working Platforms ~ these are close boarded or plated level surfacesat a height at which work is being carried out and they must provide asafe working place of sufficient strength to support the imposed loadsof operatives and/or materials. All working platforms above theground level must be fitte...

  • Page 157

    Tying-in ~ all putlog and independent scaffolds should be tiedsecurely to the building or structure at alternate lift heightsvertically and at not more than 6„ 000 centres horizontally.Putlogs should not be classified as ties.Suitabletying-inmethodsincludeconnectingtotubesfittedbetween sides of...

  • Page 158

    Mobile Scaffolds ~ otherwise known as mobile tower scaffolds. They canbe assembled from pre-formed framing components or from standardscaffold tube and fittings. Used mainly for property maintenance. Mustnot be moved whilst occupied by persons or equipment.145Tubular Scaffolding

  • Page 159

    Some basic fittings ~Reveal pin Base plate scaffold tube scaffold tube over circular spigot welded to 150 mm square plate circular nut with "podger" recess face plate Wrapover putlog coupler Split joint pin bolt swing over bolt swing over bolt Putlog end putlog tube blade scaffold tube ...

  • Page 160

    Patent Scaffolding ~ these are systems based on an independentscaffold format in which the members are connected together usinganintegrallockingdeviceinsteadofconventionalclipsandcouplers used with traditional tubular scaffolding. They havethe advantages of being easy to assemble and take down us...

  • Page 161

    Scaffolding Systems ~ these are temporary stagings to providesafeaccesstoandegressfromaworkingplatform.Thetraditional putlog and independent scaffolds have been covered onpages140to144inclusive.TheminimumlegalrequirementscontainedintheConstruction(HealthSafetyandWelfare)Regulations 1996 applicabl...

  • Page 162

    Suspended Scaffolds ~ these consist of a working platform in theform of a cradle which is suspended from cantilever beams oroutriggers from the roof of a tall building to give access to thefac¸ade for carrying out light maintenance work and cleaningactivities. The cradles can have manual or powe...

  • Page 163

    Cantilever Scaffolds ~ these are a form of independent tiedscaffolderectedoncantileverbeamsandusedwhereitisimpracticable, undesirable or uneconomic to use a traditionalscaffold raised from ground level. The assembly of a cantileverscaffold requires special skills and should therefore always becar...

  • Page 164

    Truss-out Scaffold ~ this is a form of independent tied scaffoldused where it is impracticable, undesirable or uneconomic to build ascaffold from ground level. The supporting scaffold structure isknown as the truss-out. The assembly of this form of scaffoldrequires special skills and should there...

  • Page 165

    Gantries ~ these are elevated platforms used when the buildingbeing maintained or under construction is adjacent to a publicfootpath. A gantry over a footpath can be used for storage ofmaterials, housing units of accommodation and supporting anindependent scaffold. Local authority permission will...

  • Page 166

    Shoring ~ this is a form of temporary support which can be givento existing buildings with the primary function of providing thenecessary precautions to avoid damage to any person fromcollapse of structure as required by the Construction (Health,Safety and Welfare) Regulations 1996.Shoring System...

  • Page 167

    Dead Shores ~ these shores should be placed at approximately2„ 000 c/c and positioned under the piers between the windows,any windows in the vicinity of the shores being strutted to preventdistortion of the openings. A survey should be carried out toestablish the location of any underground ser...

  • Page 168

    Raking Shoring ~ these are placed at 3„ 000 to 4„ 500 c/c and canbe of single, double, triple or multiple raker format. Suitablematerialsaretimber,structuralsteelandframedtubularscaffolding.155Shoring

  • Page 169

    Flying Shores ~ these are placed at 3„000 to 4„500 c/c and can be of a single or double format. They aredesigned, detailed and constructed to the same basic principles as that shown for raking shores on page 155.Unsymmetrical arrangements are possible providing the basic principles for flying...

  • Page 170

    157Shoring

  • Page 171

    Unsymmetrical Flying Shores ~ arrangements of flying shores forunsymmetrical situations can be devised if the basic principles forsymmetrical shores is applied (see page 156). In some cases thearrangement will consist of a combination of both raking and flyingshore principles.158Shoring

  • Page 172

    Temporary Support Determination ~ the basic sizing of mosttemporary supports follows the principles of elementary structuraldesign. Readers with this basic knowledge should be able tocalculate such support members which are required, particularlythose used in the context of the maintenance and ad...

  • Page 173

    Design calculations reference previous page.Timber strength class C22, See page 115 for data.BM =WL4=39300¾ 30004= 29475000 NmmMR = stress¾ section modulus = fZ = fbd26assume b = 300 mm and f = 6.8 N/mm2then 29475000 =6: 8¾ 300¾ d26d=ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi...

  • Page 174

    Stability check using the example from previous page ~Timber of strength classification C22 (see page 115):Modulus of elasticity, 6500 N/mm2 minimum.Grade stress in compression parallel to the grain, 7.5 N/mm2.Grade stress ratio = 6500… 7.5 = 867The grade stress and slenderness ratios are used ...

  • Page 175

    Town and Country Planning Act ~ demolition is generally not regardedas development, but planning permission will be required if the site is tohave a change of use. Attitudes to demolition can vary between localplanning authorities and consultation should be sought.Planning (Listed Buildings and C...

  • Page 176

    163Demolition -- Notice

  • Page 177

    Demolition ~ skilled and potentially dangerous work that shouldonly be undertaken by experienced contractors.Types of demolition ~ partial or complete removal. Partial is lessdynamic than complete removal, requiring temporary support tothe remaining structure. This may involve window strutting, f...

  • Page 178

    Generally ~ the reverse order of construction to gradually reducethe height. Where space in not confined, overturning or explosivesmay be considered.Piecemeal ~ useof handheldequipmentsuchas pneumaticbreakers, oxy-acetylene cutters, picks and hammers. Care should betaken when salvaging materials ...

  • Page 179

    Concept ~ to reduce waste by designing for deconstruction.Linear (wasteful, non-sustainable) process ~Production andcomponentmanufactureMaterialresourceextractionDisposal/landfillof residualmaterialBuilding assemblyand occupancyover design lifeDecommissionanddemolitionLimitedunderEU LandfillDirec...

  • Page 180

    3 BUILDERS PLANTGENERAL CONSIDERATIONSBULLDOZERSSCRAPERSGRADERSTRACTOR SHOVELSEXCAVATORSTRANSPORT VEHICLESHOISTSRUBBLE CHUTES AND SKIPSCRANESCONCRETING PLANT167

  • Page 181

    General Considerations ~ items of builders plant ranging from smallhand held power tools to larger pieces of plant such as mechanicalexcavators and tower cranes can be considered for use for one ormore of the following reasons:-1 . Increased production.2. Reduction in overall construction costs.3...

  • Page 182

    Plant Costing ~ with the exception of small pieces of plant, whichare usually purchased, items of plant can be bought or hired orwhere there are a number of similar items a combination of buyingand hiring could be considered. The choice will be governed byeconomic factors and the possibility of u...

  • Page 183

    Output and Cycle Times ~ all items of plant have optimum outputand cycle times which can be used as a basis for estimatinganticipated productivity taking into account the task involved,task efficiency of the machine, operator's efficiency and in the caseof excavators the type of soil. Data for th...

  • Page 184

    Bulldozers ~ these machines consist of a track or wheel mountedpower unit with a mould blade at the front which is controlled byhydraulic rams. Many bulldozers have the capacity to adjust themould blade to form an angledozer and the capacity to tilt themould blade about a central swivel point. So...

  • Page 185

    Scrapers ~ these machines consist of a scraper bowl which islowered to cut and collect soil where site stripping and levellingoperations are required involving large volume of earth. When thescraper bowl is full the apron at the cutting edge is closed toretain the earth and the bowl is raised for...

  • Page 186

    Graders ~ these machines are similar in concept to bulldozers inthat they have a long slender adjustable mould blade, which isusually slung under the centre of the machine. A grader's mainfunction is to finish or grade the upper surface of a large areausually as a follow up operation to scraping ...

  • Page 187

    Tractor Shovels ~ these machines are sometimes called loaders orloader shovels and primary function is to scoop up loose materialsin the front mounted bucket, elevate the bucket and manoeuvreinto a position to deposit the loose material into an attendanttransport vehicle. Tractor shovels are driv...

  • Page 188

    Excavating Machines ~ these are one of the major items ofbuilders plant and are used primarily to excavate and load mosttypes of soil. Excavating machines come in a wide variety ofdesigns and sizes but all of them can be placed within one of threecategories:-1. Universal Excavators † this categ...

  • Page 189

    Face Shovels ~ the primary function of this piece of plant is toexcavate above its own track or wheel level. They are available asa universal power unit based machine or as a hydraulic purposedesigned unit. These machines can usually excavate any type ofsoil except rock which needs to be loosened...

  • Page 190

    Backacters ~ these machines are suitable for trench, foundationand basement excavations and are available as a universal powerunit base machine or as a purpose designed hydraulic unit. Theycan be used with or without attendant haulage vehicles since thespoil can be placed alongside the excavation...

  • Page 191

    Draglines ~ these machines are based on the universal power unitwith basic crane rigging to which is attached a drag bucket. Themachine is primarily designed for bulk excavation in loose soils upto 3„000 below its own track level by swinging the bucket out tothe excavation position and hauling ...

  • Page 192

    Multi-purpose Excavators ~ these machines are usually based onthe agricultural tractor with 2 or 4 wheel drive and are intendedmainly for use in conjunction with small excavation works such asthoseencounteredbythesmalltomediumsizedbuildingcontractor. Most multi-purpose excavators are fitted with ...

  • Page 193

    Transport Vehicles ~ these can be defined as vehicles whoseprimary function is to convey passengers and/or materials betweenand around building sites. The types available range from theconventional saloon car to the large low loader lorries designed totransport other items of builders plant betwe...

  • Page 194

    Dumpers ~ these are used for the horizontal transportation ofmaterials on and off construction sites generally by means of anintegral tipping skip. Highway dumpers are of a similar but largerdesign and can be used to carry materials such as excavated spoilalong the roads. A wide range of dumpers ...

  • Page 195

    Fork Lift Trucks ~ these are used for the horizontal and limitedvertical transportation of materialspositioned on pallets orbanded together such as brick packs. They are generally suitablefor construction sites where the building height does not exceedthree storeys. Although designed to negotiate...

  • Page 196

    Hoists ~ these are designed for the vertical transportation ofmaterials, passengers or materials and passengers (see page 184).Materials hoists are designed for one specific use (i.e. the verticaltransportation of materials) and under no circumstances shouldthey be used to transport passengers. M...

  • Page 197

    PassengerHoists~thesearedesignedtocarrypassengersalthough most are capable of transporting a combined load ofmaterials and passengers within the lifting capacity of the hoist. Awide selection of hoists are available ranging from a single cagewith rope suspension to twin cages with rack and pinion...

  • Page 198

    Rubble Chutes ~ these apply to contracts involving demolition,repair, maintenance and refurbishment. The simple concept ofconnecting several perforated dustbins is reputed to have beenconceived by an ingenious site operative for the expedient and safeconveyance of materials.In purpose designed fo...

  • Page 199

    Cranes ~ these are lifting devices designed to raise materials bymeans of rope operation and move the load horizontally within thelimitations of any particular machine. The range of cranes availableis very wide and therefore choice must be based on the loads to belifted, height and horizontal dis...

  • Page 200

    Self Propelled Cranes ~ these are mobile cranes mounted on awheeled chassis and have only one operator position from whichthe crane is controlled and the vehicle driven. The road speed ofthis type of crane is generally low, usually not exceeding 30 kmp.h. A variety of self propelled crane formats...

  • Page 201

    Lorry Mounted Cranes ~ these mobile cranes consist of a latticeor telescopic boom mounted on a specially adapted truck or lorry.They have two operating positions: the lorry being driven from aconventional front cab and the crane being controlled from adifferent location. The lifting capacity of t...

  • Page 202

    Lorry Mounted Lattice Jib Cranes ~ these cranes follow the samebasic principles as the lorry mounted telescopic cranes but theyhave a lattice boom and are designed as heavy duty cranes withlifting capacities in excess of 100 tonnes. These cranes will requirea firm level surface from which to oper...

  • Page 203

    Track Mounted Cranes ~ these machines can be a universal powerunit rigged as a crane (see page 178) or a purpose designed trackmounted crane with or without a fly jib attachment. The lattertype are usually more powerful with lifting capacities up to 45tonnes. Track mounted cranes can travel and c...

  • Page 204

    Gantry Cranes ~ these are sometimes called portal cranes andconsist basically of two `A' frames joined together with a crossmember on which transverses the lifting appliance. In small gantrycranes (up to 10 tonnes lifting capacity) the `A' frames are usuallywheel mounted and manually propelled wh...

  • Page 205

    Mast Cranes ~ these are similar in appearance to the familiartower cranes but they have one major difference in that the mastor tower is mounted on the slewing ring and thus rotates whereasa tower crane has the slewing ring at the top of the tower andtherefore only the jib portion rotates. Mast c...

  • Page 206

    Tower Cranes ~ most tower cranes have to be assembled anderected on site prior to use and can be equipped with a horizontalor luffing jib. The wide range of models available often make itdifficult to choose a crane suitable for any particular site but mosttower cranes can be classified into one o...

  • Page 207

    194Cranes

  • Page 208

    195Cranes

  • Page 209

    196Cranes

  • Page 210

    197Cranes

  • Page 211

    Concreting ~ this site activity consists of four basic procedures †1 . Material Supply and Storage † this is the receiving on site ofthe basic materials namely cement, fine aggregate and coarseaggregate and storing them under satisfactory conditions. (seeConcrete Production † Materials on p...

  • Page 212

    Concrete Mixers ~ apart from the very large output mixers mostconcrete mixers in general use have a rotating drum designed toproduce a concrete without segregation of the mix.Concreting Plant ~ the selection of concreting plant can beconsidered under three activity headings †1. Mixing. 2. Trans...

  • Page 213

    Medium Batch Mixers ~ outputs of these mixers range from 200 to750 litres and can be obtained at the lower end of the range as atilting drum mixer or over the complete range as a non-tilting drummixer with either reversing drum or chute discharge. The latterusually having a lower discharge height...

  • Page 214

    Transporting Concrete ~ the usual means of transporting mixedconcrete produced in a small capacity mixer is by wheelbarrow.The run between the mixing and placing positions should be kept toa minimum and as smooth as possible by using planks or similarmaterialstopreventsegregationofthemixwithinthe...

  • Page 215

    Concrete Pumps ~ these are used to transport large volumes ofconcrete in a short time period (up to 100 m3 per hour) in both thevertical and horizontal directions from the pump position to thepoint of placing. Concrete pumps can be trailer or lorry mountedand are usually of a twin cylinder hydrau...

  • Page 216

    Placing Concrete ~ this activity is usually carried out by hand withthe objectives of filling the mould, formwork or excavated area tothe correct depth, working the concrete around any inserts orreinforcement and finally compacting the concrete to the requiredconsolidation. The compaction of conc...

  • Page 217

    Power Float † a hand-operated electric motor or petrol engine,surmounted over a mechanical surface skimmer. Machines areprovided with an interchangeable revolving disc and a set ofblades. These are used in combination to produce a smooth, denseand level surface finish to in-situ concrete beds.T...

  • Page 218

    4 SUBSTRUCTUREFOUNDATIONS † FUNCTION, MATERIALS AND SIZINGFOUNDATION BEDSSHORT BORED PILE FOUNDATIONSFOUNDATION TYPES AND SELECTIONPILED FOUNDATIONSRETAINING WALLSGABIONS AND MATTRESSESBASEMENT CONSTRUCTIONWATERPROOFING BASEMENTSEXCAVATIONSCONCRETE PRODUCTIONCOFFERDAMSCAISSONSUNDERPINNINGGROUND...

  • Page 219

    Foundations ~ the function of any foundation is to safely sustainand transmit to the ground on which it rests the combined dead,imposed and wind loads in such a manner as not to cause anysettlement or other movement which would impair the stability orcause damage to any part of the building.Subso...

  • Page 220

    Subsoil Movements ~ these are due primarily to changes in volumewhen the subsoil becomes wet or dry and occurs near the uppersurface of the soil. Compact granular soils such as gravel suffer verylittle movement whereas cohesive soils such as clay do suffer volumechanges near the upper surface. Si...

  • Page 221

    Trees ~ damage to foundations. Substructural damage to buildingscan occur with direct physical contact by tree roots. Morecommon is the indirect effect of moisture shrinkage or heave,particularly apparent in clay subsoils.Shrinkageismostevidentinlongperiodsofdryweather,compounded by moisture abst...

  • Page 222

    Trees ~ effect on foundations. Trees up to 30 m distance may havean effect on foundations, therefore reference to local authoritybuilding control policy should be undertaken before specifyingconstruction techniques.Traditional strip foundations are practically unsuited, but atexcavation depths up...

  • Page 223

    Trees ~ preservation orders (see page 123) may be waived by thelocal planning authority. Permission for tree felling is by formalapplication and will be considered if the proposed development is inthe economic and business interests of the community. However,tree removal is only likely to be acce...

  • Page 224

    Cracking in Walls ~ cracks are caused by applied forces whichexceed those that the building can withstand. Most cracking issuperficial, occurring as materials dry out and subsequently shrinkto reveal minor surface fractures of < 2 mm. These insignificantcracks can be made good with proprietary...

  • Page 225

    Foundation Materials ~ from page 190 one of the functions of afoundation can be seen to be the ability to spread its load evenlyover the ground on which it rests. It must of course be constructedof a durable material of adequate strength. Experience has shownthat the most suitable material is con...

  • Page 226

    213Foundation Types

  • Page 227

    214Foundation Types

  • Page 228

    Bed ~ a concrete slab resting on and supported by the subsoil,usually forming the ground floor surface. Beds (sometimes calledoversite concrete) are usually cast on a layer of hardcore which isused to make up the reduced level excavation and thus raise thelevel of the concrete bed to a position a...

  • Page 229

    Basic Sizing ~ the size of a foundation is basically dependent ontwo factors †1 . Load being transmitted, max 70 kN/m (dwellings up to 3 storeys).2. Bearing capacity of subsoil under proposed foundation.Bearing capacities for different types of subsoils may be obtainedfrom tables such as those ...

  • Page 230

    Max. total load onload bearing wall (kN/m)203040506070Ground typeGroundconditionFieldtestMinimum width (mm)RockNot inferiorto sandstone,limestone orfirm chalk.Requires amechanicaldevice toexcavate.At least equal tothe width of the wallGravelMediumdensityPick requiredto excavate.SandCompact50 mm s...

  • Page 231

    Typical procedure (for guidance only) †5.0 m 5.0 m 1.0 m 2.5 m 2.5 m 2.9 m 2.9 m 30° 30° 1 m wide strip foundation0.15 m x 0.5 m (assumed)Note: For roof pitch >30°, snow load = 0„75 kN/m2Dead + imposed load is, 26„56 kN + 7„80 kN = 34„36 kNGiven that the subsoil has a safe bearing...

  • Page 232

    Stepped Foundations ~ these are usually considered in the contextof strip foundations and are used mainly on sloping sites to reducethe amount of excavation and materials required to produce anadequate foundation.219Stepped Foundations

  • Page 233

    Concrete Foundations ~ concrete is a material which is strong incompression but weak in tension. If its tensile strength is exceededcracks will occur resulting in a weak and unsuitable foundation.One method of providing tensile resistance is to include in theconcrete foundation bars of steel as a...

  • Page 234

    Short Bored Piles ~ these are a form of foundation which aresuitable for domestic loadings and clay subsoils where groundmovements can occur below the 1„000 depth associated withtraditional strip and trench fill foundations. They can be usedwhere trees are planted close to a new building since ...

  • Page 235

    Simple Raft Foundations ~ these can be used for lightly loadedbuildings on poor soils or where the top 450 to 600 mm of soil isoverlaying a poor quality substrata.Typical Details ~cavity insulation external wall floor screed rigid insulation damp-proof membrane damp-proof course damp-proof cavity...

  • Page 236

    Foundation Design Principles ~ the main objectives of foundationdesign are to ensure that the structural loads are transmitted tothe subsoil(s) safely, economically and without any unacceptablemovement during the construction period and throughout theanticipated life of the building or structure....

  • Page 237

    Strip Foundations ~ these are suitable for most subsoils and lightstructural loadings such as those encountered in low to medium risedomestic dwellings where mass concrete can be used. Reinforcedconcrete is usually required for all other situations.224Foundation Types and Selection

  • Page 238

    Pad Foundations ~ suitable for most subsoils except loose sands,loosegravelsandfilledareas.Padfoundationsareusuallyconstructed of reinforced concrete and where possible are squarein plan.225Foundation Types and Selection

  • Page 239

    Raft Foundations ~ these are used to spread the load of thesuperstructure over a large base to reduce the load per unit areabeing imposed on the ground and this is particularly useful wherelow bearing capacity soils are encountered and where individualcolumn loads are heavy.226Foundation Types an...

  • Page 240

    Cantilever Foundations ~ these can be used where it is necessaryto avoid imposing any pressure on an adjacent foundation orunderground service.227Foundation Types and Selection

  • Page 241

    Piled Foundations ~ these can be defined as a series of columnsconstructed or inserted into the ground to transmit the load(s) ofa structure to a lower level of subsoil. Piled foundations can beused when suitable foundation conditions are not present at ornear ground level making the use of deep ...

  • Page 242

    Replacement Piles ~ these are often called bored piles since theremoval of the spoil to form the hole for the pile is always carriedout by a boring technique. They are used primarily in cohesivesubsoils for the formation of friction piles and when forming pilefoundations close to existing buildin...

  • Page 243

    Percussion Bored Piles230Piled Foundations

  • Page 244

    Flush Bored Piles231Piled Foundations

  • Page 245

    Small Diameter Rotary Bored Piles232Piled Foundations

  • Page 246

    Large Diameter Rotary Bored Piles233Piled Foundations

  • Page 247

    Continuous Flight Auger Bored PilesTypical Details ~kelly barpulleys suspension armCompleted pileshaft as shownon page 232hydraulic ramtrackedpowerunitstabilisermobile kellybar drivekelly bardrive guideflight augerauger guidecollarStandard pile diameters are 300, 450 and 600 mm. Depth of borehole...

  • Page 248

    Grout Injection Piling ~A variation of continuous flight auger bored piling that uses anopen ended hollow core to the flight. After boring to the requireddepth, high slump concrete is pumped through the hollow stem asthe auger is retracted. Spoil is displaced at the surface andremoved manually. I...

  • Page 249

    Displacement Piles ~ these are often called driven piles since theyare usually driven into the ground displacing the earth around thepileshaft.Thesepilescanbeeitherpreformedorpartiallypreformed if they are not cast in-situ and are available in a widevariety of types and materials. The pile or for...

  • Page 250

    Timber Piles ~ these are usually square sawn and can be used forsmall contracts on sites with shallow alluvial deposits overlying asuitable bearing strata (e.g. river banks and estuaries.) Timber pilesare percussion driven.237Piled Foundations

  • Page 251

    Preformed Concrete Piles ~ variety of types available which aregenerally used on medium to large contracts of not less thanone hundred piles where soft soil deposits overlie a firmer strata.These piles are percussion driven using a drop or single actinghammer.238Piled Foundations

  • Page 252

    Preformed Concrete Piles † jointing with a peripheral steel splicingcollar as shown on the preceding page is adequate for mostconcentrically or directly loaded situations. Where very long pilesare to be used and/or high stresses due to compression, tensionand bending from the superstructure or ...

  • Page 253

    Steel Box and `H' Sections ~ standard steel sheet pile sections canbe used to form box section piles whereas the `H' section piles arecut from standard rolled sections. These piles are percussion drivenand are used mainly in connection with marine structures.Steel Screw Piles ~ rotary driven and ...

  • Page 254

    Steel Tube Piles ~ used on small to medium size contracts formarine structures and foundations in soft subsoils over a suitablebearing strata. Tube piles are usually bottom driven with aninternal drop hammer. The loading can be carried by the tube alonebut it is usual to fill the tube with mass c...

  • Page 255

    Partially Preformed Piles ~ these are composite piles of precastconcrete and in-situ concrete or steel and in-situ concrete (seepage 241). These percussion driven piles are used on medium tolarge contracts where bored piles would not be suitable owing torunning water or very loose soils.242Piled ...

  • Page 256

    Driven In-situ Piles ~ used on medium to large contracts as analternative to preformed piles particularly where final length ofpile is a variable to be determined on site.243Piled Foundations

  • Page 257

    Cast In-situ Piles ~ an alternative to the driven in-situ piles (seepage 243)244Piled Foundations

  • Page 258

    Piling Hammers ~ these are designed to deliver an impact blow tothe top of the pile to be driven. The hammer weight and dropheight is chosen to suit the pile type and nature of subsoil(s)through which it will be driven. The head of the pile being driven isprotected against damage with a steel hel...

  • Page 259

    Double Acting Hammers ~ theseconsist of a cast iron cylinderwhich remains stationary on thepile head whilst a ram poweredby steam or compressed air forbothupanddownstrokesdelivers a series of rapid blowswhich tends to keep the pile onthemoveduringdriving.Theblow delivered is a smaller forcethan t...

  • Page 260

    Pile Caps ~ piles can be used singly to support the load but oftenit is more economical to use piles in groups or clusters linkedtogether with a reinforced concrete cap. The pile caps can also belinked together with reinforced concrete ground beams.The usual minimum spacing for piles is:-1 . Fric...

  • Page 261

    Retaining Walls ~ the major function of any retaining wall is to actas on earth retaining structure for the whole or part of its heighton one face, the other being exposed to the elements. Most smallheightretainingwallsarebuiltentirelyofbrickworkoracombination of brick facing and blockwork or mas...

  • Page 262

    Small Height Retaining Walls ~ retaining walls must be stable andthe usual rule of thumb for small height brick retaining walls is forthe height to lie between 2 and 4 times the wall thickness.Stability can be checked by applying the middle third rule †249Retaining Walls up to 1 m High---2

  • Page 263

    Retaining Walls up to 6„000 high ~ these can be classified asmedium height retaining walls and have the primary function ofretaining soils at an angle in excess of the soil's natural angle ofrepose. Walls within this height range are designed to provide thenecessary resistance by either their o...

  • Page 264

    Earth Pressures ~ these can take one of two forms namely:-1 . Active Earth Pressures † these are those pressures whichtend to move the wall at all times and consist of the wedgeof earth retained plus any hydrostatic pressure. The lattercan be reduced by including a subsoil drainage system behin...

  • Page 265

    Mass Retaining Walls ~ these walls rely mainly on their own massto overcome the tendency to slide forwards. Mass retaining wallsare not generally considered to be economic over a height of 1„800when constructed of brick or concrete and 1„000 high in the caseof natural stonework. Any mass reta...

  • Page 266

    253Medium Height Retaining Walls

  • Page 267

    Cantilever Retaining Walls ~ these are constructed of reinforcedconcrete with an economic height range of 1„200 to 6„000. Theywork on the principles of leverage where the stem is designed as acantilever fixed at the base and base is designed as a cantileverfixed at the stem. Several formats a...

  • Page 268

    Formwork ~ concrete retaining walls can be cast in one of threeways † full height; climbing (page 256) or against earth face (page257).Full Height Casting ~ this can be carried out if the wall is to becast as a freestanding wall and allowed to cure and gain strengthbefore the earth to be retain...

  • Page 269

    Climbing Formwork or Lift Casting ~ this method can be employedon long walls, high walls or where the amount of concrete whichcan be placed in a shift is limited.256Medium Height Retaining Walls

  • Page 270

    Casting Against Earth Face ~ this method can be an adaptation ofthe full height or climbing formwork systems. The latter uses asteel wire loop tie fixing to provide the support for the second andsubsequent lifts.257Medium Height Retaining Walls

  • Page 271

    Masonry units † these are an option where it is impractical orcost-ineffective to use temporary formwork to in-situ concrete.Exposed brick or blockwork may also be a preferred finish. Inaddition to being a structural component, masonry units providepermanent formwork to reinforced concrete pour...

  • Page 272

    Construction † a reinforced concrete base is cast with projectingsteel bars accurately located for vertical continuity. The wall maybe built solid, e.g. Quetta bond, with voids left around the bars forsubsequent grouting. Alternatively, the wall may be of wide cavityconstruction,wherethe expose...

  • Page 273

    Crib Retaining Walls † a system of pre-cast concrete or treatedtimbercomponentscomprisingheadersandstretcherswhichinterlock to form a three-dimensional framework. During assemblythe framework is filled with graded stone to create sufficient massto withstand ground pressures.batter1:4 timber1:6...

  • Page 274

    SoilNailing~acosteffectivegeotechnicprocessusedforretaininglargesoilslopes,notablyhighwayandrailwayembankments.Function ~ after excavating and removing the natural slopesupport, the remaining wedge of exposed unstable soil is pinned ornailed back with tendons into stable soil behind the potential...

  • Page 275

    Gabion~atypeofretainingwallproducedfromindividualrectangularboxesmadefrompanelsofwiremesh,dividedinternally and filled with stones. These units are stacked andoverlapped (like stretcher bonded masonry) and applied in severallayers or courses to retained earth situations. Typical sizes, 1„0 mlon...

  • Page 276

    Design of Retaining Walls ~ this should allow for the effect ofhydrostatics or water pressure behind the wall and the pressurecreated by the retained earth (see page 251). Calculations arebased on a 1 m unit length of wall, from which it is possible toascertain:263Retaining Walls---Design Calcula...

  • Page 277

    A graphical design solution, to determine the earth thrust (P)behind a retaining wall. Data from previous page:h = 3„300 m =30°w = 1500 kg/m3Wall height is drawn to scale and plane of repose plotted. Thewedge section is obtained by drawing the plane of rupture throughan angle bisecting the pla...

  • Page 278

    Open Excavations ~ one of the main problems which can beencountered with basement excavations is the need to providetemporary support or timbering to the sides of the excavation.This can be intrusive when the actual construction of the basementfloor and walls is being carried out. One method is t...

  • Page 279

    Perimeter Trench Excavations ~ in this method a trench wideenough for the basement walls to be constructed is excavated andsupported with timbering as required. It may be necessary forrunners or steel sheet piling to be driven ahead of the excavationwork.Thismethodcanbeusedwhereweaksubsoilsareenc...

  • Page 280

    Complete Excavation ~ this method can be used in firm subsoilswhere the centre of the proposed basement can be excavated firstto enable the basement slab to be cast thus giving protection tothe subsoil at formation level. The sides of excavation to theperimeter of the basement can be supported fr...

  • Page 281

    Excavating Plant ~ the choice of actual pieces of plant to be usedin any construction activity is a complex matter taking intoaccountmanyfactors.Specificdetailsofvarioustypesofexcavators are given on pages 175 to 179. At this stage it is onlynecessary to consider basic types for particular operat...

  • Page 282

    Basement Construction ~ in the general context of buildings abasement can be defined as a storey which is below the groundstorey and is therefore constructed below ground level. Mostbasements can be classified into one of three groups:-269Basement Construction

  • Page 283

    Deep Basement Construction ~ basements can be constructedwithin a cofferdam or other temporary supported excavation (seeBasement Excavations on pages 265 to 267) up to the point whenthese methods become uneconomic, unacceptable or both due tothe amount of necessary temporary support work. Deep ba...

  • Page 284

    271Basement Construction

  • Page 285

    Waterproofing Basements ~ basements can be waterproofed by oneof three basic methods namely:-1 . Use of dense monolithic concrete walls and floor2. Tanking techniques (see pages 274 & 275)3. Drained cavity system (see page 276)Dense Monolithic Concrete † the main objective is to form a wate...

  • Page 286

    Joints ~ in general these are formed in basement constructions toprovide for movement accommodation (expansion joints) or tocreate a convenient stopping point in the construction process(construction joints). Joints are lines of weakness which will leakunless carefully designed and constructed th...

  • Page 287

    Mastic Asphalt Tanking ~ the objective of tanking is to provide acontinuous waterproof membrane which is applied to the base slaband walls with complete continuity between the two applications.The tanking can be applied externally or internally accordingto the circumstances prevailing on site. Al...

  • Page 288

    Internal Mastic Asphalt Tanking ~ this method should only beadopted if external tanking is not possible since it will not giveprotection to the main structure and unless adequately loaded maybe forced away from the walls and/or floor by hydrostaticpressure. To be effective the horizontal and vert...

  • Page 289

    Drained Cavity System ~ this method of waterproofing basementscan be used for both new and refurbishment work. The basicconcept is very simple in that it accepts that a small amount ofwater seepage is possible through a monolithic concrete wall andthe best method of dealing with such moisture is ...

  • Page 290

    Basements benefit considerably from the insulating properties ofthe surrounding soil. However, that alone is insufficient to satisfythe typical requirements for wall and floor U-values of 0„35 and0„30 W/m2K, respectively.Refurbishment of existing basements may include insulation withindry lin...

  • Page 291

    Excavation ~ to hollow out † in building terms to remove earth toform a cavity in the ground.NB. Water in Excavations † this should be removed since it can:~1 . Undermine sides of excavation.2. Make it impossible to adequately compact bottom of excavationto receive foundations.3. Cause puddli...

  • Page 292

    Trench Excavations~ narrow excavationsprimarily for stripfoundations and buried services † excavation can be carried out byhand or machine.279Excavations

  • Page 293

    Excavations up to 2.5 m deep---Processes280

  • Page 294

    All subsoils have different abilities in remaining stable duringexcavation works. Most will assume a natural angle of repose orrest unless given temporary support. The presence of groundwater apart from creating difficult working conditions can have anadverse effect on the subsoil's natural angle...

  • Page 295

    Temporary Support ~ in the context of excavations this is calledtimbering irrespective of the actual materials used. If the sides ofthe excavation are completely covered with timbering it is knownas close timbering whereas any form of partial covering is calledopen timbering.An adequate supply of...

  • Page 296

    Poling Boards ~ a form of temporary support which is placed inposition against the sides of excavation after the excavation workhasbeencarriedout.Polingboardsareplacedatcentresaccording to the stability of the subsoils encountered.Runners ~ a form of temporary support which is driven intoposition...

  • Page 297

    shape, surface texture and grading (distributionshape, surface texture and grading (distributionof particle sizes) are factors which influenceof particle sizes) are factors which influencethe workability and strength of a concretethe workability and strength of a concretemix. Fine aggregates are ...

  • Page 298

    Cement ~ whichever type of cement is being used it must beproperly stored on site to keep it in good condition. The cementmust be kept dry since contact with any moisture whether director airborne could cause it to set. A rotational use system shouldbe introduced to ensure that the first batch of...

  • Page 299

    Concrete Batching ~ a batch is one mixing of concrete and can becarried out by measuring the quantities of materials required byvolume or weight. The main aim of both methods is to ensure thatall consecutive batches are of the same standard and quality.Volume Batching ~ concrete mixes are often q...

  • Page 300

    Weight or Weigh Batching ~ this is a more accurate method ofmeasuring materials for concrete than volume batching since itreducesconsiderablytheriskofvariationbetweendifferentbatches. The weight of sand is affected very little by its dampnesswhich in turn leads to greater accuracy in proportionin...

  • Page 301

    Concrete ~ a composite with many variables, represented bynumerousgradingswhichindicatecomponents,qualityandmanufacturing control.Grade mixes: C7.5, C10, C15, C20, C25, C30, C35, C40, C45, C50,C55, and C60; F3, F4 and F5; IT2, IT2.5, and IT3.C = Characteristic compressiveF = FlexuralIT = Indirect...

  • Page 302

    Concrete Supply ~ this is usually geared to the demand or the rateat which the mixed concrete can be placed. Fresh concrete shouldalways be used or placed within 30 minutes of mixing to preventany undue drying out. Under no circumstances should more waterbe added after the initial mixing.Ref. BS ...

  • Page 303

    Cofferdams ~ these are temporary enclosures installed in soil orwater to prevent the ingress of soil and/or water into theworking area with the cofferdam. They are usually constructedfrom interlocking steel sheet piles which are suitably braced ortied back with ground anchors. Alternatively a cof...

  • Page 304

    Steel Sheet Piling ~ apart from cofferdam work steel sheet can beused as a conventional timbering material in excavations and toform permanent retaining walls. Three common formats of steelsheet piles with interlocking joints are available with a range ofsection sizes and strengths up to a usual ...

  • Page 305

    Caissons ~ these are box-like structures which are similar inconcept to cofferdams but they usually form an integral part ofthe finished structure. They can be economically constructed andinstalled in water or soil where the depth exceeds 18„000. Thereare 4 basic types of caisson namely:-1 . Bo...

  • Page 306

    Pneumatic Caissons ~ these are sometimes called compressed aircaissons and are similar in concept to open caissons. They can beused in difficult subsoil conditions below water level and have apressurised lower working chamber to provide a safe dry workingarea. Pneumatic caissons can be made of co...

  • Page 307

    Underpinning ~ the main objective of most underpinning work is totransfer the load carried by a foundation from its existing bearinglevel to a new level at a lower depth. Underpinning techniques canalsobeusedtoreplaceanexistingweakfoundation.Anunderpinning operation may be necessary for one or mo...

  • Page 308

    Underpinning to Walls ~ to prevent fracture, damage or settlementof the wall(s) being underpinned the work should always be carriedout in short lengths called legs or bays. The length of these bayswill depend upon the following factors:-1. Total length of wall to be underpinned.2. Wall loading.3....

  • Page 309

    296Underpinning

  • Page 310

    Jack Pile Underpinning ~ this method can be used when the depthof a suitable bearing capacity subsoil is too deep to maketraditional underpinning uneconomic. Jack pile underpinning is quiet,vibration free and flexible since the pile depth can be adjusted tosuit subsoil conditions encountered. The...

  • Page 311

    Needle and Pile Underpinning ~ this method of underpinning can beused where the condition of the existing foundation is unsuitablefor traditional or jack pile underpinning techniques. The brickworkabove the existing foundation must be in a sound condition sincethis method relies on the `arching e...

  • Page 312

    `Pynford' Stool Method of Underpinning ~ this method can be usedwhere the existing foundations are in a poor condition and itenables the wall to be underpinned in a continuous run without theneed for needles or shoring. The reinforced concrete beam formedby this method may well be adequate to spr...

  • Page 313

    Root Pile or Angle Piling ~ this is a much simpler alternative totraditionalunderpinningtechniques,applyingmodernconcretedrilling equipment to achieve cost benefits through time saving. Theprocess is also considerably less disruptive, as large volumes ofexcavation are avoided. Where sound bearing...

  • Page 314

    Underpinning Columns ~ columns can be underpinned in the somemanner as walls using traditional or jack pile methods after thecolumns have been relieved of their loadings. The beam loads canusually be transferred from the columns by means of dead shoresand the actual load of the column can be tran...

  • Page 315

    Classification of Water ~ water can be classified by its relativeposition to or within the ground thus †Problems of Water in the Subsoil ~1 . A high water table could cause flooding during wet periods.2. Subsoil water can cause problems during excavation works byits natural tendency to flow int...

  • Page 316

    Permanent Exclusion ~ this can be defined as the insertion of animpermeable barrier to stop the flow of water within the ground.Temporary Exclusion ~ this can be defined as the lowering of thewater table and within the economic depth range of 1„500 can beachieved by subsoil drainage methods, fo...

  • Page 317

    Jetted Sumps ~ this method achieves the same objectives as thesimple sump methods of dewatering (previous page) but it willprevent the soil movement associated with this and other opensump methods. A borehole is formed in the subsoil by jetting ametal tube into the ground by means of pressurised ...

  • Page 318

    Wellpoint Systems ~ method of lowering the water table to aposition below the formation level to give a dry working area. Thebasic principle is to jet into the subsoil a series of wellpoints whichare connected to a common header pipe which is connected to avacuum pump. Wellpoint systems are suita...

  • Page 319

    306Ground Water Control---Temporary Exclusion

  • Page 320

    Thin Grouted Membranes ~ these are permanent curtain or cut-offnon-structural walls or barriers inserted in the ground to enclosethe proposed excavation area. They are suitable for silts andsands and can be installed rapidly but they must be adequatelysupported by earth on both sides. The only li...

  • Page 321

    Contiguous or Secant Piling ~ this forms a permanent structuralwall of interlocking bored piles. Alternate piles are bored and castby traditional methods and before the concrete has fully hardenedthe interlocking piles are bored using a toothed flight auger. Thissystem is suitable for most types ...

  • Page 322

    Diaphragm Walls ~ these are structural concrete walls which canbecastin-situ(usuallybythebentoniteslurrymethod)orconstructed using precast concrete components (see next page).They are suitable for most subsoils and their installation generatesonly a small amount of vibration and noise making them...

  • Page 323

    Precast Concrete Diaphragm Walls ~ these walls have the someapplications as their in-situ counterparts and have the advantagesof factory produced components but lack the design flexibility ofcast in-situ walls. The panel or post and panel units are installed ina trench filled with a special mixtu...

  • Page 324

    Grouting Methods ~ these techniques are used to form a curtain orcut off wall in high permeability soils where pumping methods couldbe uneconomic. The curtain walls formed by grouting methods arenon-structural therefore adequate earth support will be requiredand in some cases this will be a dista...

  • Page 325

    Ground Freezing Techniques ~ this method is suitable for all typesof saturated soils and rock and for soils with a moisture content inexcess of 8% of the voids. The basic principle is to insert into theground a series of freezing tubes to form an ice wall thus creatingan impermeable barrier. The ...

  • Page 326

    Soil Investigation ~ before a decision is made as to the type offoundation which should be used on any particular site a soilinvestigation should be carried out to establish existing groundconditions and soil properties. The methods which can be employedtogetherwithothersourcesofinformationsuchas...

  • Page 327

    Ground Vibration ~ the objective of this method is to strengthenthe existing soil by rearranging and compacting coarse granularparticles to form stone columns with the ground. This is carriedout by means of a large poker vibrator which has an effectivecompacting radius of 1„500 to 2„700. On l...

  • Page 328

    Sand Compaction † applied to non-cohesive subsoils where thegranular particles are rearranged into a denser condition by pokervibration.The crane-suspended vibrating poker is water-jetted into theground using a combination of self weight and water displacementof the finer soil particles to pene...

  • Page 329

    DynamicCompaction~thismethodofgroundimprovementconsists of dropping a heavy weight from a considerable height andis particularly effective in granular soils. Where water is present inthe subsoil, trenches should be excavated to allow the water toescape and not collect in the craters formed by the...

  • Page 330

    Jet Grouting ~ this is a means of consolidating ground by loweringinto preformed bore holes a monitor probe. The probe is rotatedand the sides of the bore hole are subjected to a jet of pressurisedwater and air from a single outlet which enlarges and compactsthe bore hole sides. At the same time ...

  • Page 331

    Green-Field † land not previously built upon. Usually part of the`green†belt'surroundingurbanareas,designatedinappropriatefor development in order to preserve the countryside. Limiteddevelopment for agricultural purposes only may be permitted on`green-belt' land.Brown-Field † derelict land ...

  • Page 332

    Thetraditionallow-technologymethodfordealingwithcontaminated sites has been to excavate the soil and remove it toplaces licensed for depositing. However, with the increase inbuilding work on brown-field sites, suitable dumps are becomingscarce. Added to this is the reluctance of ground operators ...

  • Page 333

    BIOLOGICALPhytoremediation † the removal of contaminants by plants whichwill absorb harmful chemicals from the ground. The plants aresubsequently harvested and destroyed. A variant uses fungaldegradation of the contaminants.Bioremediation † stimulating the growth of naturally occurringmicrobe...

  • Page 334

    5 SUPERSTRUCTURE † 1CHOICE OF MATERIALSBRICK AND BLOCK WALLSBRICK BONDINGSPECIAL BRICKS AND APPLICATIONSCAVITY WALLSDAMP-PROOF COURSESGAS RESISTANT MEMBRANESARCHES AND OPENINGSWINDOWS, GLASS AND GLAZINGDOMESTIC AND INDUSTRIAL DOORSTIMBER FRAME CONSTRUCTIONRENDERING AND CLADDING EXTERNAL WALLSTI...

  • Page 335

    STAGE 1Consideration to be given to the following:~1 . Building type and usage.2. Building owner's requirements and preferences.3. Local planning restrictions.4. Legal restrictions and requirements.5. Site restrictions.6. Capital resources.7. Future policy in terms of maintenance and adaptation.3...

  • Page 336

    Bricks ~ these are walling units within a length of 337„5 mm, a widthof 225 mm and a height of 112„5 mm. The usual size of bricks incommon use is length 215 mm, width 102„5 mm and height 65 mm andlike blocks they must be laid in a definite pattern or bond if theyare to form a structural wal...

  • Page 337

    Typical Details ~Bonding ~ an arrangement of bricks in a wall, column or pier laidto a set pattern to maintain an adequate lap.Purposes of Brick Bonding ~1 . Obtain maximum strength whilst distributing the loads to becarried throughout the wall, column or pier.2. Ensure lateral stability and resi...

  • Page 338

    English Bond ~ formed by laying alternate courses of stretchersand headers it is one of the strongest bonds but it will requiremore facing bricks than other bonds (89 facing bricks per m2)Typical Example ~325Brick Bonding---English Bond

  • Page 339

    Flemish Bond ~ formed by laying headers and stretchers alternatelyin each course. Not as strong as English bond but is considered tobe aesthetically superior uses less facing bricks. (79 facing bricksper m2)Typical Example326Brick Bonding---Flemish Bond

  • Page 340

    327Brick Bonding---Special Bonds

  • Page 341

    Stack Bonding † the quickest, easiest and most economical bond tolay, as there is no need to cut bricks or to provide special sizes.Visually the wall appears unbonded as continuity of vertical jointsis structurally unsound, unless wire bed-joint reinforcement isplaced in every horizontal course...

  • Page 342

    Attached Piers ~ the main function of an attached pier is to givelateral support to the wall of which it forms part from the base tothe top of the wall. It also has the subsidiary function of dividing awall into distinct lengths whereby each length can be considered asa wall. Generally walls must...

  • Page 343

    Attached piers as applied to 1/2 brick (90 mm min.) thick walls ~• MajoropeningsAandBarepermittedinonewallonly.Aggregate width is 5 m maximum. Height not greater than 2.1 m.No other openings within 2 m.• Other walls not containing a major opening can have smalleropenings of maximum aggregate ...

  • Page 344

    Construction of half-brick and 100 mm thick solid concrete blockwalls (90 mm min.) with attached piers, has height limitations tomaintain stability. The height of these buildings will vary dependingon the roof profile; it should not exceed the lesser value in thefollowing examples ~Note: All dime...

  • Page 345

    The appearance of a building can be significantly influenced by themortar finishing treatment to masonry. Finishing may be achievedby jointing or pointing.Jointing † the finish applied to mortar joints as the work proceeds.Pointing † the process of removing semi-set mortar to a depth ofabout ...

  • Page 346

    Specials † these are required for feature work and application tovarious bonds, as shown on the preceding pages. Bonding is notsolely for aesthetic enhancement. In many applications, e.g. Englishbonded manhole walls, the disposition of bricks is to maximise wallstrength and integrity. In a maso...

  • Page 347

    Brickwork can be repetitive and monotonous, but with a littleimagination and skilled application it can be a highly decorative artform. Artistic potential is made possible by the variety of naturallyoccurring brick colours, textures and finishes, the latter oftenapplied as a sanding to soft clay ...

  • Page 348

    Plinths † used as a projecting feature to enhance external wallappearance at its base. The exposed projection determines thatonly frost-proof quality bricks are suitable and that recessed orraked out joints which could retain water must be avoided.Typical external wall base †Corbel†aproject...

  • Page 349

    Corbel†atypeofinvertedplinth,generally located atthe higher levels of abuilding to create afeature.Atypicalexampleisquarterbonded headers as adetail below windowopenings.Dentil Coursing † a variation on continuous corbelling wherealternative headers project. This is sometimes referred to as t...

  • Page 350

    Blocks ~ these are walling units exceeding in length, width orheight the dimensions specified for bricks in BS EN 772-16. Precastconcrete blocks should comply with the recommendations set outin BS 6073-2 and BS EN 771-3. Blocks suitable for external solidwalls are classified as loadbearing and ar...

  • Page 351

    Cavity Walls ~ these consist of an outer brick or block leaf or skinseparated from an inner brick or block leaf or skin by an air spacecalled a cavity. These walls have better thermal insulation andweather resistance properties than a comparable solid brick orblock wall and therefore are in gener...

  • Page 352

    Minimum requirements ~Thickness of each leaf, 90 mm.Width of cavity, 50 mm.Wall ties at 2.5/m2 (see previous page).Compressive strength of bricks, 5 N/mm2 up to two storeys.*Compressive strength of blocks, 2.8 N/mm2 up to two storeys.** For work between the foundation and the surface a 7 N/mm2min...

  • Page 353

    *Min. compressive strength depends on building height and loading. See Building Regulations AD A: Section 2C (Diagram 9). cavity leaves to be not less than 90 mm thick cavity to extend at least 225 mm below the lowest dpc outer leaf of selected facing bricks dpc ground level TRADITIONAL CONSTRUCT...

  • Page 354

    Parapet ~ a low wall projecting above the level of a roof, bridgeor balcony forming a guard or barrier at the edge. Parapets areexposed to the elements justifying careful design and constructionfor durability.Typical Details ~Ref. BS EN 771-1: Specification for (clay) masonry units.*``severe'' ex...

  • Page 355

    Historically, finned or buttressed walls have been used to providelateral support to tall single storey masonry structures such aschurchesandcathedrals.Modernapplicationsaresimilarinprinciple and include theatres, gymnasiums, warehouses, etc. Wherespace permits, they are an economic alternative t...

  • Page 356

    Masonry diaphragm walls are an alternative means of constructingtall, single storey buildings such as warehouses, sports centres,churches, assembly halls, etc. They can also be used as retainingand boundary walls with planting potential within the voids. Thesevoids may also be steel reinforced an...

  • Page 357

    Function † the primary function of any damp-proof course (dpc) ordamp-proof membrane (dpm) is to provide an impermeable barrierto the passage of moisture. The three basic ways in which damp-proof courses are used is to:-1 . Resist moisture penetration from below (rising damp).2. Resist moisture...

  • Page 358

    Building Regulations, Approved Document C2, Section 5:A wall may be built with a `damp-proof course of bituminous material,polyethylene, engineering bricks or slates in cement mortar, or anyother material that will prevent the passage of moisture.'MaterialRemarksLeadBS EN 12588Code 4 (1„8mm)May...

  • Page 359

    Refs:BS 743: Specification for materials for damp-proof courses.BS 5628-3: Code of practice for the use of masonry. Materials andcomponents, design and workmanship.BS 8102: Code of practice for protection of structures againstwater from the ground.BS 8215: Code of practice for design and installa...

  • Page 360

    Materials † Silicone solutions in organic solvent.Aluminium stearate solutions.Water soluble silicone formulations (siliconates).Methods † High pressure injection (0„70 † 0„90 MPa) solvent based.Low pressure injection (0„15 † 0„30 MPa) water based.Gravity feed, water based.Inserti...

  • Page 361

    Injection mortars † 19 mm diameter holes are bored from both sidesof a wall, at the appropriate level and no more than 230 mm aparthorizontally, to a depth equating to three-fifths of the wallthickness. They should be inclined downwards at an angle of 20 to30°. The drill holes are flushed out ...

  • Page 362

    In addition to damp-proof courses failing due to deterioration ordamage, they may be bridged as a result of:* Faults occurring during construction.* Work undertaken after construction, withdisregard for the damp-proof course.Typical examples ~349Bridging of Damp-Proof Courses

  • Page 363

    Thermal insulation regulations may require insulating dpcs toprevent cold bridging around window and door openings in cavitywall construction (see pages 488 and 489). By locating a verticaldpc with a bonded insulant at the cavity closure, the dpc preventspenetration of dampness from the outside, ...

  • Page 364

    Penetrating Gases ~ Methane and RadonMethane † methane is produced by deposited organic materialdecaying in the ground. It often occurs with carbon dioxide andtraces of other gases to form a cocktail known as landfill gas. Ithasbecomeanacuteprobleminrecentyears,asplanningrestrictions on `green-...

  • Page 365

    cavity wall insulated as required stepped cavity tray/dpc weep hole air brick dpc sealed joint screed insulation LDPE membrane min. 1200 gauge (0.3 mm)PASSIVE Suspended concrete floor pre-cast reinforced concrete floor min. 150 mm LDPE membrane finished slab level reinforced concrete slab Solid f...

  • Page 366

    Calculated Brickwork ~ for small and residential buildings up to threestoreys high the sizing of load bearing brick walls can be taken fromdata given in Section 2C of Approved Document A. The alternativemethods for these and other load bearing brick walls are given in:BS 5628-1: Code of practice ...

  • Page 367

    Strength of Bricks ~ due to the wide variation of the rawmaterials and methods of manufacture bricks can vary greatly intheircompressivestrength.Thecompressivestrengthofaparticular type of brick or batch of bricks is taken as thearithmetic mean of a sample of ten bricks tested in accordancewith t...

  • Page 368

    Slenderness Ratio ~ this is the relationship of the effective heightto the effective thickness thus:-Slenderness ratio ¼effective heighteffective thickness¼ htj> 27 see BS 5628Effective Height ~ this is the dimension taken to calculate theslenderness ratio as opposed to the actual height.Typ...

  • Page 369

    Lime ~ traditional mortars are a combination of lime, sand andwater. These mixes are very workable and have sufficient flexibilityto accommodate a limited amount of wall movement due tosettlement, expansion and contraction. The long term durability oflime mortarsispoor asthey can break downin the...

  • Page 370

    Ready mixed mortar ~ this is delivered dry for storage in purposemade silos with integral mixers as an alternative to site blendingand mixing. This ensures:* Guaranteed factory quality controlled product* Convenience* Mix consistency between batches* Convenient facility for satisfying variable de...

  • Page 371

    Supports Over Openings ~ the primary function of any supportover an opening is to carry the loads above the opening andtransmit them safely to the abutments, jambs or piers on bothsides. A support over an opening is usually required since theopening infilling such as a door or window frame will n...

  • Page 372

    Arch Construction ~ by the arrangement of the bricks or stones inan arch over an opening it will be self supporting once the jointingmaterial has set and gained adequate strength. The arch musttherefore be constructed over a temporary support until the archbecomes self supporting. The traditional...

  • Page 373

    The profile of an arch does not lend itself to simple positioning ofa damp proof course. At best, it can be located horizontally atupper extrados level. This leaves the depth of the arch andmasonrybelowthedpcvulnerabletodampness.Proprietarygalvanised or stainless steel cavity trays resolve this p...

  • Page 374

    The example in steel shown on the preceding page combinesstructural support with a damp proof course, without the need fortemporary support from a centre. Where traditional centring isretained, a lightweight preformed polypropylene cavity tray/dpccan be used. These factory made plastic trays are ...

  • Page 375

    Openings ~ these consist of a head, jambs and sill. Differentmethods can be used in their formation, all with the primaryobjective of adequate support around the void. Details relate toolder/existing construction and where thermal insulation is notcritical. Application limited † see pages 488 a...

  • Page 376

    Jambs ~ these may be bonded as in solid walls or unbonded as incavity walls. The latter must have some means of preventing theingress of moisture from the outer leaf to the inner leaf and hencethe interior of the building. Details as preceding page.Application limited † see pages 488 and 489.*R...

  • Page 377

    Sills ~ the primary function of any sill is to collect the rainwaterwhich has run down the face of the window or door and shed itclear of the wall below.Timber Sill 1, Cast Stone Subsill and Slate Sill have applicationslimited † see pages 488 and 489.Typical Sill details ~Ref. BS 5642-1: Sills ...

  • Page 378

    Traditional Construction †checked rebates or recessesin masonry solid walls wereoften provided at openingsto accommodate door andwindow frames. This detailwas used as a means tocomplement frame retentionandpreventweatherintrusion.Exposure Zones † checked reveal treatment is now required mainl...

  • Page 379

    A window must be aesthetically acceptable in the context ofbuilding design and surrounding environmentWindows should be selected or designed to resist wind loadings, beeasy to clean and provide for safety and security. They should besited to provide visual contact with the outside.Habitable upper...

  • Page 380

    367Windows---Conventional Types

  • Page 381

    368Timber Casement Windows

  • Page 382

    The standard range of casement windows used in the UK was derivedfrom the English Joinery Manufacturer's Association (EJMA) designsof some 50 years ago. These became adopted in BS 644: Timberwindows. Fully finished factory assembled windows of various types.Specification. A modified type is shown...

  • Page 383

    Metal Windows ~ these can be obtained in steel (BS 6510) or inaluminium alloy (BS 4873). Steel windows are cheaper in initial costthan aluminium alloy but have higher maintenance costs over theiranticipated life, both can be obtained fitted into timber subframes.Generally they give a larger glass...

  • Page 384

    Timber Windows ~ wide range of ironmongery available which canbe factory fitted or supplied and fixed on site.Metal Windows ~ ironmongery usually supplied with and factoryfitted to the windows.371Casement Windows---Ironmongery

  • Page 385

    Sliding Sash Windows ~ these are an alternative format to theconventional side hung casement windows and can be constructedas a vertical or double hung sash window or as a horizontal slidingwindow in timber, metal, plastic or in any combination of thesematerials. The performance and design functi...

  • Page 386

    Double Hung Sash Windows ~ these vertical sliding sash windowscome in two formats when constructed in timber. The weightbalanced format is shown on the preceding page, the alternativespring balanced type is illustrated below. Both formats are usuallydesigned and constructed to the recommendations...

  • Page 387

    Horizontally Sliding Sash Windows ~ these are an alternativeformat to the vertically sliding or double hung sash windows shownon pages 372 & 373 and can be constructed in timber, metal,plastic or combinations of these materials with single or doubleglazing. A wide range of arrangements are av...

  • Page 388

    Pivot Windows ~ like other windows these are available in timber,metal, plastic or in combinations of these materials.They can be constructed with centre jamb pivots enabling the sashto pivot or rotate in the horizontal plane or alternatively thepivots can be fixed in the head and sill of the fra...

  • Page 389

    Bay Windows ~ these can be defined as any window with side lightswhich projects in front of the external wall and is supported by asill height wall. Bay windows not supported by a sill height wall arecalled oriel windows. They can be of any window type, constructedfrom any of the usual window mat...

  • Page 390

    Schedules ~ the main function of a schedule is to collect together all the necessary information for aparticular group of components such as windows, doors and drainage inspection chambers. There is nostandard format for schedules but they should be easy to read, accurate and contain all the nece...

  • Page 391

    Window manufacturers identify their products with a notationthatcombinesfigureswithnumbers.Theobjectiveistosimplify catalogue entries, specification clauses and schedules.For example:head 1350 1770 fixed light sill vent-light left-hand casement as viewed from front right-hand casement as viewed f...

  • Page 392

    Glass ~ this material is produced by fusing together soda, lime andsilica with other minor ingredients such as magnesia and alumina.A number of glass types are available for domestic work and theseinclude:-Clear Float ~ used where clear undistorted vision is required.Available thicknesses range f...

  • Page 393

    Glazing ~ the act of fixing glass into a frame or surround. Indomestic work this is usually achieved by locating the glass in arebate and securing it with putty or beading and should be carriedout in accordance with the recommendations contained in the BS6262 series: Glazing for buildings.Timber ...

  • Page 394

    Double Glazing ~ as its name implies this is where two layers ofglass are used instead of the traditional single layer. Doubleglazing can be used to reduce the rate of heat loss throughwindows and glazed doors or it can be employed to reduce thesound transmission through windows. In the context o...

  • Page 395

    Secondary glazing of existing windows is an acceptable method forreducing heat energy losses at wall openings. Providing the existingwindows are in a good state of repair, this is a cost effective,simple method for upgrading windows to current energy efficiencystandards. In addition to avoiding t...

  • Page 396

    Low emissivity or ``Low E'' glass is specially manufactured with asurface coating to significantly improve its thermal performance.The surface coating has a dual function:1 . Allows solar short wave light radiation to penetrate a building.2. Reflects long wave heat radiation losses back into a bu...

  • Page 397

    Extrudedaluminiumprofiledsectionsaredesignedandmanufactured to create lightweight hollow window (and door)framing members.Finish † untreated aluminium is prone to surface oxidisation. Thiscan be controlled by paint application, but most manufacturersprovide a variable colour range of polyester ...

  • Page 398

    Inert gas fills ~ argon or krypton. Argon is generally used as it isthe least expensive and more readily available. Where krypton isused, the air gap need only be half that with argon to achieve asimilar effect. Both gases have a higher insulating value than airdue to their greater density.Densit...

  • Page 399

    Typical application ~* Hollow profiles manufactured with a closed cell insulant foam/expanded polystyrene core. Vertical section synthetic rubber sealing strip "L" shaped glazingbead/clip and seal/gasketglazed units of 3 mm glass and 12 mm gap or 4 mm glass and 16 mm gap air, argon or k...

  • Page 400

    Inthesecriticallocations,glazingmustsatisfyoneofthefollowing:-1 . Breakage to leave only a small opening with small detachableparticles without sharp edges.2. Disintegrating glass must leave only small detached pieces.3. Inherent robustness, e.g. polycarbonate composition. Annealedglass acceptabl...

  • Page 401

    Manifestation or Marking of Glass ~ another aspect of the criticallocationconceptwhichfrequentlyoccurswithcontemporaryglazed features in a building. Commercial premises such as openplan offices, shops and showrooms often incorporate large walledareas of uninterrupted glass to promote visual depth...

  • Page 402

    Glass blocks have been used for some time as internal featurepartitioning. They now include a variety of applications in externalwalls, where they combine the benefits of a walling unit with anatural source of light. They have also been used in paving toallow natural light penetration into baseme...

  • Page 403

    Mortar † dryer than for bricklaying as the blocks are non-absorbent. The general specification will include: White PortlandCement (BS EN 197-1), High Calcium Lime (BS EN 459-1) and Sand.The sand should be white quartzite or silica type. Fine silver sand isacceptable.Anintegralwaterproofingagent...

  • Page 404

    Doors ~ can be classed as external or internal. External doors areusually thicker and more robust in design than internal doors sincethey have more functions to fulfil.391Doors---Performance Requirements

  • Page 405

    External Doors ~ these are available in a wide variety of typesand styles in timber, aluminium alloy or steel. The majority ofexternal doors are however made from timber, the metal doorsbeing mainly confined to fully glazed doors such as `patio doors'.392Door Types

  • Page 406

    393Door Types

  • Page 407

    Door Frames ~ these are available for all standard external doorsand can be obtained with a fixed solid or glazed panel above adoor height transom. Door frames are available for doors openinginwardsoroutwards.Mostdoorframesaremadetotherecommendations set out in BS 4787: Internal and external wood...

  • Page 408

    Door Ironmongery ~ available in a wide variety of materials, stylesand finishers but will consist of essentially the same components:-Hinges or Butts † these are used to fix the door to its frame orlining and to enable it to pivot about its hanging edge.Locks, Latches and Bolts ~ the means of k...

  • Page 409

    Industrial Doors ~ these doors are usually classified by theirmethod of operation and construction. There is a very wide rangeof doors available and the choice should be based on the followingconsiderations:-1 . Movement - vertical or horizontal.2. Size of opening.3. Position and purpose of door(...

  • Page 410

    StraightSlidingDoors~thesedoorsareeasytooperate,economic to maintain and present no problems for the inclusion ofa wicket gate. They do however take up wall space to enable theleaves to be parked in the open position. The floor guide channelassociated with top hung doors can become blocked with d...

  • Page 411

    Sliding/Folding Doors ~ these doors are an alternative format tothe straight sliding door types and have the same advantages anddisadvantages except that the parking space required for theopened door is less than that for straight sliding doors. Sliding/folding are usually manually operated and c...

  • Page 412

    Shutters ~ horizontal folding shutters are similar in operation tosliding/folding doors but are composed of smaller leaves andpresent the same problems. Roller shutters however do not occupyany wall space but usually have to be fully opened for access.They can be manually operated by means of a p...

  • Page 413

    Crosswall Construction ~ this is a form of construction where loadbearing walls are placed at right angles to the lateral axis of thebuilding, the front and rear walls being essentially non-load bearingcladding. Crosswall construction is suitable for buildings up to 5storeys high where the floors...

  • Page 414

    Advantages of Crosswall Construction:-1 . Loadbearingandnon-loadbearingcomponentscanbestandardised and in same cases prefabricated giving fasterconstruction times.2. Fenestration between crosswalls unrestricted structurally.3. Crosswallsalthoughloadbearingneednotbeweatherresistant as is the case ...

  • Page 415

    System~comprisesqualitycontrolledfactoryproducedcomponents of plain reinforced concrete walls and prestressedconcrete hollow or solid core plank floors.Site Assembly ~ components are crane lifted and stacked manuallywith the floor panel edges bearing on surrounding walls. Temporarysupport will be...

  • Page 416

    Concept ~ a cost effective simple and fast site assembly systemusingload-bearingpartitionsandexternalwallstotransferverticalloadsfromfloorpanels.Thefloorprovideslateralstability by diaphragm action between the walls.Application ~ precast reinforced concrete crosswall constructionsystemsmaybeusedt...

  • Page 417

    Framing ~ an industry based pre-fabricated house manufacturingprocess permitting rapid site construction, with considerably fewersite operatives than traditional construction. This technique has along history of conventional practice in Scandinavia and NorthAmerica, but has only gained credibilit...

  • Page 418

    Notes:1 . Cavity barriers prevent fire spread.The principal locations are betweenelementsandcompartmentsofconstruction (see B. Regs. A.D. B3).2. Thermalbridgingthroughsolidframing may be reduced by using rigidEPS insulation and lighter `I' sectionmembersofplywoodororientedstrand board (OSB).405Ti...

  • Page 419

    Framing ~ comprising inner leaf wall panels of standard cold-formed galvanised steel channel sections as structural support,with a lined inner face of vapour check layer under plasterboard.These panels can be site assembled, but it is more realistic toorder them factory made. Panels are usually p...

  • Page 420

    Typical Details ~Eaves insulated cavity closer barrier (see Building Regs. A. D: B3, Section 6 [Vol. 1] and 9 [Vol. 2]) and plywood bracket bolted channel section truss storey height modular frame brickwork outer leaf channel section floor joists ground floor slab channel section truss members he...

  • Page 421

    Render ~ a mix of binder (cement) and fine aggregate (sand) withthe addition of water and lime or a plasticiser to make the mixworkable. Applied to walls as a decorative and/or waterproofingtreatment.Mix ratios ~ for general use, mix ratios are between 1 : 0.5 : 4†4.5and 1 : 1 : 5†6 of cement...

  • Page 422

    Number of coats (layers) and composition ~ in sheltered locations,one 10 mm layer is adequate for regular backgrounds. Elsewhere,two or possibly three separate applications are required toadequately weatherproof the wall and to prevent the brick orblock-work joints from ``grinning'' through. Rend...

  • Page 423

    Claddings to External Walls ~ external walls of block or timberframe construction can be clad with tiles, timber boards or plasticboard sections. The tiles used are plain roofing tiles with either astraight or patterned bottom edge. They are applied to thevertical surface in the same manner as ti...

  • Page 424

    External corner tiles are made to order as special fittings tostandard plain tiles. In effect they are tile and a halfs turnedthrough 90° (other angles can be made) and handed left or right,fixed alternately to suit the overlapping pattern.special one-pieceexternal corner tile38 × 25 battensver...

  • Page 425

    Internal corners are treated similarly to external corners by usingspecial tiles of approximately tile and a half overall dimensions,turned through 90° (or other specified angle) in the opposingdirection to external specials. These tiles are left and right handedandfixedalternatelytoverticalcour...

  • Page 426

    Some standard patterned bottom edge tiles ~165 mm165 mm265 mm265 mmDArrowheadArrowheadClubapprox. D/4Bullnose,beavertail or spadeBullnose andarrowheadBullnose andscallopedClub andscallopedScallopedor fishtailClubBullnoseScallopedNote: May also be used as a roof-tiling feature, generally in twoto ...

  • Page 427

    Ordinary splay cutting to roof verge ~Tile and a half tiles at theend of each course, cut totheundercloakcourseofroof tiling. A second nailhole can be drilled at thehead of each cut tile forsecure fixing to the parallelbatten.Winchester cutting to roof verge ~More attractive thanordinary splay cu...

  • Page 428

    Appearance and concept ~ a type of fake brickwork made up ofclay tiles side and head lapped over each other to create theimpression of brickwork, but without the expense. Joints/pointingcan be in lime mortar or left dry.History ~ originated during the 18th century, when they were usedquite freque...

  • Page 429

    Roofs--performanceRequirements416

  • Page 430

    Roofs ~ these can be classified as either:-Flat † pitch from 0° to 10°Pitched † pitch over 10°It is worth noting that for design purposes roof pitches over 70°are classified as walls.Roofs can be designed in many different forms and in combinationsof these forms some of which would not be...

  • Page 431

    418Basic Roof Forms

  • Page 432

    419Basic Roof Forms

  • Page 433

    Pitched Roofs ~ the primary functions of any domestic roof areto:-1 . Provideanadequatebarriertothepenetrationoftheelements.2. Maintain the internal environment by providing an adequateresistance to heat loss.A roof is in a very exposed situation and must therefore bedesigned and constructed in s...

  • Page 434

    hip rafterhiprafterridge boardridgeboardvalleyraftervalleyraftermainrafterpurlinpurlinjack orcripplerafterhipped endridge boardPurlins ~ guide to minimum size (mm) relative to span and spacing:Span (m)Spacing (m)1.752.252.752.0125¾ 75150¾ 75150¾ 1002.5150¾ 75175¾ 75175¾ 1003.0175¾ 100200¾...

  • Page 435

    422Timber Pitched Roofs up to 7.5 m Span--Types

  • Page 436

    423TimberPitchedRoofsupto7.5mSpan--Types

  • Page 437

    Roof Trusses ~ these are triangulated plane roof frames designed to give clear spans between the externalsupporting walls. They are usually prefabricated or partially prefabricated off site and are fixed at 1„800centres to support purlins which accept loads from the infill rafters.424TimberPitc...

  • Page 438

    Trussed Rafters ~ these are triangulated plane roof frames designed to give clear spans between the externalsupporting walls. They are delivered to site as a prefabricated component where they are fixed to the wallplates at 600 mm centres. Trussed rafters do not require any ridge board or purlins...

  • Page 439

    More economical for larger spans than with double rafters and ordinary purlins. Used where the sizeof purlins would be uneconomically large and/or an excessive number of struts, ties and hangerswould be requiredTop and bottom flanges/chords aretypically 100 × 100 mm or100 × 75 mm and struts100 ...

  • Page 440

    Gambrel roofs are double pitched with a break in the roof slope.The pitch angle above the break is less than 45° relative to thehorizontal, whilst the pitch angle below the break is greater.Generally, these angles are 30° and 60°.Gambrelsareusefulinprovidingmoreatticheadroomandfrequently incor...

  • Page 441

    Valley construction and associated pitched roofing is used:• to visually enhance an otherwise plain roof structure.• where the roof plan turns through an angle (usually 90°)tofollow the building layout or a later extension.• at the intersection of main and projecting roofs above a baywindo...

  • Page 442

    Sprockets may be provided at the eaves to reduce the slope of apitched roof. Sprockets are generally most suitable for use on widesteeply pitched roofs to:• enhance the roof profile by creating a feature.• to slow the velocity of rainwater running off the roof andprevent it over-shooting the ...

  • Page 443

    Roof Underlays ~ sometimes called sarking or roofing felt providesthe barrier to the entry of snow, wind and rain blown between thetiles or slates. It also prevents the entry of water from capillaryaction.Suitable Materials ~Bitumen fibre based felts † supplied in rolls 1 m wide and up to 25 ml...

  • Page 444

    Double Lap Tiles ~ these are the traditional tile covering for pitchedroofs and are available made from clay and concrete and are usuallycalled plain tiles. Plain tiles have a slight camber in their length to ensurethat the tail of the tile will bed and not ride on the tile below. There isalways ...

  • Page 445

    Hand made from extracted clay sub-strata. Sources of suitableclay in the UK are the brick making areas of Kent, Sussex andLeicestershire.Tiles are shaped in a timber frame or clamp before being kiln firedatabout1000°C.Earlyexamplesofthesetileshavebeenattributed to the Romans, but after they left...

  • Page 446

    Typical details (cold roof) ~timber battens underlay rafters ceiling joists insulation between and over joists vapour-checkplasterboardceiling (see Note 1)50 mm deep wall plate external wall with insulated cavity cavity insulation EAVES DETAIL 10 mm wide continuous ventilation gap fascia soffit b...

  • Page 447

    Note 1. If a cavity closer is also required to function as a cavitybarrier to prevent fire spread, it should provide at least 30minutes fire resistance, (B. Reg. A.D. B3 Section 6 [Vol. 1] and 9[Vol. 2]).Note 2. A breather membrane is an alternative to conventionalbituminous felt as an under-tili...

  • Page 448

    Typical detail (warm roof) ~Where a roof space is used for habitable space, insulation must beprovided within the roof slope. Insulation above the rafters (asshown) creates a `warm roof', eliminating the need for continuousventilation. Insulation placed between the rafters creates a `coldroof',wh...

  • Page 449

    Insulation in between rafters is an alternative to placing it above.The following details show two possibilities, where if requiredsupplementary insulation can be secured to the underside ofrafters.counter batteninsulation between raftersvapour control layerplasterboard inclined ceilingSealed War...

  • Page 450

    437Double Lap Tiling

  • Page 451

    438Double Lap Tiling

  • Page 452

    Single Lap Tiling ~ so called because the single lap of one tile overanother provides the weather tightness as opposed to the twolayers of tiles used in double lap tiling. Most of the single lap tilesproduced in clay and concrete have a tongue and groove jointalong their side edges and in some pa...

  • Page 453

    lap margin underside of deep profiles filled with filler piece or bedded in cm.mt. on eaves course of plain tiles margin = gauge =tile length — lap fascia ventilation gap soffit board cavity insulation external wall with thermal blockwork inner leaf 100 × 50 wall plate vapour checkplasterboard...

  • Page 454

    Slates ~ slate is a natural dense material which can be split into thinsheets and cut to form a small unit covering suitable for pitchedroofs in excess of 25° pitch. Slates are graded according to thicknessand texture, the thinnest being known as `Bests'. These are of 4 mmnominal thickness. Slat...

  • Page 455

    The UK has been supplied with its own slate resources fromquarries in Wales, Cornwall and Westermorland. Imported slate isalso available from Spain, Argentina and parts of the Far East.e.g. Countess slate, 510¾ 255 mm laid to a 30° pitch with 75 mmhead lap.Batten gauge = (slate length † lap)...

  • Page 456

    Traditional slate names and sizes (mm) †Empress650¾ 400Wide Viscountess460¾ 255Princess610¾ 355Viscountess460¾ 230Duchess610¾ 305Wide Ladies405¾ 255Small Duchess560¾ 305Broad Ladies405¾ 230Marchioness560¾ 280Ladies405¾ 205Wide Countess510¾ 305Wide Headers355¾ 305Countess510¾ 255Hea...

  • Page 457

    Roof hip examples †444Roof Slating --- Applications

  • Page 458

    Roof valley examples †Note: In swept valleys, cut and tapered slates are interleavedwith 1.25 mm lead soakers.445Roof Slating --- Applications

  • Page 459

    Materials † water reed (Norfolk reed), wheat straw (Spring orWinter), Winter being the most suitable. Wheat for thatch is oftenknown as wheat reed, long straw or Devon reed. Other thatchesinclude rye and oat straws, and sedge. Sedge is harvested everyfourth year to provide long growth, making i...

  • Page 460

    Flat Roofs ~ these roofs are very seldom flat with a pitch of 0°but are considered to be flat if the pitch does not exceed 10°. Theactual pitch chosen can be governed by the roof covering selectedand/or by the required rate of rainwater discharge off the roof. Asa general rule the minimum pitch...

  • Page 461

    Timber Roof Joists ~ the spacing and sizes of joists is related tothe loadings and span, actual dimensions for domestic loadings canbe taken direct from recommendations in Approved Document A orthey can be calculated as shown for timber beam designs. Struttingbetween joists should be used if the ...

  • Page 462

    Ref. BS 8217: Reinforced bitumen membranes for roofing. Code ofpractice.449Timber Flat Roofs---2

  • Page 463

    Conservation of Energy ~ this can be achieved in two ways:1 . Cold Deck † insulation is placed on the ceiling lining, betweenjoists. See page 448 for details. A metallized polyester linedplasterboard ceiling functions as a vapour control layer, witha minimum 50 mm air circulation space between ...

  • Page 464

    Built-up Roofing Felt ~ this consists of three layers of bitumenroofingfelttoBSEN13707,andshouldbelaidtotherecommendations of BS 8217. The layers of felt are bondedtogether with hot bitumen and should have staggered laps of50 mm minimum for side laps and 75 mm minimum for end laps † fortypical ...

  • Page 465

    Milled Lead Sheet ~ produced from refined lead to an initialthickness of about 125 mm. Thereafter it is rolled and cut to12.000 m lengths, 2.400 m wide into the following thicknesses andcategories:Other Dimensions ~ cut widths between 75 mm and 600 mm in coils.Density ~ approximately 11,325 kg/m3...

  • Page 466

    Thermal Movement ~ the coefficient of linear expansion for lead is0.0000297 (2.97¾ 10†6) for every degree Kelvin.Eg. If the exposure temperature range throughout a year is from†10°Cto35°C (45 K), then a 2.000 m length of sheet lead couldincrease by: 0.0000297¾ 45¾ 2 = 0.00267 m, or 2.67 ...

  • Page 467

    2 mm lead sheet50 mm highwood coredroll, 25 mmwide at base25 mm rebatefor lead nailedevery 100 mmanti-capillary groovesmooth surface deckingor decking plus underlayovercloak40 mm splashlapundercloak nailedevery 150 mm to topof rollTypical provision of wood cored rollsand drips † detail at junct...

  • Page 468

    Spacing of wood cored rolls and drips varies with the thicknessspecification of lead sheet. The following is a guide ~Typical flat roof plan (page 417)100 mm min.abutment upstandto wall withapron flashingwood coredrollsee previouspagedripvergefascia downstandinto gutterBABS EN 12588thickness (mm)...

  • Page 469

    A dormer is the framework for a vertical window constructed fromthe roof slope. It may be used as a feature, but is more likely asaneconomicalandpracticalmeansforaccessinglightandventilation to an attic room. Dormers are normally external withthe option of a flat or pitched roof. Frame constructi...

  • Page 470

    roofslopePitched optionsgable or hip endeavesalternative ceiling joist/tieridge boardtrimmed commonraftersalternative headtrimmer positionceiling joistshead trimmertrimming rafterinternal studdingbetween trimmingrafters and floor joistscorner postfloor joistssill trimmercheekpostscornerposthead b...

  • Page 471

    A graceful interruption to the routine of a pitched roof, derivedfrom thatched roofs where the thatch is swept over windowopenings. Other suitable coverings are timber shingles, plain tilesand small slates.Main roof pitch >†50°. Eyebrow pitch >†35°.Transition curve should be smooth wi...

  • Page 472

    Air carries water vapour, the amount increasing proportionallywith the air temperature. As the water vapour increases so doesthe pressure and this causes the vapour to migrate from warmerto cooler parts of a building. As the air temperature reduces, sodoes its ability to hold water and this manif...

  • Page 473

    Roof ventilation † provision of eaves ventilation alone shouldallow adequate air circulation in most situations. However, in someclimatic conditions and where the air movement is not directly atright angles to the building, moist air can be trapped in the roofapex. Therefore, supplementary ridg...

  • Page 474

    Refs.BuildingRegulations,ApprovedDocumentC†Sitepreparation and resistance to contaminants and moisture.Section 6 † Roofs.BS 5250: Code of practice for control of condensation inbuildings.BRE report † Thermal Insulation: avoiding risks (3rd. ed.).461Ventilation of Roof Spaces---3

  • Page 475

    Lateral Restraint † stability of gable walls and construction atthe eaves, plus integrity of the roof structure during excessivewindforces,requirescomplementaryrestraintandcontinuitythrough 30¾ 5 mm cross sectional area galvanised steel straps.Exceptions may occur if the roof:-1. exceeds 15° ...

  • Page 476

    Preservation~ref.BuildingRegulations:MaterialsandWorkmanship. Approved Document to support Regulation 7.Woodworm infestation of untreated structural timbers is common.However, the smaller woodborers such as the abundant Furniturebeetle are controllable. It is the threat of considerable damagepote...

  • Page 477

    Preservation ~ treatment of timber to prevent damage from HouseLonghorn beetle.In the areas specified (see previous page), all softwood used in roofstructures including ceiling joists and any other softwood fixingsshould be treated with insecticide prior to installation. Specificchemicals and pro...

  • Page 478

    Green roof ~ green with reference to the general appearance ofplant growths and for being environmentally acceptable. Part ofthe measures for constructing sustainable and ecologically friendlybuildings.Categories ~• Extensive ~ a relatively shallow soil base (typically 50 mm) andlightweight con...

  • Page 479

    Typical extensive roof build up ~grass/sedum soil filter layer or fleece drainage layer* waterproof membraneinsulation vapour control layer reinforced concrete roof structure * typically, expanded polystyrene with slots147 kg/m2 saturated weight x 9.81 = 1442 N/m2 or 1.44 kN/m2Typical intensive r...

  • Page 480

    Thermalinsulationofexternalelementsofconstructionismeasured in terms of thermal transmittance rate, otherwise knownastheU-value.Itistheamountofheatenergyinwattstransmitted through one square metre of construction for everyone degree Kelvin between external and internal air temperature,i.e. W/m2K....

  • Page 481

    Thermalresistances(R)areacombinationofthedifferentstructural, surface and air space components which make up anelement of construction. Typically:U=1Rso + R1 + R2 + Ra + R3 + R4 etc ... + Rsi(m2K=W)Where: Rso = Outside or external surface resistance.R1,R2, etc. = Thermal resistance of structural ...

  • Page 482

    Typical values in: m2K/WInternal surface resistances (Rsi):Walls † 0Á 123Floors or ceilings for upward heat flow † 0Á 104Floors or ceilings for downward heat flow † 0Á 148Roofs (flat or pitched) † 0Á 104External surface resistances (Rso):Sheltered † town buildings to 3 storeys.Norma...

  • Page 483

    Typical values †MaterialDensity(kg/m3)Conductivity ()(W/mK)WALLS:Boarding (hardwood)7000„1 8.. .. .. (softwood)5000„1 3Brick outer leaf1 7000„84.. .. inner leaf1 7000„62Calcium silicate board8750„1 7Ceramic tiles23001 „30Concrete24001 „93.. .. .. .. ..22001 „59.. .. .. .. ..2000...

  • Page 484

    Notes:1 . For purposes of calculating U-values, the effect of mortar inexternalbrickworkisusuallyignoredasthedensityandthermal properties of bricks and mortar are similar.2. Where butterfly wall ties are used at normal spacing in aninsulatedcavity<†75 mm,noadjustmentisrequiredtocalculations....

  • Page 485

    * Tables and charts † Insulation manufacturers' design guidesand technical papers (walls, roofs and ground floors).* Calculation using the Proportional Area Method (walls and roofs).* Calculation using the Combined Method † BS EN ISO 6946(walls and roofs).* Calculation using BS EN ISO 13370 (...

  • Page 486

    Variousapplicationstodifferentgroundfloorsituationsareconsidered in BS EN ISO 13370. The following is an example for asolid concrete slab in direct contact with the ground. The dataused is from the previous page.Floor sectionPerimeter = 18 m (exposed)Floor area = 20 m2 for 90 mm insulation = 0.03...

  • Page 487

    A standard block with mortar is 450¾ 225 mm = 101250 mm2A standard block format of 440¾ 215 mm= 94600 mm2The area of mortar per block=6650 mm2Proportional area of mortar =6650101250 ¾ 1001= 6„57%(0:066)Therefore the proportional area of blocks = 93„43%(0„934)Thermal resistances (R):Outer...

  • Page 488

    Combined Method (Wall)This method considers the upper and lower thermal resistance (R)limitsof anelementof structure.Theaverage of these isreciprocated to provide the U-value.Formula for upper and lower resistances =1Æ(Fx… Rx)Where: Fx = Fractional area of a sectionRx = Total thermal resistanc...

  • Page 489

    Notes:1 . The air space in the loft area is divided between pitched and ceilingcomponents, ie. Ra =0Á180 Ä 2= 0Á090 m2K/W.2. The U-value is calculated perpendicular to the insulation, therefore thepitched component resistance is adjusted by multiplying by the cosine ofthe pitch angle, ie. 0Á8...

  • Page 490

    Standard Assessment Procedure ~ the Approved Document to PartLoftheBuildingRegulationsemphasisestheimportanceofquantifying the energy costs of running homes. For this purpose ituses the Government's Standard Assessment Procedure (SAP). SAPhas a numerical scale of 1 to 100, although it can exceed ...

  • Page 491

    Domestic buildings (England and Wales) ~The area weighted average U-value for an element of constructiondepends on the individual U-values of all components and the areathey occupy within that element. E.g. The part of a wall with a metercupboard built in will have less resistance to thermal tran...

  • Page 492

    Further Quality Procedures (Structure) ~* Provisionofinsulationtobecontinuous.Gapsareunacceptableandifallowedtooccurwillinvalidatetheinsulation value by thermal bridging.* Junctions at elements of construction (wall/floor, wall/roof)to receive particular attention with regard to continuity ofinsu...

  • Page 493

    European Window Energy Rating Scheme (EWERS) ~ an alternativeto U-values for measuring the thermal efficiency of windows.U-values form part of the assessment, in addition to factors forsolar heat gain and air leakage. In the UK, testing and labelling ofwindowmanufacturer'sproductsispromotedbytheB...

  • Page 494

    The UK Government's Dept. of Energy and Climate Change (DECC)Standard Assessment Procedure (SAP) for energy rating dwellings,includes a facility to calculate carbon dioxide (CO2) emissions inkilograms or tonnes per year. The established carbon index methodallows for adjustment to dwelling floor a...

  • Page 495

    • Basisforimprovement~totalannualCO2emissionsarearound 150 million tonnes (MtC).• CO2 represents about 85% of all greenhouse gases producedbyburningfossilfuels(methane6%,nitrousoxide5%,industrial trace gases the remainder).• 25millionhomesproduceabout27%(41MtC)ofcarbonemissions, representin...

  • Page 496

    In new buildings and those subject to alterations, the objective isto optimise the use of fuel and power to minimise emission ofcarbon dioxide and other burnt fuel gases into the atmosphere.This applies principally to the installation of hot water, heating,lighting, ventilation and air conditioni...

  • Page 497

    Buildings Other Than Dwellings (England and Wales) ~Notes:• Fordisplaywindowsseparateconsiderationapplies.SeeSection 5 in A.D., L2A.• The poorest acceptable thermal transmittance values providesome flexibility for design, allowing a trade off against otherthermally beneficial features such as...

  • Page 498

    Thermal Insulation ~ this is required within the roof of all dwellingsin the UK. It is necessary to create a comfortable internalenvironment, to reduce the risk of condensation and to economisein fuel consumption costs.To satisfy these objectives, insulation may be placed between andover the ceil...

  • Page 499

    Thermal insulation to Walls ~ the minimum performance standardsfor exposed walls set out in Approved Document L to meet therequirements of Part L of the Building Regulations can be achievedin several ways (see pages 478 and 479). The usual methodsrequire careful specification, detail and construc...

  • Page 500

    Typical examples of contemporary construction practice thatachieve a thermal transmittance or U-value below 0„30 W/m2K~120 mm mineral wool cavity batts 100 mm lightweight concrete block inner leaf 13 mm lightweight plaster 102.5 mm external brick outer leaf 75 mm mineral wool cavity batts light...

  • Page 501

    ThermalorColdBridging~thisisheatlossandpossiblecondensation, occurring mainly around window and door openingsandatthejunctionbetweengroundfloorandwall.Otheropportunitiesforthermalbridgingoccurwhereuniformconstructionisinterruptedbyunspecifiedcomponents,e.g.occasional use of bricks and/or tile sli...

  • Page 502

    Asshownontheprecedingpage,continuityofinsulatedconstruction in the external envelope is necessary to preventthermal bridging. Nevertheless, some discontinuity is unavoidablewhere the pattern of construction has to change. For example,windowsanddoorshavesignificantlyhigherU-valuesthanelsewhere. He...

  • Page 503

    The possibility of a thermal or cold bridge occurring in a specific location canbe appraised by calculation. Alternatively, the calculations can be used todetermine how much insulation will be required to prevent a cold bridge. Thecomposite lintel of concrete and steel shown below will serve as a...

  • Page 504

    Air Infiltration ~ heating costs will increase if cold air is allowed topenetrateperipheralgapsandbreaksinthecontinuityofconstruction.Furthermore,heatenergywillescapethroughstructural breaks and the following are prime situations fortreatment:-1 . Loft hatch2. Services penetrating the structure3....

  • Page 505

    Main features of Approved Document (A.D.) M: Access to and useof buildings, and other associated guidance †* Site entrance or car parking space to building entrance to befirm and level. Building approach width 900 mm min. A gentleslope is acceptable with a gradient up to 1 in 20 and up to 1in 4...

  • Page 506

    Main features ~* Site entrance, or car parking space to building entrance to befirm and level, ie. maximum gradient 1 in 20 with a minimumcaraccesszoneof1200 mm.Rampedandeasysteppedapproaches are also acceptable.* Access to include tactile warnings, ie. profiled (blistered orribbed) pavings over ...

  • Page 507

    * Main access and internal fire doors that self-close should havea maximum operating force of 20 Newtons at the leadingedge. If this is not possible, a power operated door openingand closing system is required.* Corridorsandpassageways,minimumunobstructedwidth1200 mm. Internal lobbies as describe...

  • Page 508

    6 SUPERSTRUCTURE † 2REINFORCED CONCRETE SLABSREINFORCED CONCRETE FRAMED STRUCTURESSTRUCTURAL CONCRETE FIRE PROTECTIONFORMWORKPRECAST CONCRETE FRAMESPRESTRESSED CONCRETESTRUCTURAL STEELWORK ASSEMBLYSTRUCTURAL STEELWORK CONNECTIONSSTRUCTURAL FIRE PROTECTIONCOMPOSITE TIMBER BEAMSROOF SHEET COVERIN...

  • Page 509

    Simply Supported Slabs ~ these are slabs which rest on a bearingand for design purposes are not considered to be fixed to thesupport and are therefore, in theory, free to lift. In practicehowever they are restrained from unacceptable lifting by their ownself weight plus any loadings.Concrete Slab...

  • Page 510

    Reinforcement ~ generally in the form of steel bars which are usedto provide the tensile strength which plain concrete lacks. Thenumber, diameter, spacing, shape and type of bars to be used haveto be designed; a basic guide is shown on pages 501 and 502.Reinforcement is placed as near to the outs...

  • Page 511

    Construction ~ whatever method of construction is used theconstruction sequence will follow the same pattern-1. Assemble and erect formwork.2. Prepare and place reinforcement.3. Pour and compact or vibrate concrete.4. Strike and remove formwork in stages as curing proceeds.498Simply Supported RC ...

  • Page 512

    Profiled galvanised steel decking is a permanent formwork systemfor construction of composite floor slabs. The steel sheet hassurface indentations and deformities to effect a bond with theconcrete topping. The concrete will still require reinforcing withsteel rods or mesh, even though the metal s...

  • Page 513

    Beams ~ these are horizontal load bearing members which areclassified as either main beams which transmit floor and secondarybeam loads to the columns or secondary beams which transmitfloor loads to the main beams.Concrete being a material which has little tensile strength needs tobe reinforced t...

  • Page 514

    Mild Steel Reinforcement † located in areas where tension occursin a beam or slab. Concrete specification is normally 25 or 30 N/mm2 inthis situation.Note: Distribution or cross bars function as lateral reinforcementand supplement the units strength in tensile areas. They alsoprovideresistancet...

  • Page 515

    Guidance † simply supported slabs are capable of the followingloading relative to their thickness:Note: As arule of thumb, it is easy to remember that for generaluse (as above), thickness of slab equates to 1/24 span.* Imposed loading varies with application from 1„5 kN/m2 (153 kg/m2)for dome...

  • Page 516

    Bond Between Concrete and Steel † permissible stress for the bondbetween concrete and steel can be taken as one tenth of thecompressive concrete stress, plus 0„175 N/mm2*. Given the stresses inconcrete and steel, it is possible to calculate sufficient grip length.e.g. concrete working stress ...

  • Page 517

    Columns ~ these are the vertical load bearing members of thestructural frame which transmits the beam loads down to thefoundations. They are usually constructed in storey heights andtherefore the reinforcement must be lapped to provide structuralcontinuity.504In-situ RC Framed Structures -- Columns

  • Page 518

    With the exception of where bars are spliced ~BEAMSThe distance between any two parallel bars in the horizontalshould be not less than the greater of:* 25 mm* the bar diameter where they are equal* the diameter of the larger bar if they are unequal* 6 mm greater than the largest size of aggregate...

  • Page 519

    Typical RC Column Details ~Steel Reinforced Concrete † a modular ratio represents theamount of load that a square unit of steel can safely transmitrelative to that of concrete. A figure of 18 is normal, with somevariation depending on materials specification and quality.Area of concrete = 88,74...

  • Page 520

    Buckling or Bending Effect † the previous example assumed totalrigidity and made no allowance for column length and attachmentssuch as floor beams.The working stress unit for concrete may be taken as 0.8 timesthe maximum working stress of concrete where the effective lengthof column (see page 5...

  • Page 521

    Bar Coding ~ a convenient method for specifying and coordinatingthe prefabrication of steel reinforcement in the assembly area. It isalso useful on site, for checking deliveries and locating materialsrelativetoprojectrequirements.BSENISO3766providesguidance for a simplified coding system, such th...

  • Page 522

    Bar Schedule ~ this can be derived from the coding explained onthe previous page. Assuming 10 No. beams are required:-Bar coding ~Note: 9 is used for special or non-standard shapes1st character2nd character0 No bends0 Straight bars11 bend190° bends, standard radius, all bends towards samedirecti...

  • Page 523

    Material ~ Mild steel or high yield steel. Both contain about 99%iron, the remaining constituents are manganese, carbon, sulphurand phosphorus. The proportion of carbon determines the qualityand grade of steel; mild steel has 0„25% carbon, high yield steel0„40%. High yield steel may also be p...

  • Page 524

    Steel reinforcement mesh or fabric is produced in four differentformats for different applications:Standard sheet size ~ 4„8 m long¾ 2„4 m wide.Standard roll size ~ 48 and 72 m long¾ 2„4 m wide.Specification ~ format letter plus a reference number. This numberequates to the cross sectiona...

  • Page 525

    Cover to reinforcement in columns, beams, foundations, etc. isrequired for the following reasons:• To protect the steel against corrosion.• To provide sufficient bond or adhesion between steel and concrete.• To ensure sufficient protection of the steel in a fire (see Note).If the cover is i...

  • Page 526

    Typical examples using dense concrete of calcareous aggregates(excluding limestone) or siliceous aggregates, eg. flints, quartzitesand granites ~Column fully exposed ~35 mm min. concrete cover to reinforcement 300 mm min. each face, 120 minutes fire resistance 450 mm min. each face, 240 minutes f...

  • Page 527

    Formwork ~ concrete when first mixed is a fluid and therefore toform any concrete member the wet concrete must be placed in asuitable mould to retain its shape, size and position as it sets. It ispossible with some forms of concrete foundations to use the sidesof the excavation as the mould but i...

  • Page 528

    515Basic Formwork---Details

  • Page 529

    Beam Formwork ~ this is basically a three sided box supported andpropped in the correct position and to the desired level. The beamformwork sides have to retain the wet concrete in the requiredshape and be able to withstand the initial hydrostatic pressure ofthe wet concrete whereas the formwork ...

  • Page 530

    Column Formwork ~ this consists of a vertical mould of the desiredshape and size which has to retain the wet concrete and resist theinitial hydrostatic pressure caused by the wet concrete. To keepthe thickness of the formwork material to a minimum horizontalclamps or yokes are used at equal centr...

  • Page 531

    Column Yokes ~ these are obtainable as a metal yoke or clamp orthey can be purpose made from timber.Typical Examples ~518Formwork---Column Clamps and Yokes

  • Page 532

    Wall forms ~ conventionally made up of plywood sheeting thatmay be steel, plastic or wood faced for specific concrete finishes.Stability is provided by vertical studs and horizontal walingsretained in place by adjustable props. Base location is by a kickerof 50 of 75 mm height of width to suit th...

  • Page 533

    Formwork sides to concrete walls of modest height and load canbe positioned with long bolts or threaded dowel bars insertedthrough the walings on opposing sides. To keep the wall formsapart, tube spacers are placed over the bolts between the forms.For greater load applications, variations include...

  • Page 534

    Precast Concrete Frames ~ these frames are suitable for singlestorey and low rise applications, the former usually in the form ofportal frames which are normally studied separately. Precastconcrete frames provide the skeleton for the building and can beclad externally and finished internally by a...

  • Page 535

    Foundation Connections ~ the preferred method of connection is toset the column into a pocket cast into a reinforced concrete padfoundation and is suitable for light to medium loadings. Whereheavy column loadings are encountered it may be necessary to useasteelbaseplatesecuredtothereinforcedconcr...

  • Page 536

    Column to Column Connection ~ precast columns are usually castin one length and can be up to four storeys in height. They areeither reinforced with bar reinforcement or they are prestressedaccording to the loading conditions. If column to column arerequired they are usually made at floor levels a...

  • Page 537

    Beam to Column Connections ~ as with the column to columnconnections (see page 523) the main objective is to providestructural continuity at the junction. This is usually achieved byone of two basic methods:-1. Projecting bearing haunches cast onto the columns with aprojecting dowel or stud bolt ...

  • Page 538

    Principles ~ the well known properties of concrete are that it hashigh compressive strength and low tensile strength. The basicconcept of reinforced concrete is to include a designed amount ofsteel bars in a predetermined pattern to give the concrete areasonable amount of tensile strength. In pre...

  • Page 539

    Materials ~ concrete will shrink whilst curing and it can also suffersectional losses due to creep when subjected to pressure. Theamount of shrinkage and creep likely to occur can be controlled bydesigning the strength and workability of the concrete, highstrength and low workability giving the g...

  • Page 540

    Pre-tensioning~thismethodisusedmainlyinthefactoryproduction of precast concrete components such as lintels, floorunits and small beams. Many of these units are formed by the longline method where precision steel moulds up to 120„000 long areused with spacer or dividing plates to form the variou...

  • Page 541

    Post-tensioning ~ this method is usually employed where stressingis to be carried out on site after casting an in-situ component orwhere a series of precast concrete units are to be joined togetherto form the required member. It can also be used where curvedtendons are to be used to overcome nega...

  • Page 542

    Typical Post-tensioning Arrangement ~Anchorages ~ the formats for anchorages used in conjunction withpost-tensioned prestressed concreteworks depends mainly onwhether the tendons are to be stressed individually or as a group,but most systems use a form of split cone wedges or jaws actingagainst a...

  • Page 543

    ComparisonwithReinforcedConcrete~whencomparingprestressed concrete with conventional reinforced concrete themain advantages and disadvantages can be enumerated but in thefinal analysis each structure and/or component must be decided onits own merit.Main advantages:-1. Makesfulluseoftheinherentcom...

  • Page 544

    Ground Anchors ~ these are a particular application of post-tensioning prestressing techniques and can be used to form groundtie backs to cofferdams, retaining walls and basement walls. Theycan also be used as vertical tie downs to basement and similarslabs to prevent flotation during and after c...

  • Page 545

    Cold rolled steel sections are a lightweight alternative to therelativelyheavy,hotrolledsteelsectionsthathavebeentraditionally used in sub-framing situations, e.g. purlins, joists andsheeting rails. Cold rolled sections are generally only a fewmillimetres in wall thickness, saving on material and...

  • Page 546

    Structural Steelwork ~ standard section references:BS 4-1: Structural steel sections. Specification for hot rolled sections.BS EN 10056: Specification for structural steel equal and unequalangles.BS EN 10210: Hot finished structural hollow sections of non-alloyand fine grain steels.Typical Standa...

  • Page 547

    Compound Sections † these are produced by welding togetherstandard sections. Various profiles are possible, which can bedesigned specifically for extreme situations such as very high loadsandlongspans,wherestandardsectionsalonewouldbeinsufficient.Somepopularcombinationsofstandardsectionsinclude...

  • Page 548

    Open Web Beams † these are particularly suited to long spans withlight to moderate loading. The relative increase in depth will helpresist deflection and voids in the web will reduce structural deadload.Perforated Beam † a standard beam section with circular voids cutabout the neutral axis.Ca...

  • Page 549

    Lattices † these are an alternative type of open web beam, usingstandard steel sections to fabricate high depth to weight ratiounits capable of spans up to about 15 m. The range of possiblecomponents is extensive and some examples are shown below:Note: span potential for lattice beams is approx...

  • Page 550

    Structural Steelwork Connections ~ these are either workshop orsite connections according to where the fabrication takes place.Most site connections are bolted whereas workshop connectionsare very often carried out by welding. The design of structuralsteelwork members and their connections is the...

  • Page 551

    NB.Allholesforboltedconnectionsmustbemadefrombackmarking the outer surface of the section(s) involved. Foractual positions see structural steelwork manuals.538Structural Steelwork---Connections

  • Page 552

    Types ~Slab or bloom base.Gusset base.Steel grillage (see page 225).The type selected will depend on the load carried by the columnand the distribution area of the base plate. The cross sectionalarea of a UC concentrates the load into a relatively small part ofthe base plate. Therefore to resist ...

  • Page 553

    Welding is used to prefabricate the sub-assembly of steel framecomponents in the workshop, prior to delivery to site where theconvenience of bolted joints will be preferred.Oxygen and acetylene (oxy-acetylene) gas welding equipment maybe used to fuse together light steel sections, but otherwise i...

  • Page 554

    Bolts are the preferred method for site assembly of framed buildingcomponents, although rivets have been popular in the past and willbe found when working on existing buildings. Cold driven and `pop'rivets may be used for factory assembly of light steel frames suchas stud walling,but the traditio...

  • Page 555

    Fire Resistance of Structural Steelwork ~ although steel is a non-combustiblematerialwithnegligiblesurfacespreadofflameproperties it does not behave very well under fire conditions.During the initial stages of a fire the steel will actually gain instrength but this reduces to normal at a steel te...

  • Page 556

    Section Factors † these are criteria found in tabulated fireprotection data such as the Loss Prevention Certification Board'sStandards. These factors can be used to establish the minimumthickness or cover of protective material for structural sections.This interpretation is usually preferred by...

  • Page 557

    References: BS 4-1: Structural steel sections. Specification forhot-rolled sections.BS 449-2: Specification for the use of structural steelin building. Metric units.BS 5950-1: Structural use of steelwork in building. Codeof practice for design. Rolled and welded sections.BS EN 1993-1: Eurocode 3....

  • Page 558

    Simple beam design (Shear)From the previous example, the section profile is:-Maximum shear force normally occurs at the support points, i.e.near the end of the beam. Calculation is made of the averagestress value on the web sectional area.Using the example of 200 kN load distributed over the beam...

  • Page 559

    Simple beam design (Deflection)The deflection due to loading, other than the weight of thestructure, should not exceed 1/360 of the span.Theformulatodeterminetheextentofdeflectionvaries,depending on:-(a) Point loading(b) Uniformly distributed loadingwhere: W = load in kNL = span in cmE = Young's ...

  • Page 560

    Simple column designSteel columns or stanchions have a tendency to buckle or bendunder extreme loading. This can be attributed to:(a) length(b) cross sectional area(c) method of end fixing, and(d) the shape of section.(b) and (d) are incorporated into a geometric property of section,known as the ...

  • Page 561

    The tendency for a column to buckle depends on its slenderness asdetermined by the ratio of its effective length to the radius ofgyration about the weaker axis.Effective lengths of columns and struts in compression ~Ll = 0.7 LPosition and direction fixed is location at specific points bybeams or ...

  • Page 562

    Portal Frames ~ these can be defined as two dimensional rigidframes which have the basic characteristic of a rigid joint betweenthe column and the beam. The main objective of this form of designis to reduce the bending moment in the beam thus allowing theframe to act as one structural unit. The t...

  • Page 563

    550Portal Frames

  • Page 564

    551Portal Frames

  • Page 565

    552Portal Frames

  • Page 566

    Laminated Timber ~ sometimes called `Gluelam' and is the processof building upbeams,ribs,arches,portal framesandotherstructural units by gluing together layers of timber boards so thatthe direction of the grain of each board runs parallel with thelongitudinal axis of the member being fabricated.L...

  • Page 567

    Vertical Laminations ~ notoften used for structurallaminated timber membersand is unsatisfactoryfor curved members.Horizontal Laminations ~ most popular method for all types oflaminated timber members. The stress diagrams below show thatlaminates near the upper edge are subject to a compressive s...

  • Page 568

    Gluing ~ this should be carried out within 48 hours of the planingoperation to reduce the risk of the planed surfaces becomingcontaminated or case hardened (for suitable adhesives see page556). Just before gluing up the laminates they should be checkedfor `cupping.' The amount of cupping allowed ...

  • Page 569

    Adhesives ~ although timber laminates are carefully machined, theminimum of cupping permitted and efficient cramping methodsemployed it is not always possible to obtain really tight jointsbetween the laminates. One of the important properties of theadhesive is therefore that it should be gap fill...

  • Page 570

    Composite Beams ~ stock sizes of structural softwood havesectional limitations of about 225 mm and corresponding spanpotential in the region of 6 m. At this distance, even modestloadings could interpose with the maximum recommended deflectionof 0„003¾ span.Fabricated softwood box, lattice and ...

  • Page 571

    PSB ~ otherwise known as a parallam beam. Fabricated from longstrands of softwood timber bonded with a phenol-formaldehydeadhesive along the length of the beam to produce a structuralsection of greater strength than natural timber of equivalent section.Used for beams, lintels, structural framing ...

  • Page 572

    Composite Joist ~ a type of lattice frame, constructed from a pairof parallel and opposing stress graded softwood timber flanges,separated and jointed with a web of V shaped galvanised steelplate connectors. Manufacture is off-site in a factory qualitycontrolled situation. Here, joists can be mad...

  • Page 573

    Multi-storey Structures ~ these buildings are usually designed foroffice, hotel or residential use and contain the means of verticalcirculation in the form of stairs and lifts occupying up to 20% ofthe floor area. These means of circulation can be housed within acore inside the structure and this...

  • Page 574

    Typical Multi-storey Structures ~ the formats shown below aredesigned to provide lateral restraint against wind pressures.561Multi-storey Structures

  • Page 575

    Steel Roof Trusses ~ these are triangulated plane frames whichcarry purlins to which the roof coverings can be fixed. Steel isstronger than timber and will not spread fire over its surface andfor these reasons it is often preferred to timber for medium andlong span roofs. The rafters are restrain...

  • Page 576

    563SteelRoofTrussesupto12mSpan

  • Page 577

    Sheet Coverings ~ the basic functions of sheet coverings used inconjunction with steel roof trusses are to:-1. Provide resistance to penetration by the elements.2. Provide restraint to wind and snow loads.3. Provide a degree of thermal insulation of not less than thatset out in Part L of the Buil...

  • Page 578

    565Roof Sheet Coverings

  • Page 579

    566Roof Sheet Coverings

  • Page 580

    Double Skin, Energy Roof systems ~ apply to industrial andcommercial use buildings. In addition to new projects constructedto current thermal insulation standards, these systems can bespecifiedtoupgradeexistingsheetprofiledroofswithsuperimposedsupplementaryinsulation andprotective decking.Thermal...

  • Page 581

    Further typical details using profiled galvanised steel or aluminium,colour coated if required ~RIDGEcranked one-piece profiled ridge zed purlin ridge lining outer profiled sheetingVALLEY GUTTERcompressible profiled fillermineral fibrequilt insulationthermal break`plastic' spacerinner lining and ...

  • Page 582

    Long Span Roofs ~ these can be defined as those exceeding 12„000in span. They can be fabricated in steel, aluminium alloy, timber,reinforced concrete and prestressed concrete. Long span roofs canbe used for buildings such as factories. Large public halls andgymnasiums which require a large floo...

  • Page 583

    Pitched Trusses ~ these can be constructed with a symmetricaloutline (as shown on pages 562 to 563) or with an asymmetricaloutline (Northlight † see detail below). They are usually made fromstandard steel sections with shop welded or bolted connections,alternatively they can be fabricated using...

  • Page 584

    Monitor Roofs ~ these are basically a flat roof with raised glazed portions called monitors which forms aroof having a uniform distribution of daylight with no solar glare problems irrespective of orientation and aroof with easy access for maintenance. These roofs can be constructed with light lo...

  • Page 585

    Flat Top Girders ~ these are suitable for roof spans ranging from 15„000 to 45„000 and are basically lowpitched lattice beams used to carry purlins which support the roof coverings. One of the main advantagesof this form of roof is the reduction in roof volume. The usual materials employed in...

  • Page 586

    Bowstring Truss ~ a type of lattice truss formed with a curvedupper edge. Bows and strings may be formed in pairs of laminatedtimber sections that are separated by solid web timber sections ofstruts and ties.Spacing ~ 4.000 to 6.000 m apart depending on sizes of timbersections used and span.Purli...

  • Page 587

    Belfast Truss ~ established as one of the earliest forms ofbowstring truss for achieving an efficient and economical roofconstruction over large spans. It was first used in the latter partof the 19th century and early part of the 20th century forindustrial and agricultural buildings in response t...

  • Page 588

    Bowed Lattice Truss Details ~Bowstring ~steel or softwood fishplate (x2)laminated bow (x2)bracket or blockstrutbowstiessteel heelplatebolt and splitring connectionlaminatedtie (x2)centre tiepackingbetween bowsBelfast ~purlinbows (2)strings (2)plywood gussetpackingsteelanglelattice bracingsheetdec...

  • Page 589

    Connections ~ nails, screws and bolts have their limitations whenused to join structural timber members. The low efficiency of jointsmade with a rigid bar such as a bolt is caused by the usual lowshear strength of timber parallel to the grain and the non-uniformdistribution of bearing stress alon...

  • Page 590

    Space Deck ~ this is a structural roofing system based on a simplerepetitive pyramidal unit to give large clear spans of up to 22„000for single spanning designs and up to 33„000 for two way spanningdesigns. The steel units are easily transported to site beforeassembly into beams and the compl...

  • Page 591

    Space Frames ~ these are roofing systems which consist of a seriesofconnectorswhichjoinstogetherthechordsandbracingmembers of the system. Single or double layer grids are possible,the former usually employed in connection with small domes orcurved roofs. Space frames are similar in concept to spa...

  • Page 592

    Shell Roofs ~ these can be defined as a structural curved skincovering a given plan shape and area where the forces in the shellor membrane are compressive and in the restraining edge beamsare tensile. The usual materials employed in shell roof constructionare in-situ reinforced concrete and timb...

  • Page 593

    Barrel Vaults ~ these are single curvature shells which areessentially a cut cylinder which must be restrained at both ends toovercome the tendency to flatten. A barrel vault acts as a beamwhose span is equal to the length of the roof. Long span barrelvaults are those whose span is longer than it...

  • Page 594

    NB. ribs not connected to support columns will set up extrastresses within the shell roof therefore extra reinforcement will berequired at the stiffening rib or beam positions.581Shell Roof Construction

  • Page 595

    Other Forms of Barrel Vault ~ by cutting intersecting and placingat different levels the basic barrel vault roof can be formed into agroin or northlight barrel vault roof:-Conoids ~ these are double curvative shell roofs which can beconsidered as an alternative to barrel vaults. Spans up to 12„...

  • Page 596

    Hyperbolic Paraboloids ~ the true hyperbolic paraboloid shell roofshape is generated by moving a vertical parabola (the generator)over another vertical parabola (the directrix) set at right anglestothemovingparabola.Thisformsasaddleshapewherehorizontal sections taken through the roof are hyperbol...

  • Page 597

    Typical Straight Line Limited Hyperbolic Paraboloid Formats ~584Shell Roof Construction

  • Page 598

    ConcreteHyperbolicParaboloidShellRoofs~thesecanbeconstructed in reinforced concrete (characteristic strength 25 or30 N/mm2) with a minimum shell thickness of 50 mm with diagonalspans up to 35„000. These shells are cast over a timber form inthe shape of the required hyperbolic paraboloid format....

  • Page 599

    586Shell Roof Construction

  • Page 600

    A form of stressed skin reinforced concrete construction alsoknown as folded plate construction. The concept is to profile aflat slab into folds so that the structure behaves as a series ofbeams spanning parallel with the profile.Optimum depth to span ratio is between 1 : 10 to 1 : 15, or a depth...

  • Page 601

    MembraneStructurePrinciples~aformoftensionedcablestructural support system with a covering of stretched fabric. Inprinciple and origin, this compares to a tent with poles ascompression members secured to the ground. The fabric membraneis attached to peripheral stressing cables suspended in a cate...

  • Page 602

    Simple support structure as viewed from the underside ~vertical compression member stressed fabric reinforced gussets peripheral support or ties tensioned fabric support cables tensioned horizontalcables securedcentrally to avertical supportplateFabric~hastheadvantagesofrequiringminimalsupport,op...

  • Page 603

    Rooflights~theusefulpenetrationof daylightthroughthewindows in external walls of buildings is from 6„000 to 9„000depending on the height and size of the window. In buildings withspans over 18„000 side wall daylighting needs to be supplementedby artificial lighting or in the case of top floo...

  • Page 604

    591Rooflights

  • Page 605

    Lantern Lights ~ these are a form of rooflight used in conjuctionwith flat roofs. They consist of glazed vertical sides and fullyglazed pitched roof which is usually hipped at both ends. Part ofthe glazed upstand sides is usually formed as an opening light oralternativelyglazedwithlouvrestoprovid...

  • Page 606

    Dome,PyramidandSimilarRooflights~theseareusedinconjuction with flat roofs and may be framed or unframed. Theglazing can be of glass or plastics such as polycarbonate, acrylic,PVC and glass fibre reinforced polyester resin (grp). The wholecomponent is fixed to a kerb and may have a raising piececo...

  • Page 607

    Non-load Bearing Brick Panel Walls ~ these are used in conjunctionwith framed structures as an infill between the beams and columns.They are constructed in the same manner as ordinary brick wallswith the openings being formed by traditional methods.Basic Requirements ~1. To be adequately supporte...

  • Page 608

    reinforced concretecolumnNote: Standard cavitywall insulated asrequiredreinforced concreteperimeter beamdovetail channelsupport railset in concrete6 mm steel anglebracket, min. penetration intobrickworkgalvanised steelfish-tail tiesliding brick anchor ~(ties fit loosely overguide)brickworkmovemen...

  • Page 609

    Infill Panel Walls ~ these can be used between the framing membersof a building to provide the cladding and division between theinternal and external environments and are distinct from claddingsand facing:-Functional Requirements ~ all forms of infill panel should bedesignedandconstructedtofulfil...

  • Page 610

    Brick Infill Panels ~ these can be constructed in a solid or cavityformat, the latter usually having an inner skin of blockwork toincrease the thermal insulation properties of the panel. All thefundamental construction processes and detail of solid and cavitywalls (bonding, lintels over openings,...

  • Page 611

    Lightweight Infill Panels ~ these can be constructed from a widevariety or combination of materials such as timber, metals andplastics into which single or double glazing can be fitted. If solidpanels are to be used below a transom they are usually of acomposite or sandwich construction to provid...

  • Page 612

    LightweightInfillPanels~thesecanbefixedbetweenthestructural horizontal and vertical members of the frame or fixed tothe face of either the columns or beams to give a grid, horizontalor vertical emphasis to the fac¸ade thus †599Infill Panel Walls

  • Page 613

    Overcladding~asuperficialtreatment,appliedeitherasacomponent of new construction work, or as a fac¸ade and insulationenhancement to existing structures. The outer weather resistantdecorative panelling is `loose fit' in concept, which is easilyreplaced to suit changing tastes, new materials and c...

  • Page 614

    Glazed fac¸ades have been associated with hi-tech architecture sincethe 1970s. The increasing use of this type of cladding is largely dueto developments in toughened glass and improved qualities ofelastomeric silicone sealants. The properties of the latter mustincorporate a resilience to varying...

  • Page 615

    Structural glazing is otherwise known as frameless glazing. It is asystem of toughened glass cladding without the visual impact ofsurface fixings and supporting components. Unlike curtain walling,the self-weight of the glass and wind loads are carried by the glassitself and transferred to a subsi...

  • Page 616

    Curtain Walling ~ this is a form of lightweight non-load bearing externalcladding which forms a complete envelope or sheath around thestructural frame. In low rise structures the curtain wall framing couldbe of timber or patent glazing but in the usual high rise context, box orsolid members of st...

  • Page 617

    604Curtain Walling

  • Page 618

    Fixing Curtain Walling to the Structure ~ in curtain walling systemsit is the main vertical component or mullion which carries the loadsand transfers them to the structural frame at every or alternatefloor levels depending on the spanning ability of the mullion. Ateach fixing point the load must ...

  • Page 619

    Re-cladding existing framed buildings has become an economicalalternative to complete demolition and re-building. This may bejustified when a building has a change of use or it is in need of animage upgrade. Current energy conservation measures can also beachieved by the re-dressing of older buil...

  • Page 620

    Load bearing Concrete Panels ~ this form of construction usesstorey height load bearing pre-cast reinforced concrete perimeterpanels. The width and depth of the panels is governed by theload(s) to be carried, the height and exposure of the building.Panels can be plain or fenestrated providing the...

  • Page 621

    Concrete Cladding Panels ~ these are usually of reinforced precastconcrete to an undersill or storey height format, the former beingsometimes called apron panels. All precast concrete cladding panelsshould be designed and installed to fulfil the following functions:-1. Self supporting between fra...

  • Page 622

    Storey Height Cladding Panels ~ these are designed to spanvertically from beam to beam and can be fenestrated if required.Levelling is usually carried out by wedging and packing from floorlevel before being fixed by bolts or grouted dowels.Typical Details ~609Concrete Cladding--Storey Height

  • Page 623

    Single-Stage ~ the application of a compressible filling materialand a weatherproofing sealant between adjacent cladding panels.This may be adequate for relatively small areas and whereexposure to thermal or structural movement is limited. Elsewhere,in order to accommodate extremes of thermal mov...

  • Page 624

    baffleTypical weathering detail ~vertical dpcsealantstepped flashingWherethehorizontallappedjointbetweenupperandlowercladding panels coincides with the vertical open drained joint, astepped apron flashing is required to weather the intersection.Lead is the natural choice for this, but reinforced ...

  • Page 625

    Gasket ~ an alternative to using mastic or sealant to close thegap between two cladding panels. They are used specifically wheremovementsorjointwidthsaregreaterthancouldbeaccommodated by sealants. For this purpose a gasket is defined inBS 6093 as, `flexible, generally elastic, preformed material ...

  • Page 626

    Non-structural gasket types (shown plan view) ~HOLLOW/TUBULAR (cast into concrete during manufacture)SOLID DOUBLE SPLAY (fitted on site during assembly)pcc cladding panelsrecess in pcc panelExternal faceSOLID CRUCIFORMshoulder to tapered recessdrainage zonevertical recessGaskets have other applic...

  • Page 627

    Concrete Surface Finishes ~ it is not easy to produce a concretesurfacewithasmoothfinishofuniformcolourdirectfromthe mould or formwork since the colour of the concrete can beaffected by the cement and fine aggregate used. The concretesurface texture can be affected by the aggregate grading, cemen...

  • Page 628

    Cast-on Finishes ~ these finishes include split blocks, bricks, stone,tiles and mosaic. Cast-on finishes to the upper surface of ahorizontal casting are not recommended although such finishescould be bedded onto the fresh concrete. Lower face treatment isby laying the materials with sealed or gro...

  • Page 629

    Discolouration ~ manifests as a patchy surface finish. It is causedwhere there are differences in hydration or moisture loss during theconcreteset,duetoconcentrationsofcementorwhereaggregatesbecomesegregated.Bothofthesewillproducemoisture content differences at the surface. Areas with a darkersur...

  • Page 630

    7 INTERNAL CONSTRUCTIONAND FINISHESINTERNAL ELEMENTSINTERNAL WALLSCONSTRUCTION JOINTSPARTITIONS AND TIMBER STRUT DESIGNPLASTERS, PLASTERING AND PLASTERBOARDDRY LINING TECHNIQUESWALL TILINGDOMESTIC FLOORS AND FINISHESLARGE CAST IN-SITU GROUND FLOORSCONCRETE FLOOR SCREEDSTIMBER SUSPENDED FLOORSTIMB...

  • Page 631

    NB. roof coverings, roof insulation and guttering not shownNB. all work below dpc level is classed as substructure618Internal Elements

  • Page 632

    Internal Walls ~ their primary function is to act as a verticaldivider of floor space and in so doing form a storey heightenclosing element.619Internal Walls---Functions

  • Page 633

    Internal Walls ~ there are two basic design concepts for internalwalls those which accept and transmit structural loads to thefoundations are called Load Bearing Walls and those which supportonly their own self-weight and do not accept any structural loadsare called Non-load Bearing Walls or Part...

  • Page 634

    Internal Brick Walls ~ these can be load bearing or non-loadbearing (see previous page) and for most two storey buildings arebuilt in half brick thickness in stretcher bond.621Internal Brick Walls

  • Page 635

    Internal Block Walls ~ these can be load bearing or non-loadbearing (see page 620) the thickness and type of block to be usedwill depend upon the loadings it has to carry.622Internal Block Walls

  • Page 636

    Internal Walls ~ an alternative to brick and block bonding shownon the preceding two pages is application of wall profiles. Theseare quick and simple to install, provide adequate lateral stability,sufficient movement flexibility and will overcome the problem ofthermal bridging where a brick parti...

  • Page 637

    Movement or Construction Joints ~ provide an alternative to tiesormeshreinforcementinmasonrybedjoints.Evenwithreinforcement, lightweight concrete block walls are renowned forproducingunsightlyandpossiblyunstableshrinkagecracks.Galvanised or stainless steel formers and ties are built in at amaximu...

  • Page 638

    Location ~ specifically in positions of high stress.Reinforcement ~ expanded metal or wire mesh (see page 328).Mortar Cover ~ 13 mm minimum thickness, 25 mm to external faces.Openings~600 mm minimum door opening blockwork wall bed joint reinforcementlintelConcentrated Load ~padstone load bearing ...

  • Page 639

    Typical examples ~Solid brickworkT = thicknessNote: For practical reasons a standard one-brick dimension is givenfor 240 minutes fire resistance. Theoretically a clay brick wall canbe 170 mm and a concrete or sand/lime brick wall 200 mm, finishesexcluded.Solid concrete blocks of lightweight aggre...

  • Page 640

    Party Wall ~ a wall separating different owners buildings, ie. a wallthatstandsastridetheboundarylinebetweenpropertyofdifferent ownerships. It may also be solely on one owner's land butused to separate two buildings.ridge eaves upper floor boundary lineground floor party wall between dwellings fu...

  • Page 641

    Requirements for fire and sound resisting construction ~Typical masonry construction ~cavity stopped with a non-combustible mineral wool closer unless cavity is fully filled with mineral wool insulationexternal cavity wall Plan view solid or cavity construction of separating wall vertical dpcTypi...

  • Page 642

    Internal Partitions ~ these are vertical dividers which are used toseparatetheinternalspaceofabuildingintoroomsandcirculation areas such as corridors. Partitions which give supportto a floor or roof are classified as load bearing whereas thosewhich give no such support are called non-load bearing...

  • Page 643

    Timber Stud Partitions ~ these are non-load bearing internaldividing walls which are easy to construct, lightweight, adaptableand can be clad and infilled with various materials to give differentfinishes and properties. The timber studs should be of prepared orplaned material to ensure that the w...

  • Page 644

    Although generally non-load bearing, timber stud partitions maycarry some of the load from the floor and roof structure. In thesesituations the vertical studs are considered struts.Example ~ using the stud frame dimensions shown on the previouspage, with each stud (strut) supporting a 5 kN load.2...

  • Page 645

    Stud Partitions ~ these non-load bearing partitions consist of aframework of vertical studs to which the facing material can beattached. The void between the studs created by the two facescan be infilled to meet specific design needs. The traditionalmaterial for stud partitions is timber (see Tim...

  • Page 646

    Plasterboard lining to stud framed partition walls satisfies theBuilding Regulations, Approved Document B † Fire safety, as amaterial of ``limited combustibility'' with a Class O rating forsurface spread of flame (Class O is better than Classes 1 to 4 asdetermined by BS 476-7). The plasterboard...

  • Page 647

    Partitions ~ these can be defined as vertical internal space dividersandareusuallynon-loadbearing.Theycanbepermanent,constructed of materials such as bricks or blocks or they can bedemountable constructed using lightweight materials and capableof being taken down and moved to a new location incur...

  • Page 648

    Demountable Partitions ~ it can be argued that all internal non-load bearing partitions are demountable and therefore the majorproblem is the amount of demountability required in the context ofease of moving and the possible frequency anticipated. The rangeof partitions available is very wide inc...

  • Page 649

    Plaster ~ this is a wet mixed material applied to internal walls as afinish to fill in any irregularities in the wall surface and to providea smooth continuous surface suitable for direct decoration. Theplaster finish also needs to have a good resistance to impactdamage. The material used to fulf...

  • Page 650

    Internal Wall Finishes ~ these can be classified as wet or dry. Thetraditional wet finish is plaster which is mixed and applied to thewall in layers to achieve a smooth and durable finish suitable fordecorative treatments such as paint and wallpaper.Most plasters are supplied in 25 kg paper sacks...

  • Page 651

    Background ~ ideally level and of consistent material. If there areirregularities, three applications may be required; render (ct. andsand) 10†12 mm, undercoat plaster 6†8 mm and finish plaster 2 mm.Difficult backgrounds such as steel or glazed surfaces require aPVA bonding agent or a cement ...

  • Page 652

    Plasterboard ~ a board material comprising two outer layers oflining paper with gypsum plaster between † two edge profiles aregenerally available:-Tapered Edge † a flush seamless surface is obtained by filling thejoint with a special filling plaster, applying a joint tape overthe filling and ...

  • Page 653

    Dry Linings ~ an alternative to wet finishing internal wall surfaceswith render and plaster. Dry lining materials can be plasterboard,insulating fibre board, hardboard, timber boards, and plywood,all of which can be supplied with a permanent finish or they canbe supplied to accept an applied fini...

  • Page 654

    641Dry Lining Techniques

  • Page 655

    Plasterboard Types ~ to BS EN 520: Gypsum plasterboards.Definitions, requirements and test methods.BS PLASTERBOARDS:~1. Wallboard † ivory faced for taping, jointing and direct decoration; greyfaced for finishing plaster or wall adhesion with plaster dabs. Generalapplications, i.e. internal wall...

  • Page 656

    Fixing ~ the detail below shows board fixing with nails or screws totimber battens. This is an alternative to using plaster dabs andpads shown on page 639.Typical fixing ~battenspacing (c/c)block orbrickwork background38 19 mm softwoodbattens nailed or screwedto background at450 mm spacing9.5 mm...

  • Page 657

    Jointing ~ boards should not directly abut, instead a gap of 3 to5 mm should be provided between adjacent boards for plaster fillingandjointreinforcementtape.Theillustrationsshowvariousapplications.screw ornail fixinggap fillertaperededgeboardfinishtapefinishjoint fillerjoint fillerplaster skimfi...

  • Page 658

    Glazed Wall Tiles ~ internal glazed wall tiles are usually made tothevariousspecificationsunderBSEN14411:Ceramictiles.Definitions, classification, characteristics and marking.Internal Glazed Wall Tiles ~ the body of the tile can be made fromball-clay, china clay, china stone, flint and limestone....

  • Page 659

    Bedding of Internal Wall Tiles ~ generally glazed internal wall tilesare considered to be inert in the context of moisture and thermalmovement, therefore if movement of the applied wall tile finish isto be avoided attention must be given to the background and themethod of fixing the tiles.Backgro...

  • Page 660

    Primary Functions ~1. Provide a level surface with sufficient strength to support theimposed loads of people and furniture.2. Exclude the passage of water and water vapour to the interior of thebuilding.3. Provide resistance to unacceptable heat loss through the floor.4. Provide the correct type ...

  • Page 661

    This drawing should be read in conjunction with page 215 †Foundation Beds.A domestic solid ground floor consists of three components:-1. Hardcore † a suitable filling material to make up the top soilremoval and reduced level excavations. It should have a topsurface which can be rolled out to ...

  • Page 662

    Suspended Timber Ground Floors ~ these need to have a wellventilated space beneath the floor construction to prevent themoisture content of the timber rising above an unacceptable level(i.e. not more than 20%) which would create the conditions forpossible fungal attack.649Domestic Suspended Timbe...

  • Page 663

    Precast Concrete Floors ~ these have been successfully adaptedfrom commercial building practice (see pages 673 and 674), as aneconomic alternative construction technique for suspended timberand solid concrete domestic ground (and upper) floors. See alsopage 352 for special situations.Typical Deta...

  • Page 664

    Precast Reinforced Concrete Beam and Expanded Polystyrene(EPS) Block Floors ~ these have evolved from the principles ofbeam and block floor systems as shown on the preceding page.The light weight and easy to cut properties of the blocks providefor speed and simplicity in construction. Exceptional...

  • Page 665

    Floor Finishes ~ these are usually applied to a structural base butmay form part of the floor structure as in the case of floorboards. Most finishes are chosen to fulfil a particular functionsuch as:-1 . Appearance † chosen mainly for their aesthetic appeal oreffect but should however have reas...

  • Page 666

    Tongue and Groove Boarding ~preparedfromsoftwoodstothe recommendations of BS 1297.Boards are laid at right angles tothe joists and are fixed with 2 No.65 mm long cut floor brads perjoists. The ends of board lengthsare butt jointed on the centre lineof the supporting joist.Maximum board spans are:...

  • Page 667

    Large Cast-In-situ Ground Floors ~ these are floors designed tocarry medium to heavy loadings such as those used in factories,warehouses, shops, garages and similar buildings. Their design andconstruction is similar to that used for small roads (see pages 132to 134). Floors of this type are usual...

  • Page 668

    Vacuum Dewatering ~ if the specification calls for a power floatsurface finish vacuum dewatering could be used to shorten the timedelay between tamping the concrete and power floating thesurface. This method is suitable for slabs up to 300 mm thick. Thevacuum should be applied for approximately 3...

  • Page 669

    Concrete Floor Screeds ~ these are used to give a concrete floora finish suitable to receive the floor finish or covering specified. Itshould be noted that it is not always necessary or desirable toapply a floor screed to receive a floor covering, techniques areavailable to enable the concrete fl...

  • Page 670

    Separate Screeds †screed is laid onto the concretefloor slab after it has cured.The floor surface must be cleanand rough enough to ensure anadequate bond unless the floorsurface is prepared by applyinga suitable bonding agent or bybrushing with a cement/watergroutofathickcreamlikeconsistency ju...

  • Page 671

    Primary Functions ~1 . Provide a level surface with sufficient strength to supportthe imposed loads of people and furniture plus the dead loadsof flooring and ceiling.2. Reduce heat loss from lower floor as required.3. Provide required degree of sound insulation.4. Provide required degree of fire...

  • Page 672

    Strutting ~ used in timber suspendedfloors to restrict themovements due to twisting and vibration which could damageceiling finishes. Strutting should be included if the span of the floorjoists exceeds 2„5 m and is positioned on the centre line of thespan. Max. floor span ~ 6 m measured centre ...

  • Page 673

    Lateral Restraint ~ external, compartment (fire), separating (party)and internal loadbearing walls must have horizontal support fromadjacent floors, to restrict movement. Exceptions occur when thewall is less than 3 m long.Methods:1 . 90 mm end bearing of floor joists, spaced not more than 1„2 ...

  • Page 674

    Wall Stability † at right angles to floor and ceiling joists this isachieved by building the joists into masonry support walls orlocating them on approved joist hangers.Walls parallel to joists are stabilised by lateral restraint straps.Buildings constructed before current stability requirement...

  • Page 675

    Trimming Members ~ these are the edge members of an opening ina floor and are the same depth as common joists but are usually25 mm wider.662Timber Suspended Upper Floors

  • Page 676

    Typical spans and loading for floor joists of general structuralgrade †Dead weight of flooring andceiling, excluding the self weight of the joists (kg/m2)< 2525†5050†125Spacing of joists (mm)400450600400450600400450600Sawn size(mm¾ mm)Maximum clear span (m)38¾ 751.221.090.831.141.030.7...

  • Page 677

    Joist and Beam Sizing ~ design tables and formulae have limitations,therefore where loading, span and/or conventional joist spacings areexceeded, calculations are required. BS 5268: Structural Use OfTimber and BS EN 338: Structural Timber † Strength Classes, are bothuseful resource material for...

  • Page 678

    Joist and Beam Sizing ~ calculating overall dimensions alone isinsufficient, checks should also be made to satisfy: resistance todeflection, adequate safe bearing and resistance to shear.Deflection † should be minimal to prevent damage to plasteredceilings.Anallowanceofupto0„003¾ spanisnorma...

  • Page 679

    Typical situations ~notched joist over wallplatenotched joist to steel beamRSJ or UBh = heightabove notchwallplated = depthof joisth = heightclear ofnotchesIt is necessary to ensure enough timber above and/or below anotch to resist horizontal shear or shear parallel to the grain.To check whether ...

  • Page 680

    For fire protection, floors are categorised depending on theirheight relative to adjacent ground ~Tests for fire resistance relate to load bearing capacity, integrityand insulation as determined by BS 476 † 21: Fire tests on buildingmaterials and structures. Methods for determination of the fir...

  • Page 681

    ReinforcedConcreteSuspendedFloors~asimplereinforcedconcrete flat slab cast to act as a suspended floor is not usuallyeconomical for spans over 5„000. To overcome this problem beamscan be incorporated into the design to span in one or twodirections.Suchbeamsusuallyspanbetweencolumnswhichtransfer...

  • Page 682

    Ribbed Floors ~ to reduce the overall depth of a traditional castin-situ reinforced concrete beam and slab suspended floor a ribbedfloor could be used. The basic concept is to replace the widespaced deep beams with narrow spaced shallow beams or ribswhich will carry only a small amount of slab lo...

  • Page 683

    Ribbed Floors † these have greater span and load potential perunit weight than flat slab construction. This benefits a considerablereduction in dead load, to provide cost economies in other super-structural elements and foundations. The regular pattern of voidscreated with waffle moulds produce...

  • Page 684

    Hollow Pot Floors ~ these are in essence a ribbed floor withpermanent formwork in the form of hollow clay or concrete pots.The main advantage of this type of cast in-situ floor is that it hasa flat soffit which is suitable for the direct application of a plasterfinish or an attached dry lining. T...

  • Page 685

    Soffit and Beam Fixings ~ concrete suspended floors can bedesigned to carry loads other than the direct upper surfaceloadings. Services can be housed within the voids created by thebeams or ribs and suspended or attached ceilings can be supportedby the floor. Services which run at right angles to...

  • Page 686

    Precast Concrete Floors ~ these are available in several basicformats and provide an alternative form of floor construction tosuspended timber floors and in-situ reinforced concrete suspendedfloors. The main advantages of precast concrete floors are:-1.Elimination of the need for formwork except ...

  • Page 687

    674Precast Concrete Floors

  • Page 688

    675Precast Concrete Floors

  • Page 689

    Steel fabricated beams can be used as an integral means ofsupport for precast concrete floors. These are an overall depthand space saving alternative compared to down-stand reinforcedconcrete beams or masonry walls. Only the lower steel flange ofthe steel beam is exposed.To attain sufficient stre...

  • Page 690

    A standard manufactured steel beam with similar applications tothe plated UC shown on the previous page. This purpose madealternative is used with lightweight flooring units, such as precastconcrete hollow core slabs and metal section decking of the typeshown on page 499.Standard production seria...

  • Page 691

    Raised Flooring ~ developed in response to the high-tech boom ofthe 1970s. It has proved expedient in accommodating computer andcommunications cabling as well as numerous other establishedservices. The system is a combination of adjustable floor pedestals,supporting a variety of decking materials...

  • Page 692

    Sound Insulation ~ sound can be defined as vibrations of air which areregistered by the human ear. All sounds are produced by a vibrating objectwhich causes tiny particles of air around it to move in unison. These displacedair particles collide with adjacent air particles setting them in motion a...

  • Page 693

    The Approved Document to Building Regulation E2 provides forinternal walls and floors located between a bedroom or a roomcontaining a WC and other rooms to have a reasonable resistanceto airborne sound. Impact sound can be improved by provision of acarpet.Typical details ~75 mm min. timber frame4...

  • Page 694

    Separating Walls ~ types:-1. Solid masonry2. Cavity masonry3. Masonry between isolating panels4. Timber frameMaterialADensityof A[Kg/m3]Finish BCombined mass A +B (Kg/m2)ThicknessC [mm]CoursingD [mm]brickwork161013 mmlwt. pl.37521575.. .... ..12„5 mmpl. brd... .... .... ..Concreteblock184013 mm...

  • Page 695

    Panel materials † B(i) Plasterboard with cellular core plus plaster finish, mass 18 kg/m2.All joints taped. Fixed floor and ceiling only.(ii) 2 No. plasterboard sheets, 12„5 mm each, with joints staggered.Frame support or 30 mm overall thickness.Absorbent material † quilting of unfaced mine...

  • Page 696

    Separating Floors ~ types:-1. Concrete with soft covering2. Concrete with floating layer3. Timber with floating layerResilient layers:(a) 25 mm paper faced mineral fibre, density 36 kg/m3.Timber floor † paper faced underside.Screeded floor † paper faced upper side to prevent screed entering l...

  • Page 697

    Type 3. Airborne resistance varies depending on floor construction,absorbency of materials, extent of pugging and partly onthe floating layer. Impact resistance depends mainly on theresilient layer separating floating from structure.Note: Minimum mass per unit area = 25 kg/m2Floating layer: 18 mm...

  • Page 698

    Primary Functions ~1. Provide a means of circulation between floor levels.2. Establish a safe means of travel between floor levels.3. Provide an easy means of travel between floor levels.4. Provide a means of conveying fittings and furniture betweenfloor levels.685Domestic Stairs

  • Page 699

    All dimensions quoted are the minimum required for domestic stairsexclusive to one dwelling as given in Approved Document K unlessstated otherwise.* AD K does not give a minimum dimension for stair width. See alsopage 690.686Domestic Straight Flight Stairs---Critical Dimensions

  • Page 700

    687Straight Flight Timber Stair Details

  • Page 701

    Projecting bottom steps are usually included to enable the outerstring to be securely jointed to the back face of the newel postand to provide an easy line of travel when ascending or descendingat the foot of the stairs.688Straight Flight Timber Stair Details

  • Page 702

    689Straight Flight Timber Stair Details

  • Page 703

    Open Riser Timber Stairs ~ these are timber stairs constructed tothe same basic principles as standard timber stairs excluding theuse of a riser. They have no real advantage over traditional stairsexcept for the generally accepted aesthetic appeal of elegance.Like the traditional timber stairs th...

  • Page 704

    Design and Construction ~ because of the legal requirement of nothaving a gap between any two consecutive treads through which a100 mm diameter sphere can pass and the limitation relating to thegoing and rise, as shown on the previous page, it is generally notpracticable to have a completely rise...

  • Page 705

    Application † a straight flight for access to a domestic loftconversion only. This can provide one habitable room, plus abathroom or WC. The WC must not be the only WC in the dwelling.Practical issues † an economic use of space, achieved by a verysteep pitch of about 60° and opposing overlap...

  • Page 706

    Timber Stairs ~ these must comply with the minimum requirementsset out in Part K of the Building Regulations. Straight flight stairsare simple, easy to construct and install but by the introduction ofintermediate landings stairs can be designed to change direction oftravel and be more compact in ...

  • Page 707

    694Timber Stairs with Landings

  • Page 708

    For domestic situations a spiral stair of 800 mm clear width canprovide an alternative compact, space saving means of access tothe upper floor of a private dwelling. With a clear width of only600 mm this type of stair may also be used to access the spaceavailable in a roof void. Approved Document...

  • Page 709

    In-situ Reinforced Concrete Stairs ~ a variety of stair types andarrangements are possible each having its own appearance anddesign characteristics. In all cases these stairs must comply withthe minimum requirements set out in Part K of the BuildingRegulations in accordance with the purpose group...

  • Page 710

    697In-situ RC Stairs

  • Page 711

    Spiral and Helical Stairs ~ these stairs constructed in in-situreinforced concrete are considered to be aesthetically pleasing butare expensive to construct. They are therefore mainly confined toprestige buildings usually as accommodation stairs linking floorswithin the same compartment. Like all...

  • Page 712

    699In-situ RC Stairs

  • Page 713

    In-situ Reinforced Concrete Stair Formwork ~ in specific detail theformwork will vary for the different types of reinforced concretestair but the basic principles for each format will remain constant.700In-situ RC Stairs---Formwork

  • Page 714

    Precast Concrete Stairs ~ these can be produced to most of theformats used for in-situ concrete stairs and like those must complywith the appropriate requirements set out in Part K of the BuildingRegulations. To be economic the total production run must besufficient to justify the costs of the mo...

  • Page 715

    702Precast Concrete Stairs

  • Page 716

    703Precast Concrete Stairs

  • Page 717

    Precast Concrete Spiral Stairs ~ this form of stair is usuallyconstructed with an open riser format using tapered treads whichhave a keyhole plan shape. Each tread has a hollow cylinder at thenarrow end equal to the rise which is fitted over a central steelcolumn usually filled with in-situ concr...

  • Page 718

    Metal Stairs ~ these can be produced in cast iron, mild steel oraluminiumalloyforuseasescapestairsorforinternalaccommodation stairs. Most escape stairs are fabricated from castiron or mild steel and must comply with the Building Regulationrequirementsforstairsingeneralandfireescapestairsinparticu...

  • Page 719

    706Metal Stairs

  • Page 720

    707Metal Stairs

  • Page 721

    Balustrades and Handrails ~ these must comply in all respects withthe requirements given in Part K of the Building Regulations and inthe context of escape stairs are constructed of a non†combustiblematerial with a handrail shaped to give a comfortable hand grip.The handrail may be covered or ca...

  • Page 722

    Institutional and Assembly Stairs ~ Serving a place where asubstantial number of people will gather.minimum going, 280 mm (may reduce to 250 mm if the building floor area <100 m2), maximum, 340 mm The maximum pitch for gangways with seated spectators in assembly buildings is 35ƒ. ...

  • Page 723

    Measurement of the going (AD K) ~<1 m50 mm minimum treadwidth at newel (see additionalrecommendation, next page)going measured atcentre of tread,(see next page),minimum for privatestairs 220 mm, otherapplications 250 mm= =For stair widths greater than 1 m, the going is measured at 270 mmfrom e...

  • Page 724

    Basic requirements ~• Lines of all risers to meet at one point, ie. the geometric centre.• Centre going to be uniform and not less than the going ofadjacent straight flights.• Centre going ‡ going of adjacent parallel tread.• Centre going £ 700 À (2¾ rise) in mm.• Going at newel po...

  • Page 725

    To check whether the design for winder flights will comply withrecommended dimensions, measurements can be taken from scaledrawings or calculations may be applied.Calculations ~Gc = 2Rc (sin … 2)where, Rc([W] E) (V) =÷++222Eg. W = 770 mmE = 150 mmV=16 mmRc ([])=÷++77021501622()Rc=++()385150...

  • Page 726

    Summary recommendations of BS 5395-2 ~Clear headroom ~ measured from the pitch line (consecutive treadnosings at the geometric stair centre) vertically to any overheadobstruction. Normally 2.000 m, but acceptable at 1.900 m within150 mm of the centre column.Landing ~ Minimum angle subtended at th...

  • Page 727

    BS 5395†2, Stair types:Category A ~A small private stair for use by a limited number of people whoare generally familiar with the stair. For example, an internal stairin a dwelling serving one room not being a living room or akitchen. Also, an access stair to a small room or equipment roomin an...

  • Page 728

    Functions ~ the main functions of any door are to:1. Provide a means of access and egress.2. Maintain continuity of wall function when closed.3. Provide a degree of privacy and security.Choice of door type can be determined by:†1. Position † whether internal or external.2. Properties required...

  • Page 729

    Internal Doors ~ these are similar in construction to the externaldoors but are usually thinner and therefore lighter in weight.716Internal Doors

  • Page 730

    Internal Door Frames and linings ~ these are similar in constructionto external door frames but usually have planted door stops anddo not have a sill. The frames are sized to be built in conjunctionwith various partition thicknesses and surface finishes. Linings withplanted stops ae usually emplo...

  • Page 731

    Doorsets ~ these are factory produced fully assembled prehungdoors which are supplied complete with frame, architraves andironmongery except for door furniture. The doors may be hung tothe frames using pin butts for easy door removal. Prehung doorsets are available in standard and storey height v...

  • Page 732

    Fire doorset ~ a ``complete unit consisting of a door frame and adoor leaf or leaves, supplied with all essential parts from a singlesource''. The difference between a doorset and a fire doorset is thelatter is endorsed with a fire certificate for the complete unit.When supplied as a collection o...

  • Page 733

    30 Minute Flush Fire Doors ~ these are usually based on therecommendationsgiveninBS8214.Awidevarietyofdoorconstructions are available from various manufacturers but theyall have to be fitted to a similar frame for testing as a doorset orassembly, including ironmongery.A door's resistance to fire ...

  • Page 734

    60 Minute Flush Fire Door ~ like the 30 minute flush fire doorshown on page 720 these doors are based on the recommendationsgiven in BS 8214 which covers both door and frame. A wide varietyof fire resistant door constructions are available from variousmanufacturers with most classified as having ...

  • Page 735

    Fire and Smoke Resistance ~ Doors can be assessed for bothintegrity and smoke resistance. They are coded accordingly, forexample FD30 or FD30s. FD indicates a fire door and 30 theintegrity time in minutes. The letter `s' denotes that the door orframe contains a facility to resist the passage of s...

  • Page 736

    Apertureswillreducethepotentialfireresistanceifnotappropriatelyfilled.Suitablematerialshouldhavethesamestandard of fire performance as the door into which it is fitted.Fire rated glass types ~• Embedded Georgian wired glass• Composite glass containing borosilicates and ceramics• Tempered an...

  • Page 737

    724Glazed Double Swing Doors

  • Page 738

    Plasterboard ~ a rigid board composed of gypsum sandwichedbetween durable lining paper outer facings. For ceiling applications,the following types can be used:Baseboard -1220¾ 900¾ 9.5 mm thick for joist centres up to 400 mm.1220¾ 600¾ 12.5 mm thick for joist centres up to 600 mm.Baseboard ha...

  • Page 739

    Suspended Ceilings ~ these can be defined as ceilings which arefixed to a framework suspended from main structure thus formingavoidbetweenthetwocomponents.Thebasicfunctionalrequirements of suspended ceilings are:†1. They should be easy to construct, repair, maintain and clean.2. So designed tha...

  • Page 740

    Classification of Suspended Ceiling ~ there is no standard methodof classification since some are classified by their function such asilluminated and acoustic suspended ceilings, others are classified bythe materials used and classification by method of constructionis also very popular. The latte...

  • Page 741

    Panelled Suspended Ceilings ~ these are the most popular form ofsuspended ceiling consisting of a suspended grid framework towhich the ceiling covering is attached. The covering can be of atile, tray, board or strip format in a wide variety of materials withan exposed or concealed supporting fram...

  • Page 742

    Decorative and Open Suspended Ceilings ~ these ceilings usuallyconsist of an openwork grid or suspended shapes onto which thelights fixed at, above or below ceiling level can be trained thuscreating a decorative and illuminated effect. Many of these ceilingsare purpose designed and built as oppos...

  • Page 743

    Functions ~ the main functions of paint are to provide:†1. An economic method of surface protection to building materialsand components.2. An economic method of surface decoration to building materialsand components.Composition ~ the actual composition of any paint can be complexbut the basic c...

  • Page 744

    Supply ~ paint is usually supplied in metal containers ranging from250millilitresto5litrescapacitytothecolourrangesrecommended in BS 381C (colours for specific purposes) and BS4800 (paint colours for building purposes).Application ~ paint can be applied to almost any surface providingthe surface ...

  • Page 745

    Painting ~ the main objectives of applying coats of paint to asurface are preservation, protection and decoration to give afinish which is easy to clean and maintain. To achieve theseobjectives the surface preparation and paint application must beadequate. The preparation of new and previously pa...

  • Page 746

    Paint Defects ~ these may be due to poor or incorrect preparationof the surface, poor application of the paint and/or chemicalreactions. The general remedy is to remove all the affected paintand carry out the correct preparation of the surface beforeapplying in the correct manner new coats of pai...

  • Page 747

    Joinery Production ~ this can vary from the flow production whereone product such as flush doors is being made usually with the aidof purpose designed and built machines, to batch production wherea limited number of similar items are being made with the aid ofconventional woodworking machines. Pu...

  • Page 748

    Purpose Made Joinery ~ joinery items in the form of doors,windows, stairs and cupboard fitments can be purchased as stockitems from manufacturers. There is also a need for purpose madejoinery to fulfil client/designer/user requirement to suit a specificneed, to fit into a non-standard space, as a...

  • Page 749

    736Joinery Production

  • Page 750

    Joinery Timbers ~ both hardwoods and softwoods can be used forjoinery works. Softwoods can be selected for their stability,durability and/or workability if the finish is to be paint but if it isleft in its natural colour with a sealing coat the grain texture andappearance should be taken into con...

  • Page 751

    Typical Hardwoods Suitable for Joinery Works ~1. Beech † hard close grained timber with some silver grain in thepredominately reddish yellow to light brown colour. Suitable forall internal joinery. Approximately density 700 kg/m3.2. Iroko † hard durable hardwood with a figured grain and isusu...

  • Page 752

    Composite Boards ~ are factory manufactured, performed sheetswith a wide range of properties and applications. The mostcommonsizeis2440¾ 1220 mmor2400¾ 1200 mminthicknesses from 3 to 50 mm.1. Plywood (BS EN 636) † produced in a range of laminatedthicknesses from 3 to 25 mm, with the grain of ...

  • Page 753

    4. Particle BoardChipboard (BS EN 319) † bonded waste wood or chip particles inthicknesses from 6 to 50 mm, popularly used for floors in 18 and22 mm at 450 and 600 mm maximum joist spacing, respectively.Sheets are produced by heat pressing the particles in thermosettingresins.Wood Cement Board ...

  • Page 754

    Plastics ~ the term plastic can be applied to any group ofsubstances based on synthetic or modified natural polymers whichduring manufacture are moulded by heat and/or pressure into therequired form. Plastics can be classified by their overall groupingsuch as polyvinyl chloride (PVC) or they can ...

  • Page 755

    Uses ~ to weather- and leak-proof junctions and abutmentsbetween separate elements and components that may be subjectto differential movement. Also to gap fill where irregularitiesoccur.Properties ~• thermal movement to facilitate expansion and contraction• strength to resist wind and other n...

  • Page 756

    Formed of polysulphide rubber, polyurethane, silicone or some butylrubbers.Applications ~• Polysulphide~fac¸ades,glazing,fireprotection,roadsandpaving joints. High modulus or hardness but not completelyelastic.• Polyurethane~generaluses,fac¸adesandcivilengineering.Highlyelasticandresilientt...

  • Page 757

    Prior to 2003, several separate British Standards existed toprovide use and application guidance for a range of sealantproducts.Asindependentpublicationsthesearenowlargelysuperseded, their content rationalised and incorporated into thecurrent standard, BS EN ISO 11600: Building construction. Join...

  • Page 758

    8 DOMESTIC SERVICESDRAINAGE EFFLUENTSSUBSOIL DRAINAGESURFACE WATER REMOVALROAD DRAINAGERAINWATER INSTALLATIONSDRAINAGE SYSTEMSDRAINAGE PIPE SIZES AND GRADIENTSWATER SUPPLYCOLD WATER INSTALLATIONSHOT WATER INSTALLATIONSCISTERNS AND CYLINDERSSANITARY FITTINGSSINGLE AND VENTILATED STACK SYSTEMSDOMES...

  • Page 759

    Effluent ~ can be defined as that which flows out. In buildingdrainage terms there are three main forms of effluent:-1 . Subsoil Water ~ water collected by means of special drainsfrom the earth primarily to lower the water table level inthe subsoil. It is considered to be clean and therefore requ...

  • Page 760

    Subsoil Drainage ~ Building Regulation C2 requires that subsoildrainage shall be provided if it is needed to avoid:-a) the passage of ground moisture into the interior of thebuilding orb) damage to the fabric of the building.Subsoil drainage can also be used to improve the stability of theground,...

  • Page 761

    Subsoil Drainage Systems ~ the lay out of subsoil drains willdepend on whether it is necessary to drain the whole site or if it isonly the substructure of the building which needs to be protected.The latter is carried out by installing a cut off drain around thesubstructure to intercept the flow ...

  • Page 762

    General Principles ~ a roof must be designed with a suitable falltowards the surface water collection channel or gutter which inturn is connected to vertical rainwater pipes which convey thecollected discharge to the drainage system. The fall of the roofwill be determined by the chosen roof cover...

  • Page 763

    750Surface Water Removal---Roofs

  • Page 764

    751Surface Water Removal---Paved Areas

  • Page 765

    Highway Drainage ~ the stability of a highway or road relies ontwo factors †1 . Strength and durability of upper surface2. Strength and durability of subgrade which is the subsoil onwhich the highway construction is laid.The above can be adversely affected by water therefore it may benecessary ...

  • Page 766

    Road Drainage ~ this consists of laying the paved area or road toa suitable crossfall or gradient to direct the run-off of surfacewater towards the drainage channel or gutter. This is usuallybounded by a kerb which helps to convey the water to the roadgullies which are connected to a surface wate...

  • Page 767

    Materials ~ the traditional material for domestic eaves gutters andrainwater pipes is cast iron but uPVC systems are very oftenspecifiedtodaybecauseoftheirsimpleinstallationandlowmaintenance costs. Other materials which could be considered arealuminium alloy, galvanised steel and stainless steel,...

  • Page 768

    external wall pipe clip, holderbat or spigot with projecting ears rainwater pipe rainwater shoe sealed access cover ground level drain coupling drain to surface water sewer or soakaway mass concrete bed ground floor external wall pipe clip, holderbat or spigot with projectings ears rainwater pipe...

  • Page 769

    Soakaways ~ provide a means for collecting and controlling theseapage of rainwater into surrounding granular subsoils. They arenot suitable in clay subsoils. Siting is on land at least level andpreferably lower than adjacent buildings and no closer than 5 m toa building. Concentration of a large ...

  • Page 770

    Drains ~ these can be defined as a means of conveying surfacewater or foul water below ground level.Sewers ~ these have the same functions as drains but collect thedischarge from a number of drains and convey it to the finaloutfall. They can be a private or public sewer depending on who isrespons...

  • Page 771

    Separate System ~ the most common drainage system in use wherethe surface water discharge is conveyed in separate drains andsewers to that of foul water discharges and therefore receives notreatment before the final outfall.758Drainage Systems

  • Page 772

    Combined System ~ this is the simplest and least expensive systemto design and install but since all forms of discharge are conveyedin the same sewer the whole effluent must be treated unless a seaoutfall is used to discharge the untreated effluent.Typical Example ~Ref. BS EN 752: Drain and sewer...

  • Page 773

    Partially Separate System ~ a compromise system † there are twodrains, one to convey only surface water and a combined drain toconvey the total foul discharge and a proportion of the surfacewater.760Drainage Systems

  • Page 774

    Inspection Chambers ~ these provide a means of access to drainagesystems where the depth to invert level does not exceed 1„000.Manholes ~ these are also a means of access to the drains andsewers, and are so called if the depth to invert level exceeds 1„000.These means of access should be posi...

  • Page 775

    Plastic Inspection Chambers ~ the raising piece can be sawnhorizontally with a carpenter's saw to suit depth requirements withthe cover and frame fitted at surface level. Bedding may be a100 mm prepared shingle base or 150 mm wet concrete to ensure auniform support.The unit may need weighting to ...

  • Page 776

    Means Of Access † provision is required for maintenance andinspection of drainage systems. This should occur at:* the head (highest part) or close to it* a change in horizontal direction* a change in vertical direction (gradient)* a change in pipe diameter* a junction, unless the junction can b...

  • Page 777

    Excavations ~ drains are laid in trenches which are set out,excavatedandsupportedinasimilarmannertofoundationtrenches except for the base of the trench which is cut to therequired gradient or fall.Joints ~ these must be watertight under all working and movementconditions and this can be achieved ...

  • Page 778

    Watertightness ~ must be ensured to prevent water seapage anderosion of the subsoil. Also, in the interests of public health, foulwatershouldnotescapeuntreated.TheBuildingRegulaions,Approved Document H1: Section 2 specifies either an air or watertest to determine soundness of installation.AIR TES...

  • Page 779

    Drainage Pipes ~ sizes for normal domestic foul water applications:-<20 dwellings= 100 mm diameter20†150 dwellings = 150 mm diameterExceptions: 75 mm diameter for waste or rainwater only (no WCs)150 mm diameter minimum for a public sewerOther situations can be assessed by summating the Disch...

  • Page 780

    Water supply ~ an adequate supply of cold water of drinkingquality should be provided to every residential building and adrinking water tap installed within the building. The installationshould be designed to prevent waste, undue consumption, misuse,contamination of general supply, be protected a...

  • Page 781

    768Water Supply---Basic Requirements

  • Page 782

    General ~ when planning or designing any water installation thebasic physical laws must be considered:-1 . Water is subject to the force of gravity and will find its ownlevel.2. To overcome friction within the conveying pipes water which isstored prior to distribution will require to be under pre...

  • Page 783

    Indirect Systems ~ Cold water is supplied to all outlets from a coldwater storage cistern except for the cold water supply to thesink(s) where the drinking water tap is connected directly toincoming supply from the main. This system requires more pipeworkthan the direct system but it reduces the ...

  • Page 784

    Direct System ~ this is the simplest and least expensive system ofhot water installation. The water is heated in the boiler and thehot water rises by convection to the hot water storage tank orcylinder to be replaced by the cooler water from the bottom ofthe storage vessel. Hot water drawn from s...

  • Page 785

    Indirect System ~ this is a more complex system than the directsystem but it does overcome the problem of furring which canoccur in direct hot water systems. This method is thereforesuitable for hard water areas and in all systems where a centralheating circuit is to be part of the hot water inst...

  • Page 786

    Mains Fed Indirect System ~ now widely used as an alternative toconventional systems. It eliminates the need for cold water storageandsavesconsiderablyoninstallationtime.Thissystemisestablished in Europe and the USA, but only acceptable in the UKat the local water authority's discretion. It compl...

  • Page 787

    Flow Controls ~ these are valves inserted into a water installationto control the water flow along the pipes or to isolate a branchcircuit or to control the draw-off of water from the system.crutch head packing gland STOP VALVE high pressure mains supply spindle loose jumper flow GATE VALVE low p...

  • Page 788

    Cisterns ~ these are fixed containers used for storing water atatmospheric pressure. The inflow of water is controlled by afloatvalve which is adjusted to shut off the water supply when ithas reached the designed level within the cistern. The capacity ofthe cistern depends on the draw off demand ...

  • Page 789

    Indirect Hot Water Cylinders ~ these cylinders are a form of heatexchanger where the primary circuit of hot water from the boilerflows through a coil or annulus within the storage vessel andtransfers the heat to the water stored within. An alternative hotwater cylinder for small installations is ...

  • Page 790

    777Water Installations---Pipework Joints

  • Page 791

    Fireclay Sinks (BS 1206) † theseare white glazed sinks and areavailable in a wide range of sizesfrom 460¾ 380¾ 200 deepup to 1220¾ 610¾ 305 deepand can be obtained with anintegral drainer. They should befixed at a height between 850and 920 mm and supported by legs,cantilever brackets or dwa...

  • Page 792

    779Sanitary Fittings---Baths and Showers

  • Page 793

    780Sanitary Fittings---Water Closets and Cisterns

  • Page 794

    Single Stack System ~ method developed by the Building ResearchEstablishment to eliminate the need for ventilating pipework tomaintain the water seals in traps to sanitary fittings. The slopeand distance of the branch connections must be kept within thedesign limitations given below. This system ...

  • Page 795

    VentilatedStackSystems~wherethelayoutofsanitaryappliances is such that they do not conform to the requirementsfor the single stack system shown on page 781 ventilating pipeswill be required to maintain the water seals in the traps. Threemethods are available to overcome the problem, namely a full...

  • Page 796

    Airtightness ~ must be ensured to satisfy public health legislation.TheBuildingRegulations,ApprovedDocumentH1:Section1,provides minimum standards for test procedures. An air or smoketest on the stack must produce a pressure at least equal to 38 mmwater gauge for not less than 3 minutes.NB. Smoke ...

  • Page 797

    One Pipe System ~ the hot water is circulated around the systemby means of a centrifugal pump. The flow pipe temperature beingabout 80°C and the return pipe temperature being about 60 to70°C. The one pipe system is simple in concept and easy to installbut has the main disadvantage that the hot ...

  • Page 798

    Two Pipe System ~ this is a dearer but much more efficient systemthan the one pipe system shown on the previous page. It is easierto balance since each radiator or heat emitter receives hot waterat approximately the same temperature because the hot waterleaving the radiator is returned to the boi...

  • Page 799

    Micro Bore System ~ this system uses 6 to 12 mm diameter softcopper tubing with an individual flow and return pipe to each heatemitter or radiator from a 22 mm diameter manifold. The flexibleand unobstrusive pipework makes this system easy to install inawkward situations but it requires a more po...

  • Page 800

    Controls ~ the range of controls available to regulate the heatoutput and timing operations for a domestic hot water heatingsystem is considerable, ranging from thermostatic radiator controlvalves to programmers and controllers.Typical Example ~Boiler † fitted with a thermostat to control the t...

  • Page 801

    Electrical Supply ~ in the UK electricity is generated mainly fromgas, coal, nuclear and hydro-electricity power plants. Alternativeenergy generation such as wind and solar power are also viableand considered in Part 16 of theBuilding Services Handbook.Distribution is through regional companies. ...

  • Page 802

    Electrical Supply Intake ~ although the electrical supply intake canbe terminated in a meter box situated within a dwelling, mostsupply companies prefer to use the external meter box to enablethe meter to be read without the need to enter the premises.For alternative arrangement of supply intake ...

  • Page 803

    Entry and Intake of Electrical Service ~ the local electricity supplycompany is responsible for providing electricity up to and includingthemeter,buttheconsumerisresponsibleforsafetyandprotection of the company's equipment. The supplier will install theservice cable up to the meter position where...

  • Page 804

    Consumer's Power Supply Control Unit † this is convenientlyabbreviated to consumer unit. As described on the previous page,it contains a supply isolator switch, live, neutral and earth bars,plus a range of individual circuit over-load safety protectiondevices. By historical reference this unit ...

  • Page 805

    Electric Cables ~ these are made up of copper or aluminium wirescalled conductors surrounded by an insulating material such asPVC or rubber.Conduits ~ these are steel or plastic tubes which protect thecables. Steel conduits act as a cpc to earth whereas plasticconduits will require a separate cpc...

  • Page 806

    Wiring systems ~ rewireable systems housed in horizontal conduitscan be cast into the structural floor slab or sited within the depthof the floor screed. To ensure that such a system is rewireable,draw-in boxes must be incorporated at regular intervals and notmore than two right angle boxes to be...

  • Page 807

    Cable Sizing ~ the size of a conductor wire can be calculatedtaking into account the maximum current the conductor will haveto carry (which is limited by the heating effect caused by theresistance to the flow of electricity through the conductor) andthe voltage drop which will occur when the curr...

  • Page 808

    Power Sockets ~ in new domestic electrical installations the ringfinal circuit is usually employed instead of the older obsolete radialsystem where socket outlets are on individual fused circuits withunfused round pin plugs. Ring circuits consist of a fuse or miniaturecircuit breaker protected su...

  • Page 809

    Lighting Circuits ~ these are usually wired by the loop-in methodusing a line, neutral and circuit protective conductor to earthcable with a 6 amp fuse or miniature circuit breaker protection. Incalculatingtheratingofalightingcircuitanallowanceof100 watts per outlet should be used. More than one ...

  • Page 810

    Gas Supply ~ potential consumers of mains gas may apply to theirlocal utilities supplier for connection, e.g. Transco (Lattice Groupplc). The cost is normally based on a fee per metre run. However,where the distance is considerable, the gas authority may absorbsome of the cost if there is potenti...

  • Page 811

    Gas Service Pipes ~1 . Whenever possible the service pipe should enter the buildingon the side nearest to the main.2. A service pipe must not pass under the foundations of abuilding.3. No service pipe must be run within a cavity but it may passthrough a cavity by the shortest route.4. Service pip...

  • Page 812

    Gas Fires ~ for domestic use these generally have a low energyrating of less than 7 kW net input and must be installed inaccordance with minimum requirements set out in Part J of theBuilding Regulations. Most gas fires connected to a flue aredesigned to provide radiant and convected heating where...

  • Page 813

    Gas Fire Flues ~ these can be defined as a passage for thedischarge of the products of combustion to the outside air and canbe formed by means of a chimney, special flue blocks or by using aflue pipe. In all cases the type and size of the flue as recommendedin Approved Document J, BS EN 1806 and ...

  • Page 814

    Open Fireplaces ~ for domestic purposes these are a means ofproviding a heat source by consuming solid fuels with an outputrating of under 50 kW. Room-heaters can be defined in a similarmanner but these are an enclosed appliance as opposed to theopen recessed fireplace.Components ~ the complete c...

  • Page 815

    Open Fireplace Recesses ~ these must have a constructionalhearth and can be constructed of bricks or blocks of concrete orburnt clay or they can be of cast in-situ concrete. All fireplacerecesses must have jambs on both sides of the opening and abacking wall of a minimum thickness in accordance w...

  • Page 816

    803Open Fireplace and Flues

  • Page 817

    Open Fireplace Chimneys and Flues ~ the main functions of achimney and flue are to:-1 . Induce an adequate supply of air for the combustion of thefuel being used.2. Remove the products of combustion.In fulfilling the above functions a chimney will also encourage aflow of ventilating air promoting...

  • Page 818

    Refs. BS EN 13502: Chimneys. Requirements and test methods forclay/ceramic flue terminals.BS EN 1457: Chimneys. Clay/ceramic flue liners. Requirements andtest methods.BS EN 771-1: Specification for (clay) masonry units.805Open Fireplace and Flues

  • Page 819

    806Open Fireplaces and Flues

  • Page 820

    Chimney construction †Typical chimney outletClay bricks † Frost and thaw, severe exposure resistant quality.Min. density 1500 kg/m3.Calcium silicate bricks † Min. compressive strength 20.5 N/mm2(27.5 N/mm2 for cappings).Precast concrete masonry units † Min. compressive strength 15 N/mm2.M...

  • Page 821

    Combustion Air ~ it is a Building Regulation requirement that inthe case of open fireplaces provision must be made for theintroduction of combustion air in sufficient quantity to ensure theefficient operation of the open fire. Traditionally such air is takenfrom the volume of the room in which th...

  • Page 822

    Lightweight Pumice Chimney Blocks ~ these are suitable as a fluesystem for solid fuels, gas and oil. The highly insulative propertiesprovide low condensation risk, easy installation as a supplement toexisting or on-going construction and suitability for use withtimber frame and thatched dwellings...

  • Page 823

    Fire Protection of Services Openings ~ penetration of compartmentwalls and floors (zones of restricted fire spread, e.g. flats in onebuilding), by service pipes and conduits is very difficult to avoid.Anexceptioniswherepurposebuiltserviceductscanbeaccommodated. The Building Regulations, Approved ...

  • Page 824

    Telephone Installations ~ unlike other services such as water, gasand electricity, telephones cannot be connected to a commonmains supply. Each telephone requires a pair of wires connectingit to the telephone exchange. The external supply service andconnectiontothelead-insocketiscarriedoutbytelec...

  • Page 825

    Electronic Installations † in addition to standard electrical andtelecommunicationsuppliesintobuildings,thereisagrowingdemand for cable TV, security cabling and broadband access to theInternet. Previous construction practice has not foreseen the needto accommodate these services from distributi...

  • Page 826

    INDEXAccess for disabled, 492À4Access to sites, 88Accommodation on sites, 89À90Active earth pressures, 251, 263À4Adhesives, 556Admixtures, 272, 356Aerated concrete floor units, 673Aggregate samples, 108Air lock hopper, 230Air test, 765, 783Air tightness, infiltration and permeability,477, 480,...

  • Page 827

    Bolted connections, 537À8, 541BoltsÀ types, 541Bonding, bricks, 323À9Bonnet tiles, 431, 437Boot lintels, 362Bore hole, 72, 80Borrowed light, 634Bottom shore, 155Bowstring truss, 573, 575Box beam, 557Box caisson, 292Box pile foundation, 236, 240Braced structures, 561Breather membrane, 409À10, ...

  • Page 828

    Cement grouts, 311Central heating, 784À7Centres, 359, 361Certificates of ownership, 42, 46Channel floor units, 674ChannelsÀ structural steel, 532À3Checked rebates in walls, 365Chemical dpc, 347À8Chemical grouts, 311Cheshire auger, 78Chezy formula, 766Chimney pot, 22, 805, 809Chimneys, 801, 80...

  • Page 829

    Controlling dimensions, 48Controlling grid and lines, 47À8Cooker circuit cable, 794Coping stones, 248, 252À3, 341Corbelled brickwork, 335À6, 805, 807Core drilling, 79Core structures, 561Cored floor units, 674CORGI, 479Cor-ply beam, 557Cornice, 736Corrugated sheet, 564À8Coulomb’s line, 86Cou...

  • Page 830

    proportional depth, 766rainwater, 754À6roads, 752À3roofs, 750simple, 757À64systems, 757À60testing, 765Drained cavities, 276Draught proofing, 491Drawings:axonometric projection, 24construction process, 21hatchings, symbols and notation, 38À41isometric projection, 24orthographic projection, 23...

  • Page 831

    Flat roofs, 417, 447À56, 461, 466Flat sawn timber, 554Flat slabs, 496À8, 668Flat top girder, 569, 572Flemish bond, 326Flexible paving, 133Flight auger, 78, 234Flitch beam, 557Float valves, 774À5Floating floor, 651, 683À4Floating pile foundation, 228Floor plans, 26, 41Floor springs, 724Floors:...

  • Page 832

    Ground water control, 303À12Grouting-subsoil, 311Grouting-tiles, 646Guard rail, 141À3, 145, 147, 150À1Gusset base, 539Gusset plate, 552, 563, 566Half hour fire door, 720Hammer head junction, 132Hand auger, 78Hand auger holes, 73Handrail, 685À6, 688, 690, 693À5, 698À9,704À6, 708, 710À11Har...

  • Page 833

    Kerbs, 137Kelly bar, 231À4Kentledge, 149, 247, 301Kitemark, 63Laboratory analysis of soils, 72, 81À2,85À7Ladders, 141À2, 145Laminated timber, 553À6Land caissons, 292Land reclamation, 318Landings, 693À706Lantern lights, 592Large diameter piled foundations, 229, 233Larssen sheet piling, 291La...

  • Page 834

    Multi-stage wellpoints, 306Multi-storey structures, 560À1National Building Specification, 67Needle and pile underpinning, 298Needle design, 159À60Needles, 153À60Newel post, 685, 688, 690À1, 693À5,710À11NHBC, 28, 58Non-load-bearing partitions, 618, 620,629À34Non-residential buildings, 330À...

  • Page 835

    Pitched trusses, 424À5, 562À3, 569À70Pivot window, 367, 375Placing concrete, 198Plain tiles and tiling, 410À14, 430À4,437À8Planer, 734Plank and pot floor, 674Planning application, 42À6Planning grid, 47Plant:bulldozer, 171concreting, 198À204considerations, 89, 168costing, 169cranes, 186À9...

  • Page 836

    foundations, 220À2, 224À6lintels, 362pile caps and beams, 232, 247raft foundation, 222, 226reinforcement, 497À513retaining walls, 254slabs, 496À9, 501À3stairs, 696À700strip foundations, 220, 224Reinforced masonry, 258À9, 328, 625Reinforcement:bar coding and schedules, 508À9concrete cover,...

  • Page 837

    Sanitary fittings (continued)bath, 779discharge systems, 781À2shower, 779sink, 778wc pan, 780Sanitation systems, 781À3Sanitation system testing, 783Sapele, 738Sarking felt, 430Sash weights, 372Saws, 734Scaffolding:birdcage, 148boards, 141À3cantilever, 150component parts, 140, 146fittings, 146g...

  • Page 838

    Slab base, 539Slates and slating, 441À5Slenderness ratio, 160À1, 355, 547Sliding doors, 396À8Sliding sash windows, 372À4Slump test, 109Slung scaffold, 148Small diameter piled foundation, 221,229À32Smoke seal, 722Smoke test, 783Snow loading, 218, 544Soakaway, 756Soakers, 411À12, 438, 444, 80...

  • Page 839

    Structure (continued)functions, 15À16protection orders, 123Strut design, 161, 631Strutting of floors, 659Stud partitions, 629À33Subsoil:drainage, 747À8, 752movements, 207À11water, 70, 72, 80, 302Substructure, 11Sump pumping, 303Supply and storage of concrete, 198Supported static tower crane, ...

  • Page 840

    Tremie pipe, 231, 309Trench fill foundation, 213, 224Trench setting out, 126Trench sheeting, 283, 290À1Trial pits, 73À4, 77Triangle of forces, 249, 264Triangular chart, 82Triaxial compression test, 86Triple glazing, 385À6Tripod rig, 78À9, 230Truss out scaffold, 151Trussed purlin, 426, 557Trus...

  • Page 841

    Water installations (continued)supply, 767À8valves and taps, 774Water jetting, 304À6, 315Water table, 70, 72, 80, 302Water test, 765Waterproofing basements, 272À6Weatherboarding, 410Web cleats, 537À8Weep holes, 248À54, 362, 365Weight batching, 287Weights of materials, 35À6Welded connections...