Flat roofs and balconies CHAPTER 7.1 This chapter gives guidance on meeting the Technical Requirements for flat roofs and balconies. Waterproofing using profile sheet is outside the scope of this chapter.

7.1.1 Compliance 01 7.1.2 Provision of information 01 7.1.3 Flat roof and balcony design 01 7.1.4 Timber and timber decks 02 7.1.5 Profiled metal decks 04 7.1.6 Concrete decks 04 7.1.7 Thermal insulation and vapour control 05 7.1.8 Waterproofing and surface treatments 05 7.1.9 Green and proprietary roofs 07 7.1.10 Detailing of flat roofs 09 7.1.11 Accessible thresholds 11 7.1.12 Drainage 12 7.1.13 Guarding to balconies 14

Also see: Chapter 2.1 true and free from twists or sagging. include support steelwork and purlins which are square, have restraint straps at 2m centres (maximum) where joists or concrete beams are parallel to walls. Details at critical junctions. Details of fixings and fixing methods, including those for insulation and surfacing. Specification for intensive, or extensive green roofs. Details and fixing methods of balcony support and guarding components. have adequate provision for movement in larger roofs, particularly where the span of the roof deck changes, Mastic Asphalt Council (MAC) Mastic (SPRA) Association Single Ply Roofing (LRWA). Association Waterproofing Liquid Roofing and e.g. in L-shaped buildings; joints should be continuous through the vertical upstands, walls and edges of the building „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „

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A roof with a maximum slope of 10° from the horizontal. Systems may be used at a greater pitch of 10° from the horizontal. Systems may roof with a maximum slope A held in place. and materials are adequately requirements of this chapter, where they meet the of the flat roof. The structural substrate surface of the balcony. The upper trafficked deck. Insulated above the deck. Insulated below the waterproofing. Insulated above the contained within soil. Vegetation contained in the sedum. Vegetation Flat roof and balcony design balcony and Flat roof

CHAPTER 7.1 Flat roofs and balconies and roofs Flat Compliance

flat roof is to act as a roof terrace, roof garden or car parking area have a minimum bearing of 90mm, or have adequate provision for the additional loads where a resist wind uplift by either being of sufficient self-weight or by being anchored to the main structure – where required, holding-down straps should be provided at a maximum spacing of 2m be produced by an engineer in accordance with Technical Requirement R5, and be in accordance with Technical BS EN 1991-1-1, BS EN 1991-1-3 and BS EN 1991-1-4 Size, specification and position of the components, Sections through the construction, indicating how falls are formed and ventilation is provided. Extent and direction of falls, and position of rainwater Extent and direction of falls, and position outlets. including treatments for durability and the position of the insulation and waterproofing layers. vapour control layer, National Federation of Roofing Contractors (NFRC) National Federation of Roofing Contractors BS 6229 ‘Flat roofs with continuously supported coverings. BS 6229 ‘Flat roofs with continuously supported Code of practice’ „ „ „ „ „ „ „ „ „ Deck Decking roof Warm Cold roof Inverted warm roof Intensive green roof Extensive green roof Flat roof The structural design of flat roofs and balconies should: 7.1 . 3 the structure. Flat roofs and balconies shall support and transmit loads safely to Design and specification information should be issued to site supervisors, relevant specialist subcontractors and suppliers, be issued to site supervisors, relevant specialist subcontractors and suppliers, Design and specification information should Designs and specifications shall be produced in a clearly understandable format, include all relevant be produced in a clearly understandable format, include all relevant Designs and specifications shall all appropriate personnel. information and be distributed to Provision of information of Provision 7.1.2 Flat roofs and balconies shall comply with the Technical Requirements. with the Technical Flat roofs and balconies shall comply the guidance in this chapter will generally be acceptable to NHBC. Flat roofs and balconies which comply with Other sources of information include: 7.1.1 and include the following information: this chapter for Definitions apply: following definitions the of this chapter, For the purposes Where joists and concrete roof elements are used to provide lateral restraint, they should: Where joists and concrete roof elements are used to provide lateral restraint, they Where the flat roof or balcony is a terrace above another home, it should provide satisfactory acoustic performance in above another home, it should provide satisfactory acoustic performance in Where the flat roof or balcony is a terrace accordance with relavant building regulations. „ „ „ „ „ „ „ „ „ 1

1 7.1 „ „ „ „ „ „ „ „ „ „ „ „ Decking boardsshouldbespecifiedandfixedinaccordance with: used for: Timber inbalconiesshouldbelimitedtoelementswhicharesupported bymaterialsotherthantimber. Timber shouldnotbe Structural elementsofbalconiesshouldhaveaservicelifeatleast60years. Table 1: Timber decks should: Timber shouldbe: Structure anddurability b) a) satisfactory substrateforthewaterproofingsystem.Issuestobetakenintoaccountinclude: Timber flatroofsandbalconiesshallbeofadequatestrengthdurability, andbeinstalledtoforma .4 7.1 Material Maximum boardwidth100mm Pretreated timberplanking,tongueandgrooved(closeboardedtimber) Oriented strandboard,typeOSB3 Plywood toBSEN636,Class3 „ „ „ „ „ „ „ „ „ „ „ „ Association, or guidance fromthe Timber DeckingandCladding guardrails ortheirsupport posts orcolumnssupportingabalcony gallows bracketssupportingabalcony where anypartofthejoistisexposedtoexternalconditions recommendationsandnotused with themanufacturer’s have I-joistsormetalwebjoistsspecifiedinaccordance marked ‘DRY’ or‘KD’ wheresoftwoodisusedinternally be fromregularisedtimber, drygradedtoBS4978and regulations span tablespublishedby TRADA insupportofbuilding be inaccordanceBSEN1995-1-1orappropriateload/ cut. preservative, wherepreservativetreatedtimberhasbeen retreated alongthecutedgeswithacoloured timber)’ with Chapter3.3‘Timber preservation(naturalsolid preservative treatedornaturallydurable,inaccordance stored undercovertopreventwetting suitable qualityorshape rejected whereexcessivelywet,damagedornotofa checked forconformitywiththedesignupondelivery joist hangers,strapsandstrutting structure anddurability Timber andtimberdecks Materials usedfordecks

„ „ „ „ „ „ „ c) „ „ „ „ „ „ „ the designandatamaximumof600mmcentres have joistswhicharesizedandspacedinaccordancewith Requirement R5. design,inaccordancewith Technicalan engineer’s infill joists. cantilevered decksorjoists formed withoneofthematerialslistedin Table 1. packing, includingtimber, shouldnot beused) tiles orslatesbeddedinmortartoadjustjoists(loosesoft be leveland,wherenecessary, usinghardpackingsuchas waterproofing istobeinstalledimmediately be temporarilycoveredtopreventwetting,unlessthe installing timbersubstrates. Flat roofs andbalconies 450mm joistcentres Thickness ofdeck(mm) 19 15 15 treatment surface firrings ortaperedinsulation falls canbecreatedby waterproofin 7.1 CHAPTER g 600mm joistcentres 19 18 18 finish ceiling joist andfirring deck vapour controllayer insulatio n

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2 2 7.1 m strap with 30x2.5mm cross section and min. 1000mm long min 4 screw fixings per strap from bottom of strap lowest fixing max. 150m be fixed at a maximum of 100mm centres (unless the design specifies closer) be fixed with flat-headed ring shank nails (50mm long x 3mm for plywood, 3mm x 2.5 x board thickness for OSB). not prevent cross ventilation in cold deck roofs. not prevent cross ventilation in cold deck joints in sheet materials which are precovered or coated should be sealed immediately after fixing by materials that have been damaged or adversely affected moisture should be discarded. be supported on noggings where the edges of boards situated along the roof perimeter do not coincide with joists fixed in accordance with the design. fixed in accordance fixing secured within 150mm of the fixed with the lowest strap bottom of the vertical 1m long 30mm x 2.5mm and predrilled for fixings. „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ Rows of strutting None needed One (at centre of span) Equally spaced along the span at maximum 2.5m centres

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notched to keep ceiling line leve gap between joist and hanger is 6mm max.

Spacing for strutting the hanger and the wall no gap between CHAPTER 7.1 Flat roofs and balconies and roofs Flat

have a maximum movement gap between boards of 3mm for square edge boards have a minimum movement gap of 10mm where boards abut a rigid upstand have tongued and grooved boards installed with the long edge at right angles to the joists, and short edges supported on a joist or nogging the area of deck installed should be of a size which can be quickly covered in the event of rain conditions should be dry, and materials protected from conditions should be dry, wetting until the roof is complete be either herringbone type (timber 38mm x 38mm), be either herringbone type (timber 38mm depth of joist) solid blocking (38mm thick timber x 0.75 or proprietary steel strutting spaced at a maximum of 2m centres spaced at a maximum of four hardened nails 4mm in fixed with a minimum or No 12. wood screws x 50mm diameter x 75mm long, fixed to masonry) long, into plugs (where the correct size for the timber joist or trimmer the correct size for the in accordance with BS 845-1 in accordance with BS „ „ „ „ „ „ „ „ „ „ Up to 2.5 2.5-4.5 Over 4.5 Joist span (m) When installing timber substrates: Installing timber substrates Table 2: Table Strutting should be provided to prevent excessive movement, and:: Strutting should be provided to prevent Joist hangers, straps and strutting straps and Joist hangers, at the correct height. should be level and joist hangers Masonry carrying in accordance with BS EN 845-1. fixings should be protected against corrosion Mild steel straps and be: Joist hangers should Plywood and oriented strand board should: Where holding-down straps are required to prevent the roof from lifting from the supporting structure, they should be: from lifting from the supporting structure, straps are required to prevent the roof Where holding-down „ „ „ „ „ „ „ „ „ „ 3

3 7.1 „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ Precast concretedecksshould: Softwood tonguedandgroovedboardingshouldbe: In-situ reinforcedconcretedecksshould: accordance withBSEN1992-1-1andChapter3.1‘Concrete anditsreinforcement’. Concrete flatroofsshouldbeconstructedtoensuretheyachieve therequireddesign,strengthanddurability Concrete flatroofsandbalconiesshallformasatisfactory substrateforthewaterproofingsystem. 7.1.6 Concrete decks Profiled metalflatroofsshould: Profiled metalflatroofsandbalconiesshallformasatisfactorysubstrateforthewaterproofingsystem. 7.1.5 Profiled metal decks OSB shouldbe: „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ be grouted, asspecified inthedesign. be installedto provide anevensurface and atabutments have allowanceformovement approximatelyevery15m have allowanceforcontinuity or anti-crackreinforcement specifies asmallerdimension) have aminimum90mmbearing (unlessthedesign be installedonanevenandtrue supportingstructure supported formwork have accuratelyconstructedandsuitably shrinkage characteristics be formedusingamixwhichhaslow width (forbondedsystems) have acrownwhichisminimumof50%theprofile 485-2 andusedinaccordancewithBSEN1993-1-3 be galvanisedsteeltoBSEN10147oraluminium instructions fixed inaccordancewiththemanufacturer’s resist loadsinaccordancewithBSEN1991-1-4andbe the relevantappliedsafetyfactor loadandspantables comply withthemanufacturer’s be suitablystoredtopreventdamage design upondelivery and durability, andbecheckedforconformitywiththe be constructedtoensuretheyachievetherequiredstrength nail headspunchedbelowthetimbersurface. fixed withtworingshanknailstoeachjoistorfirring, closely clampedtogetherwithendjointsstaggered fixed aminimumof9mmfromtheedgeboard. the supportingjoists boards, withthestrongeraxisinstalledatrightanglesto installed oversupportsinthedirectionindicatedon firrin falls canbecreatedby treatment surface g s orta p ered insulation waterproofing

plasterboar plaster or profiled metaldec vapour controllayer insulation

d k

„ „ „ „ „ „ „ „ „ „ „ „ and insulationsystemisinstalled. be ofsuitablequalityandfinishbeforethewaterproofing be adequatelyprotectedfromconstructionloads variations approvedbythedesigner be fixedandinstalledinaccordancewiththedesign layer (unlessthemanufacturerrecommendsotherwise) be sidestitchedtoensureitperformsasacontinuousplane width (formechanicallyfixedsystems) have acrownwhichisminimumof45%theprofile deck hasfullydried). (permanent waterproofingshouldnotbeinstalleduntilthe be protecteduntiladequatelycuredanddried Flat roofs andbalconies screed ortaperedinsulation falls canbecreated by treatment surface OSB andplywood boards, 3mmfor for squareedge profile widt crown widt h waterproofin 7.1 CHAPTER

h g a rigidupstand or plywoodabut 10mm whereOSB plasterboard plaster or concrete deck screed tofalls vapour controllayer insulatio , andbein n

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4 4 7.1

s

k

h avoiding risks’ and BS 5250 and avoiding risks’ d noggings are required to support all cross joint ensure adequate bearing area for composite dec two continuous beads of sealant beneat each boar Also see: BRE Report ‘Thermal insulation: BRE Report ‘Thermal Also see: surface treatments. the surface should be even and dry and nails should be punched below the surface the manufacturer’s recommendations for conditioning, and unrolling in advance of laying, should be followed concrete and screed surfaces should be adequately dry. suitable for the weight of the ballast and able to withstand suitable for the weight of the ballast and anticipated traffic fines from protected by a geo-textile layer to prevent reaching the membrane surface. used, the vapour where a mechanically fixed system is sheet control layer should consist of suitable polyethylene sealed at all laps. kept dry and installed in quantities which can be quickly kept dry and installed aid bonding and to avoid covered if it rains (to trapping moisture). (openings at both ends of adequate cross ventilation each joist void). „ „ „ „ „ „ „ „ c) „ „ „ „ „ „ „ „

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CHAPTER 7.1 Flat roofs and balconies and roofs Flat

Thermal insulation and vapour control vapour insulation and Thermal

installation of waterproofing waterproofing systems should be followed to achieve a satisfactory bond with the waterproofing the manufacturer’s recommendations for preparation, including priming upstands, roof outlets, etc. the structure and receiving surface should be checked and approved by the waterproofing contractor sealed at laps to the waterproofing, at the perimeter and at each penetration, e.g. at outlets and pipes (where the roof is a single-ply system, the vapour control is generally not sealed to the waterproofing). include at least one layer of bitumen roofing membrane include at least one layer of bitumen roofing or mechanically (S2P3) below the insulation, fully bonded or a suitable fixed to the structural deck as appropriate, self-adhesive or torch-on membrane. extruded polystyrene (XPS), extruded polystyrene with a extruded polystyrene (XPS), extruded polystyrene in accordance cementitious surface or suitably assessed Requirement R3 Technical with suitable for external use the insulation joint at the have two beads of sealant along each board of the vapour foil underface (to maintain the integrity control layer). an unobstructed 50mm ventilation space above an unobstructed 50mm an effective vapour control layer at ceiling level vapour control layer an effective bonded or mechanically fixed in accordance with the bonded or mechanically manufacturer’s recommendations; where mechanically using fixings of sufficient length fixed, it should be installed penetration into the supporting structure to ensure adequate „ „ „ „ „ „ „ „ „ „ Prior to the waterproofing being installed: Installation of waterproofing Flat roofs, and balconies forming roofs, shall adequately resist the passage of water to the inside of the Flat roofs, and balconies forming roofs, shall adequately resist the building. Issues to be taken into account include: a) b) Waterproofing and surface treatments and surface Waterproofing 7.1.8 Insulation for inverted roofs should be: Insulation should be: 7.1 .7 and prevent the performance, satisfactory shall ensure control and ventilation insulation, vapour Thermal affect the construction. which could adversely formation of condensation Vapour control layers should be provided to warm roofs, and: control layers should be provided Vapour Cold flat roofs are difficult to detail correctly but, where used, they should be in accordance with BS 5250 and have: they should be in accordance with difficult to detail correctly but, where used, Cold flat roofs are Composite decks should: „ „ „ „ „ „ „ „ „ „ 5

5 7.1 „ „ „ „ „ „ „ „ „ Polymer modifiedasphaltshould beassessedinaccordancewith Technical RequirementR3. Inverted roofsshould: temperatures, andcanprovidealongerservicelife. Elastomeric (i.e.SBSpolymer-modified)bitumenmembranes offer increasedextensibilityandflexibility, especiallyatlow Torching ontoinsulationboards,except rockwoolorperlite,isnotacceptable. Mastic asphaltshouldbe: Mastic asphalt Table 3: 5B/250 toBS8747(type5reinforcedbitumenmembranesarecolour-codedblueforidentification). Reinforced bitumenmembraneshouldbehighperformanceandreinforcedwithpolyesterreinforcement,e.g.type5U, 5B/180, Reinforced bitumenmembrane Waterproofing systems Waterproofing shouldbe: the following: waterproofing. Issuestobetakenintoaccountinclude Environmental conditionsshouldbesuitableforinstalling Table 4: with sand/cementscreed. Concrete, orconcrete Deck material Insulation material polyisocyanurate (PIR). – polyurethane(PU)and (RUF) boards Rigid urethanefoam composite products. slabs, perliteboardsor boards, cellularglass fibre orglass Compressed cork,rock „ „ „ „ „ „ „ „ „ installed onblacksheathingfelt to BS6925,type988 T25, 20mmthickontheflat and needed toretaintheinsulationmaterial be designedtosupporttheloads,particularlyfromballast not beusedforslopesgreaterthan10° control layer, insulationandsurfacefinish installed bythesamecontractorwhoinstallsvapour manufacturer, whereaproprietarysystemisused installed byaspecialistroofingcontractorapprovedthe recommendations manufacturer’s installed inaccordancewiththedesignand surfaces orwhenanyrain,sleetsnowisfalling. Membranes shouldnotbeinstalledondamporfrosted recommendations shouldbefollowed. not beinstalledbelow10°C,andthemanufacturer’s Self-adhesive reinforcedbitumenmembranesshould agreed withthemanufacturer). when theairtemperatureis5°Corless(unlessotherwise Sheet membranesshouldnotbeinstalledorhandled Reinforced bitumenmembraneforaninvertedwarmroof Reinforced bitumenmembraneusedinwarmroofconstruction First/preparatory layer produce partialbonding). (loose laidandlapped,to Type 3Gperforatedlayer BS 8217). accordance with S2P3 (fullybondedin produce partialbonding). (loose laidandlapped,to Type 3Gperforatedlayer First/preparatory layer

achieving S2P3 Elastomeric underlay S2P3 Second layer/underlay Second layer/underlay achieving S2P3 Elastomeric underlay S2P3 achieving S2P3 Elastomeric underlay S2P3

„ „ „ „ „ „ „ „ „ „ „ „ and 2x10mmlayersonvertical surfaces,forgreenroofs. (for greenroofs)3x10mmlayers onhorizontalsurfaces rounded pebbles. using pavingslabsorminimum19mmdiameter be ballasted be ballastedtothedepthspecifiedindesign installed sothatsuccessivelayersdonottrapwater. impede drainage installed sothatmembranelapsnearoutletsdonot and beforeinclementweather insulation boardsarewaterproofedattheendofeachday, checked bythecontractortoensurethatdeckand Flat roofs andbalconies mineral surfacedwhereexposed. Elastomeric capsheetachievingS2P3, separate solarprotection. S5P5 witheitherintegralmineralfinishor Final layer/capsheet Final layer/capsheet mineral surfacedwhereexposed. Elastomeric capsheetachievingS2P3, separate solarprotection. S5P5 witheitherintegralmineralfinishor mineral surfacedwhereexposed. Elastomeric capsheetachievingS2P3, separate solarprotection. S5P5 witheitherintegralmineralfinishor ballas t 7.1 CHAPTER filter layer plasterboar plaster or concrete dec screed tofalls waterproofing insulation

d 2020 k

6 6 7.1

. (3) . . (2) (2)

TPO (thermoplastic polyolefine) polyolefine) TPO (thermoplastic of paving. 2 Proprietary timber decking systems with bearers Proprietary timber decking systems with set on an additional membrane or suitable with Proprietary surface treatments compatible the membrane product. Proprietary flexible, non-slip walkway tiles, compatible with the membrane product. on Precast concrete proprietary paving slabs supports on a suitable non-woven polymeric protection layer. bearers Proprietary timber decking systems with set on additional pads on a suitable non-woven polymeric protection layer. Precast semi-porous concrete tiles bedded in Precast semi-porous adhesive. bitumen or approved on Precast concrete proprietary paving slabs supports or sand/cement blinding Proprietary timber decking systems in Precast semi-porous concrete tiles bedded bitumen or approved adhesive. on Precast concrete proprietary paving slabs supports or sand/cement blinding or Proprietary flexible, non-slip walkway sheets tiles, compatible with the membrane product. on Precast concrete proprietary paving slabs adjustable supports or suitable non-woven polymeric protection layer. non-woven polymeric protection layer. „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ Access roof, walkway or terrace deck Access roof, walkway

include waterproofing suitable for use in the green roof system. welded at laps using either hot air or a specific solvent welded at laps using Requirement R3. Technical with assessed in accordance „ „ „

„ „ „ d discharged into gutters and drain pipes. Chippings should be a minimum of

, bedded in a , bedded in a bitumen 2020 (1) (1)

dressing compound. based compound. with a suitable thickness of washed, rounded with a suitable thickness of washed, rounded 20-40mm shingle installed on a non-woven polymeric protection layer. Use in inverted/buried roof membrane applications or in roof garden/green roofs. sheet. Must be protected with a substantial reinforced bitumen membrane protection membrane to be applied All upstands/details where the membrane becomes exposed need a protective to prevent UV degradation. A solar reflective paint approved by the MAC. A or other Supplementary solar reflective coatings finishes not required. Where laid loose, membranes can be ballasted Products generally do not require supplementary solar reflective coatings or other finishes. Mineral surfaced capsheets (e.g. type S5P5). Mineral surfaced capsheets Reflective stone chippings suitable thickness of washed, rounded 20-40mm A shingle ballast laid loose. Reflective stone chippings „ „ „ „ „ „ „ „ „ „ „ Access for maintenance only – roofs up to 10° Access for maintenance „ „ „ „ „ „ „ „ „ „ „ Surface treatments for flat roofs Surface treatments CHAPTER 7.1 Flat roofs and balconies and roofs Flat

Green and proprietary roofs and proprietary Green

Timber decking systems should only use compatible preservative treatments. The undersides of the bearers should have large, smooth contact areas, with no The undersides of the bearers should have decking systems should only use compatible preservative treatments. Timber sharp edges or corners. Slabs should be kept back 75mm at perimeters and a 25mm movement gap incorporated for every 9m 12.5mm limestone or white spar, not pea gravel. 12.5mm limestone or white spar, Cement/sand blinding should be installed on two layers of waterproof building paper or two layers of 1000 gauge polyethylene separating membrane. Loose surface finishes should be prevented from being removed by weather an be clearly defined by the supplier as a complete system have supporting data to demonstrate compliance with relevant standards either bonded to the insulation, mechanically fixed to the either bonded to the sealed and ballasted in accordance deck or loose-laid, and with the manufacturer’s recommendations „ „ „ Hot melt rubberised bitumen systems Cold applied liquid roofing membranes Mastic asphalt Thermoplastic single-ply membranes Reinforced bitumen Reinforced bitumen membranes 3 Green roofs and proprietary roofing systems shall be suitable for their intended use. Green roofs and proprietary roofing systems shall be suitable for Green roofs should: 2 7.1.9 Notes 1 should be: 5: Table Surface treatments Surface treatments 5. Table should be in accordance with Surface treatments Thermoplastic single-ply membranes single-ply Thermoplastic and (polyvinyl chloride) such as PVC including materials single-ply membranes, Thermoplastic Rainwater outlets should be accessible and have a visible inspection hatch. be assessed in accordance with Green roof systems that do not comply with the principles of this chapter should Requirement R3. Technical „ „ „ 7

7 7.1 The system should be installed in accordance with the design and the membrane manufacturer’s recommendations. The systemshouldbeinstalledinaccordancewiththedesignandmembranemanufacturer’s „ „ „ „ „ Other issuesthatshouldbetakenintoaccountwheninstallinggreenroofsincludethe: Before covering: Table 6: Waterproofing forgreenroofsshouldbeeither: The completegreenroofshouldbeinstalledbyacontractortrainedandapprovedthesystemsupplier. Features Drainage falls Structure layer Vapour control Moisture control filter layers Protection and Roots Insulation „ „ „ „ „ height ofupstandsinrelationtosoilandflashings provision ofrootbarriers results shouldbemadeavailabletoNHBC rectified, andretestedbeforefurtherlayersareplaced:the electronically testedforwaterproofingintegrity, faults the membraneshouldbevisuallyinspectedand mastic asphalt reinforced bitumenmembrane Principles forgreenroofs „ „ „ „ „ „ „ „ „ „ „ „ „ Intensive „ „ „ „ „ „ „ „ „ „ „ „ „ Can bedesignedtoretainsomewaterinordermaintain the vegetationandtoreducerunoff. Irrigation systemmayberequired. 1:60min. concrete deck). weight ofwetsoil(generallysupportedbya 20° maximumroofpitch,accountingforfull weeding/planting. maintenance ofthegarden,e.g.from membrane frompossibledamageduring Requires protectionofthewaterproofing i.e. similartoanormalgarden. Requires regular‘intensive’ maintenance, ‘normal’ plants. Uses naturaltopsoil150mmdeepand Provides anormalgardenenvironment. reservoir layer. A filterlayershouldbeplacedabovethe above thewaterproofingmembrane. A protectionlayer(orboard)shouldbeplaced used. waterproofing membrane. Alternatively, anapprovedrootresistantwaterproofing membranecanbe A rootresistantelement,suchasacopperfoilorPreventoltreatment,isrequiredabovethe Where theinsulationisaboveweatherproofing,onlyextruded polystyrene(XPS)shouldbeused. Insulation materialshouldhaveadequatecompressivestrength towithstandlikelyappliedloads. membrane. Fully bondedpolyester-reinforcedRBM(S2P3),asuitable self-adhesive membraneortorch-on soil andvegetation drainage/reservoir layer filter layer waterproofing root barrier protection layer ceiling finis concrete deck screed tofalls vapour controllayer insulation

h „ „ „ „ „

„ „ „ „ „

moisture controlofthesoil. protection, reservoirandfilterlayers using afullwidthsectionofmembrane. any damagetothevapourcontrollayershouldberepaired, a liquidappliedsystem. single-ply membrane,or Flat roofs andbalconies „ „ „ Extensive „ „ „ „ „ depending onloadings). decks maybeanalternativetoconcrete, 45° maximumroofpitchdeck(profiledmetal A sedumblanketcontainstheplants. i.e. annualattention. Requires minimalmaintenance, manufacturer’s recommendations. manufacturer’s In accordancewiththe growing medium sedum blanketand 7.1 CHAPTER

waterproofing root barrier filter layer ceiling finis on loading deck, depending profiled metal concrete deckor screed tofalls vapour controllayer insulation

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8 8 7.1 e n

n n waterproof membra vapour control layer insulation waterproof membrane insulatio screed concrete deck

metal flashing waterproof membrane insulatio surface treatment vapour barrier screed concrete deck surface treatment (where required) m surface treatment (where required) d min. 150m OSB or plywood layboar vapour control layer min. 150mm battens, tiles/slates tilting fillet preformed kerb Handrail fixing roofs. An upstand should be formed in concrete Pitched roof abutment Skirting to rooflights or ventilator kerb Skirting to rooflights to inverted roofs. Similar details apply ballast to achieve a minimum Allow for thickness of 150mm upstand. 2020

k n r

) waterproof membrane insulatio screed concrete deck metal flashing battens, tiles/slates insulation waterproof membrane insulation vapour control layer concrete dec t

waterproof membrane vapour control layer surface treatment (where required screed to upstand and over expansion join mineral surfaced top laye min. 150mm

y upstand OSB or plywood capping capping fixed to one kerb onl OSB or plywood Preformed coping (e.g.GRP) surface treatment (where required) Detailing of flat roofs flat of Detailing

CHAPTER 7.1 Flat roofs and balconies and roofs Flat

Mansard edge Elements should be firmly fixed to prevent peelback Timber decks Timber in high winds. Similar details apply to inverted roofs. Twin-kerb expansion joint Twin-kerb Upstands may be fixed to the wall. Upstands may be fixed a minimum of 150mm high. Upstands should be to inverted roofs with concrete decks. Similar details apply Concrete decks Upstands The following illustrations are intended as a guide to demonstrate the general principles of flat roof detailing commonly used the general principles of flat roof are intended as a guide to demonstrate The following illustrations roof construction. Further are applicable to other types of and balconies. Where indicated, the principles on warm flat roofs from BS 6229 and BS 8217. waterproofing systems may be obtained information on specific 7.1.10 performance. to ensure satisfactory shall be detailed Flat roofs 9

9 7.1 upstand dimensions. the thicknessofballastininvertedroofs,toachieve Similar detailsapplytocoldandinvertedroofs. Allow for Upstand toventilatororrooflightkerb being liftedbywindsuctionandanalternativedetailused. Inverted timberdecksshouldbedetailedtoavoidinsulation Welted driptoexternalgutter Similar detailsapplytocolddecktimberroofs. for movement.Upstandshouldbeaminimumof150mmhigh. Upstand shouldbekeptseparatefromwall,andallow Independent skirtingdetail 300mm timber kerb top layerto min. surfaced (where required) surface treatment mineral face of tray cavity 50mm triangular fille 50 x50mm board insulatio upstand of flashin metal cover 150m min. g t n m 150mm min. timber deck (where required surface treatment vapour controllayer insulation waterproof membrane vapour controllayer insulation waterproof membrane vapour controllayer insulatio waterproof membrane ) n

Detailing ofupstandandflashingissimilarforallroofs. Vapour controllayershouldbebondedtothewaterproofing. Pipe passingthroughroof Similar detailsapplytoinverteddecks. Verge detail Similar detailsapplytoconcreteroofs. displacement bythermalexpansionofrainwaterpipe. Ensure thattheoutletisfixedsecurelytodeckingprevent The outletshouldbeatthelowestpointinroof. The openingshouldbeproperlytrimmed. Rainwater outlet Flat roofs andbalconies (where required) surface treatment 150mm (where required) surface treatment min. membrane waterproo f and outlet insulation aroundpipe 7.1 CHAPTER over insulation layer turnedback vapour control sleeve aroundpip apron flashingbondedtopipe insulation aroundpipe vapour controllayer insulatio waterproof membrane vapour controllayer insulation built uptimberkerb edge trim n

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alternative hoppe discharge low kerb min. 25mm below underside of the door sill to act as overflow d rainwater outlet hopper (should not pass through accommodation below) balustrading

overflow/warning pipe outlet min. 25mm below the underside of the door sill cantilevere balcony f fall

rainwater outlet position of waterproofing layer for a warm deck balcony/roo

min. 150mm splash zone min. 150mm splash zone have a minimum 45mm projecting sill to shed rainwater have a minimum 45mm with the waterproofing layer away from the interface balcony upstand below the have a 75mm minimum sill, measured from the balcony underside of the projecting drainage layer. fall „ „ fall „ „ position of drainage layer or for an inverted balcony/roof raised and drained decking or paving on drained supports

d

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raised and drained decking or paving on drained supports

balcony/roof waterproofing layer for an inverte position of waterproofing layer with falls to outlet

75mm min. upstand

75mm min. upstand

min. 10mm supporting slab min. 10mm supporting slab projecting sill and drip (min. 45mm overhang) (min. 45mm overhang) projecting sill and drip finished floor level finished floor level Accessible thresholds Accessible CHAPTER 7.1 Flat roofs and balconies and roofs Flat

3D 3D

have a maximum 15mm upstand (measured at the door have a maximum 15mm threshold; additional sloping transition position) at the door small internal ramp and external sill, elements, such as a side of the upstand; may be provided either be in accordance with the design – specific fire, be in accordance with precautions may be required thermal and acoustic on ramps and sills should be 15 the maximum slope degrees „ „ Note roof should be considered as the drainage layer). The drainage layer is not necessarily the waterproofing layer (i.e. the top of the insulation of an inverted Accessible thresholds should: Accessible thresholds 7.1.11 drainage. and by adequate weatherproofing be protected thresholds shall Accessible „ „ 11

11 7.1 A splashbarriershouldbeprovided: „ „ „ „ „ „ „ „ „ „ „ „ „ To ensureadequatedrainage: Outlets beneathdeckingorpavingshouldbeclearlyidentifiableandaccessibleformaintenance. downpipe isblocked. This canbeachievedbyusing: Drainage arrangementsshouldbeeffective andhaveasuitableoverflow. Thebuildingshouldnotfloodwhereanoutletor and designthatpreventsabuild-up ofstandingwater. and islessthan150mmbelow thesill,itshouldbeofatype Where deckingorpavingisinstalled abovethewaterproofing Open slattedbalconydeckingshoulddrainawayfromthehome. of waterdischargingfrommultiplebalconiesinverticalalignmentshouldbetakenintoaccount. staining toafaçade,ordamagelandscaping,thenrainwaterguttersanddownpipesshouldbeprovided. The cumulativeeffect Flat roofsandbalconiesshould: Falls Rainwater disposalfromroofsandbalconies6m The principlesfordrainagegiveninChapter7.2‘Pitchedroofs’ a) falls be takenintoaccountinclude: Flat roofsandbalconiesshallhaveadequateeffectiverainwaterdrainagetoasuitableoutfall. Issuesto 7.1.12 Waterproofing layersshould: „ „ „ „ „ „ „ „ „ „ „ „ „ are achievedusingscreeds(particularly onlargeroofs). account fordeflectioninthestructuraldesignwherefalls unless ithasametalsheetcovering have aminimumfinishedfallof1:80(greenroofs1:60), used asjustification analysis whichincludesoverallandlocaldeflectionis a finishedfallofnolessthan1:80,unlessdetailed be designedwithafallnoshallowerthan1:40toensure to aminimumof150mmabovethedeckingorpaving could beadverselyaffected bythepresenceofmoisture to ensurewaterdoesnotreachanypartofthewallthat perimeter wallsandkerbs individual unitsofdeckingorpavingandthethresholdsill, minimum 10mmgapsshouldbeprovidedbetween balcony perimeters gaps shouldbeprovidedbetweendeckingandpavingat discharge andoverflowcapacities) at least one outlet chute and hopper (sized to serve both the the outlet at leastoneoutletandanoverflowwiththecapacityof cause floodingtothebuilding parallel tothebuilding,blockageofoutlet(s)cannot be designedtoensurethatwherefallsaretowardsor zero degrees be subjecttospecificthird-partyassessmentwherefallsare the rainwateroutlet(s) generally fallaminimumof1:80awayfromthebuildingto prevent pondingandassociatedstagnantwater Drainage

2 orlessinareashouldbeconsidered.Whererun-off maycausedamageor

areapplicabletoflatroofsandbalconies. „ „ „ „ „ „ „ b) „ „ „ „ „ „ „ not obstructtheflowofrainwatertooutlet(s). spacers andsupportswhichraisedeckingorpavingshould door threshold. setting thebalconykerbaminimumof25mmbelow two outletsconnectedtoindependentdownpipes,or be UVresistantorfullyprotectedfromdaylight. decking orpaving be capableofwithstandingpointloadsfromsupportsto be fullyprotectedfromdirecttrafficking and cavitytrays. waterproofing layertoformanupstandwithcoverflashings using animperviouswallfinishorcladding,extendingthe outlets. Flat roofs andbalconies fall awayfromdoor 150m min. fall m (for designpurposes) fall nolessthan1:40 7.1 CHAPTER outlet the deck) 50mm from (invert min. overflow

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12 12 7.1

Minimum depth (mm) 38 50 of higher capacity than the combined capacity of the be recessed to facilitate the free flow of water be accessible for maintenance. other outlet(s). it should be installed directly onto the vapour control layer, layer, the vapour control installed directly onto it should be above waterproofing with the primary formed with mitred joints cross falls should be should be installed with a minimum successive roof layers avoid trapping water during construction. to of delay, 7 where a cement/sand Table to the minimum thickness in screed, 1:4 (cement:sand) is used suitably dry and primed to receive the waterproofing system. „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ Nominal thickness (mm) 40 (25 minimum.) 70 (50 minimum.)

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Minimum width (mm) 38 38

Size of firring pieces used to form cross falls Minimum screed thicknesses CHAPTER 7.1 Flat roofs and balconies and roofs Flat

the building sized and positioned to prevent water from entering provided through parapet walls or perimeter upstands be of the size and number required to deal with the expected rainfall intensity in accordance with BS EN 12056-3 used to form falls, unless the design specifies a sloping used to form falls, unless the design specifies joist or ceiling installed across the 8 where Table of the sizes given in joists. finished with a wooden float to provide a smooth, even finished with a wooden float to provide waterproof finish surface for the vapour control layer and a lightweight installed by specialist contractors where (cement:sand), finish is used, and have a topping of 1:6 13mm thick free from ridges and indentations construction should comply with the design and construction should manufacturer’s recommendations should ensure that boards are the sequence of installation roof sealed at the end of each day, waterproofed and the of inclement weather or before the arrival drainage should be designed by the insulation be designed drainage should less than 1:60 with falls of no manufacturer, „ „ „ „ „ „ „ „ „ „ „ Joist centres (mm) 400 or 450 600 Location of screed concrete Bonded monolithically to in-situ or precast Unbonded (on separating layer) Rainwater outlets Rainwater outlets should: less than 1:60. 8: Table Timber roofs Timber Firring pieces should be: Table 7: Table Concrete roofs finishes should be: set to achieve the falls. Screed be finished with sand/cement screed topping Concrete roofs can Flat roofs with metal sheet roof coverings should be designed with a fall of no less than 1:30 to ensure a finished fall of no with a fall of no less than 1:30 to ensure sheet roof coverings should be designed Flat roofs with metal Metal sheet roofs Where tapered insulation is used: Where tapered Where a flat roof or balcony has an upstand on all sides, drainage should consist of either two outlets or one outlet plus an Where a flat roof or balcony has an upstand on all sides, drainage should consist The overflow should be: overflow. „ „ „ „ „ „ „ „ „ „ „ 13

13 7.1 „ „ „ Provision shouldbemadeforsafefutureaccesstoflatroofsthepurposesofmaintenance. Access formaintenance Balustrading andguardrailsshouldbeofadequatedurabilityfixedsecurely Durability andfixingofbalustradingguardrails Masonry balconywallsshouldbebuiltinaccordancewithChapter6.1‘Externalmasonrywalls’.Inparticular: Strength andmovementofmasonrybalconywalls incorporate aringbeamorothersupporttoensurestability. create aslipplanethatcanseriouslylimittheabilityofwalltoresisthorizontalforces.Insuchcases,itmaybenecessary to In balconywalls(especiallylongbalconies)thestructuralstabilityshouldbechecked,asDPCatbaseofwall can ensure stability. balustrading fixedtoparapetwallsensurestabilityandpreventoverturning.Endfixingsorreturnsmaybeneeded to resisthorizontalloadingandasrequiredbythebuildingregulations.Particularcareisneededwhendesignincorporates Guarding, includingparapetwalls,andbalustradingusedasguarding,shouldbedesignedinaccordancewithBSEN1991-1-1 Stability ofguarding Guarding should: Guarding c) b) a) guarding adequately guardedtominimisetheriskoffalling.Issuesbetakenintoaccountinclude: Balconies, andflatroofstowhichpersonshaveregularaccessotherthanformaintenance,shallbe 7.1.13 „ „ „ the design walls shouldincorporatestrengtheningasrequiredby be toanadequateheight not beeasilyclimbed strength andmovementofmasonrybalconywalls stability ofguarding Guarding to balconies

„ „ „ „ e) d) „ „ „ „ precautions aretaken. not befixedthroughthewaterproofingunlesssuitable glazed balustradingisused be toughenedglass,laminatedglassorblockswhere copings shouldbefirmlyfixed. the design movement jointsshouldbeprovidedinaccordancewith access formaintenance. durability andfixingofbalustradingguardrails Flat roofs andbalconies . Also seeClause7.1.4(a). 7.1 CHAPTER Also see:Chapter6.1

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14 14 7.1 Pitched roofs CHAPTER 7. 2 This chapter gives guidance on meeting the Technical Requirements for pitched roofs, including: „„coverings „„vertical tiling „„fixings „„ventilation „„weatherproofing.

7.2.1 Compliance 01 7.2.2 Provision of information 01 7.2.3 Design of pitched roofs 01 7.2.4 Protection of trusses 03 7.2.5 Durability 04 7.2.6 Wall plates 04 7.2.7 Joints and connections 05 7.2.8 Restraint 06 7.2.9 Bracing for trussed rafter roofs 07 7.2.10 Strutting for attic trusses and cut roofs that form a floor 09 7.2.11 Support for equipment 09 7.2.12 Access 09 7.2.13 Dormer construction 09 7.2.14 Underlay and sarking 10 7.2.15 Ventilation, vapour control and insulation 11 7.2.16 Firestopping and cavity barriers 13 7.2.17 Battens 14 7.2.18 Roof coverings 14 7.2.19 Fixing tiles and slates 15 7.2.20 Weathering details 18 7.2.21 Valleys and hidden gutters 20 7.2.22 Drainage 21 7.2.23 Fascias and trim 21 7.2.24 Spandrel panels 22

Also see: Chapter 2.1 Also see: traditional cut roofs. the designer should provide details of the complete roof (particular care is needed in such circumstances). trussed rafters support traditional cut roof members, or it is a proprietary system (designs supplied by manufacturers will generally be acceptable). size and approximate position of water tanks or other size and approximate position of water equipment to be supported and positions and dimensions of hatches, chimneys type of preservative treatment, where required match special timber sizes, where required to existing construction. ensure stability with the complete structure, including the connections and compatibility with the supporting structure and adjacent elements where trussed rafters and a cut roof are combined, Details of restraint/holding-down strapping, Details of restraint/holding-down including coatings and fixings. The position and thickness of insulation. The means of providing eaves ventilation. and boxed eaves. Details of firestopping at separating wall number Details of coverings and fixings, including and type. chimneys, etc. Details of flashing details at abutments, hatches, etc. Details of trimming around chimneys, access other openings „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ b) „ „ „ „ „ „ „ „ „ „ „ „ „ „ „

Also see: TRADA Eurocode 5 span tables (3rd edition) and BS 8103-3 Eurocode 5 span Also see: TRADA

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7.2 CHAPTER Pitched roofs Pitched

trussed rafter roofs the spans, sizes, spacing or strength classes of the timber are outside the scope of authoritative tables the roof is not a basic pitched roof hips, valleys or other special features are included in a trussed rafter roof ensure that the structure is coherent and that all forces be appropriate for the location, accounting for exposure and wind uplift have dead and imposed loads calculated in accordance with BS EN 1991-1-1, BS EN 1991-1-3 and BS EN 1991-1-4 be in accordance with PD 6693-1, and Requirement R5, where appropriate Technical are resolved eaves overhang and other eaves details eaves overhang and other eaves details method of support and position of supports method of support and position of supports sarking, insulation type and weight of coverings, including and ceiling materials rafter profile, referencing camber where required rafter profile, referencing camber where spacing, span and pitches The type and position of vapour control layers. The type and position of vapour control any usage, height and location of building, referencing unusual wind conditions Details of bracing requirements. roof space. Details of supports for equipment in the Details of girder trusses, multiple trusses and diminishing Details of girder trusses, multiple trusses together and trusses, including how they are to be fixed similar. supported on truss shoes, layboards or The layout of trusses and associated items. The layout of trusses roof intersections Details of mono-pitch, lean-to roofs and (i.e. hips and valleys). „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ a) The sizing and spacing of members shall ensure structural stability and provide restraint to the structure The sizing and spacing of members shall ensure structural stability include: without undue movement or distortion. Issues to be taken into account Design of pitched roofs pitched of Design 7.2.3 Designs and specifications should be issued to site supervisors, relevant specialist subcontractors and suppliers, relevant specialist subcontractors should be issued to site supervisors, Designs and specifications information: and include the following Provision of information of Provision 7.2.2 include all relevant a clearly understandable format, shall be produced in Designs and specifications personnel. be distributed to the appropriate information and Pitched roofs that comply with the guidance in this chapter will generally be acceptable. with the guidance in this chapter Pitched roofs that comply with BS 5534. covering should be in accordance Roofs with a tile or slate Compliance 7.2.1 Requirements. Technical comply with the coverings shall roof structures and Pitched Roofs should be designed by an engineer in accordance with Technical Requirement R5 where: Requirement Technical Roofs should be designed by an engineer in accordance with For trusses, the design should be provided to the manufacturer in accordance with PD 6693-1, which includes: For trusses, the design should be provided „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ The design of pitched roofs should: 1

1 7. 2 „ „ „ „ „ „ „ „ „ „ „ trussed raftersareused,theyshouldbe: Where multipleandreinforcingtimberstosimpleor increased toamaximumoftwicethenominalspacing,providedthatspacingXislessthan,orequalto,2A-Bwhere: Where themaximum600mmspacingcannotbeachieved,e.g.toaccommodatehatchopeningsorchimneys,may roofing tilebattens. Where thewidthofagableladderexceedsthattrussed raftercentres,noggingsshouldbeusedtoreducethespanof accordance with Technical RequirementR5. accordance with Table 1,unlessdesignedbyanengineerin The bearingofmono-pitchedtrussesintoshoesshouldbein girder truss. a seriesofdiminishingmono-pitchedtrussessupportedby Hipped roofsconstructedwithtrussedrafterstypicallyrequire Plasterboard shouldbefixedasfollows: Ceiling finishesshouldbefixedaccordingtothespacingofsupportmembersandthicknesssheet. Table 1: Trussed raftersshouldbe: Trussed rafterroofs C24 or TR26. WhenusingtheBS4978gradingrules: Structural timbershouldbeofasuitablegradeandspecifiedaccordingtothestrengthclassesinBSEN338,e.g.C16, For traditionalcutroofs: Traditional cutroofs 4m ormore Less than4m Span „ „ „ „ „ „ „ „ „ „ „ simple triangle where necessary, particularlywhere theroofisnota members shouldbefullysupported andtiedtogether members accuratelylocated the roofshouldbeinaccordance withthedesignand member andthemethodoffixing orjointing the designshouldspecify detailsofeachstructural support spacingof600mm 12.5-15mm plasterboardshouldbefixedatamaximum spacing of450mm 9.5mm plasterboardshouldbefixedatamaximumsupport should besupplied. drawings andspecificationsshowingthefixingmethod either fixedtogetherduringmanufacture,orfullydetailed designed tobepermanentlyfastenedtogether and theadjacenttrussedrafter X =distancebetweencentresoftrussedtrimmedrafters double skewnailingortrussclips) fixed tothewallinaccordancewithdesign(e.g.using the designer spacing shouldnotbealteredwithoutpriorconsentfrom installed inaccordancewiththedesign,andstructureor class identified BS EN1912,orthetimberspeciesandstrength the timberspecificationshouldbeinaccordancewith Bearing lengthofmono-pitchedtrussesintoshoes 75mm 50mm Minimum bearinglength

„ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ B =nominalwidthofopening. A =designspacingoftrussedrafters evenly spacedatmaximum600mmcentres. and tokeeptrussesvertical) temporary bracingshouldbeusedtomaintainspacing vertical andsuitablylocated(wherenecessary, the timbershouldbemarkedaccordingly. framing shouldbecompleted before coveringsareinstalled. purlins andbindersshouldbe builtinwherenecessary until framingiscomplete temporary supporttolongspan membersshouldbeused further apart. coverings andfinisheswheretrussesarespaced Additional memberswillgenerallyberequiredtosupport A X B X 35mm 35mm Minimum thicknessoftrussedrafter trussed trimmedrafters Pitched roofs A CHAPTER 7.2

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2 2 7. 2

n fness. pole plate spanning betwee load-bearing walls

To avoid distortion and to To valley rafter hip rafter jack rafter stored with level bearers under the joints carried upright (fasteners can loosen when carried flat). stored vertically and propped „ „ „ „ „ „ Also see: International Truss Plate Association Technical Handbook Association Technical Plate Also see: International Truss

r ridge colla strut wall load-bearing be provided with intermediate support where required. be provided with intermediate cut of the jack rafters. than the other rafters to take the top have a deeper section spreading outwards stop the walls and roof ceiling finish and walkways, etc. provide support to the be larger than ordinary rafters to take the additional load be larger than ordinary for the splay cut of jack rafters provide full bearing „ „ „ „ „ „ Provides spacing and fixing for jack rafters and should: Provides spacing and of the hip rafter. at hips and lip cut to accept the bottom Purlins should be mitred the rafters and should: Provides support for spacing for the tops of the rafters. Provides fixings and and increase stif long span rafters to prevent deflection Provides support to Notes roof and should: both sections of the for loads from Provides support „ „ „ „ „ „ Provides support to purlins to prevent deflection and to transfer roof loads to the load-bearing Provides support to purlins to prevent deflection structure below. the roof together at purlin level. Ties Provides support to long span ceiling joists. joists are above wall plate level. Similar to purlins, but used where ceiling Minimum size 100mm x 50mm 32mm thick Rafter cut + 25mm 2020

Typical sizes for timber members Typical Basic timber members Basic timber purlin binder hanger 7.2 CHAPTER Pitched roofs Pitched

wall plate

adequately ventilated during storage stored clear of the ground protected against weather to prevent the corrosion of truss plates and the deterioration of the timber „ „ „ Hip rafter Ceiling joist or ties Ridge Purlin Member Struts Valleys Ridges and hips Valley rafter Valley Member Struts Collar Ceiling binders and hangers Pole plates Trusses shall be protected from damage. Trusses not repaired. Where the trusses or timber members are damaged, they should be rejected and Protection of trusses of Protection 7.2.4 Table 3: Table Generally sizes should be as Table 3, unless designed by an Table Generally sizes should be as Requirement R5. Technical engineer in accordance with prevent damage, trusses should be: Table 2: Table „ „ „ 3

3 7. 2 „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ naturally durableorsuitablytreated: Where theroofistoincludeafullysupportedweatherproofingmembrane,followingtimbercomponentsshouldeitherbe Fixings forstrapsshouldbe: should beused.Holding-downstrapsbe: Where theroofisrequiredtoresistuplift,skewnailingunlikelyprovidesufficientstrength,andappropriatemetal straps one oneachsideofthetrussedrafter, instructions)areacceptable. ortrussclips(fixedinaccordancewiththemanufacturer’s Where trussedrafterroofsarenotsubjecttouplift,aminimumoftwo4.5mmx100mmgalvanizedroundwirenails,skew nailed, the site. Fixings usedtoconnecttheroofstructurewallplateshouldbespecifiedaccordingconstructionand exposureof Wall plates should be: unless specificallydesignedotherwise,e.g.asacantilever. supported atthejunctionbetweenceilingtieandrafter, supported ontimberwallplates. Trussed raftersshouldonlybe Trussed rafter roofsandtraditionalcutshouldbe prevent uplift. Wall platesandtheroofstructureshallbebeddedfixedtodistributetransmitloads, 7.2.6 Wall plates (natural solidtimber)’: The followingtimbermembersshouldbenaturallydurableortreatedinaccordancewithChapter3.3‘T Timber shallbeofsuitabledurability. 7.2.5 Durability „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ of amaterialorfinishwhichiscompatiblewiththestraps be within150mmofthebottomverticalstrap in accordancewiththedesign,andlowestfixingshould provided inaccordancewiththedesign against uplift provided wheretheself-weightofroofisinsufficient construction type provided accordingtothegeographicallocationand 38 x100mmorinaccordancewithlocalpractice. joined usinghalf-lappedjoints,includingatcorners rafters ortrusses a minimumof3morextendoveratleastthreejoists, fixed usingnailsorstraps bedded tolineandlevel Bracing. Ceiling joists. Purlins. Rafters. Soffits. Tiling battens. Porch posts.

„ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ Battens forfixingverticalcladding. Wall plates. Sarking. Fascias andothertrim. Bargeboard. long No12woodscrews(intosuitableplugs). where intomasonry, hardened4mmx75mmnailsor50mm fixed tothewall,orturnedintoabedjoint. generally acceptable) at amaximumof2mcentres(galvanisedsteelstrapsare a minimumcrosssectionof30mmx2.5mmandspaced w 50mm or¹⁄ʥxS max. projection= hichever islarger S Pitched roofs CHAPTER 7.2 imber Preservation rafter ceiling ti

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e

4 4 7. 2

e g g tie prevents wall plates spreadin timber angle dragon ti prevents spread of hip rafter steel tie prevents spread of hip rafter plywood angle tie prevents wall plates spreadin scarf joint near strut supporting longer span of purlin wedges and metal plate to tighten joint d ¹⁄ʥd not be damaged or split. not be damaged or „ Rafter to purlin generally the purlin is birdsmouth joint should be used A fixed vertically. Scarf joint Used to support the long span of the purlin. „

e e over strut halving joint in purlin when directly angle ti notch to fit over angle ti e 2020

rafters skew nailed to wall plat 7.2 CHAPTER Pitched roofs Pitched

be accurately cut to fit tightly be accurately cut to „ they should be jointed using dragon ties, or similar, to prevent they should be jointed using dragon ties, or similar, the hip rafter spreading. Hipped roof joints Angle ties should be used at the corners of hipped roofs to prevent the wall plates from spreading. Where hip rafters are heavily loaded, e.g. carrying purlins, Support should be provided directly under the joint or a scarf Support should be provided directly under near to a strut so that joint used. Scarf joints should be made the joint supports the longer span. Purlin connections The rafter should be birdsmouthed and skew nailed to the The rafter should be wall plate. Rafters to ceiling joists using a nailed lapped joint Rafters to ceiling Members should: Joints and connections and Joints 7.2.7 or undue movement stability without to ensure structural be designed connections shall Joints and distortion. „ The following joints should be used at the main connections of traditional cut roof members: should be used at the main connections The following joints 5

5 7. 2 „ „ „ „ „ „ „ Lateral restraintstrapsshouldbefixedtotheroofstructurebyeither: Proprietary strapsshouldbe: Gable ladderscanbeusedtoproviderestrainttheexternal wallwhere: shows otherwise. construction. Wherepurlinsareusedtoproviderestraint,the maximumpermissiblespacingis2munlessthedesign In framedroofs,asanalternative,purlinsandpoleplatescan beusedtoproviderestraintwherethetimberabutsagable Lateral restraintstrapsshouldbe: Figure 1 Lateral restraintstrapsshouldbelocated: installed inaccordancewiththedesign. Restraint straps,orarestrainingformofgableladder, shouldbeusedwhererequiredtoprovidestabilitywalls,and Strapping shallbeofadequatestrengthanddurability, andfixedusingappropriatefixings. Adequate restraintshallbeprovidedtosupportthestructure,distributeroofloadsandpreventwinduplift. 7.2.8 Restraint „ „ „ „ „ „ „ In accordancewith Technical RequirementR3 inner leaf(maximum2mspacing) there isblockingbetweenthelasttrussedrafterand acceptable inNorthernIrelandandtheIsleofMan) Clause 6.1.11 Table 4(sherardisedstrapsorfixingsarenot protected againstcorrosioninaccordancewithBSEN845-1 require restraintatceilinglevel) of masonryconstruction(largerorseparatingwallsmay provided atrafterlevelongablewalls,wherethehomeis correct lengthandnumberofbendstwists ordered andsuppliedaccordingtothedesign,i.e. nails, withonefixinginthethirdrafter(Figure1),or 4mm steelscrewsorfour75mmx(8SWG)round fixing tosolidnoggingsusingaminimumoffour50mmx Scotland), atamaximumspacingof2m for homesuptoandincludingthreestoreys(twoin fixings (atleastoneinthethirdrafter) fixed withaminimumoffour strap underneathsolidnoggings, twisting therestraintstrap nogging fixedhorizontallytoavoid

strap heldtightly rafter andwall packing between for clarity block remove inner leaf against block d

„ „ „ „ „ „ „ „ strap underneaththe25x100m Figure 2 additional timbermember)fixe with aminimumofeightscrews „ „ „ „ „ „ „ „ strap doesnotcoincidewithalongitudinalbinder. with Clause7.2.9canbeusedwherethepositionof members, fixedoverfourtrussesandnailedinaccordance the strap(Figure2). Alternatively, 100mmx25mmtimber x 4mmsteelscrewsevenlydistributedalongthelengthof fixing tolongitudinalbracingmembersusingeight25mm of 1.25m. for homesfourstoreysorover, fixedatamaximumspacing recommendations. Installed inaccordancewithmanufacturer’s restrain theouterleaf. the soffitboardiscutcarefullyandthenfixedsecurelyto timber frameconstruction. in accordancewithBSEN1995-1-1,wherethehomeisof preferably fittedoverthecentreofanuncutblock fixed withthedownturnonasubstantialpieceofblockwork, anchorage downturnto100mm(orproprietarystraps) a minimumsizeof30mmx5mmandhave of sufficientlengthtobefixedaminimumthreetrusses longitudinal bracing(oran m d Pitched roofs inner leaf face ofblock tightly tointernal bracing fitted CHAPTER 7.2 strap heldtightlyagainstblockinnerleaf Also see:Chapter6.1

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6 6 7. 2 3 6.4 5.6 4.5 5.6 4.5

2 7.2 6.4 5.6 6.4 5.6 1 8.1 7.3 6.5 7.3 6.5 25° 3 5.1 4.4 3.7 4.4 3.7 2 5.8 5.0 4.4 5.0 4.4 1 6.6 5.8 5.1 5.8 5.1 30° 3 4.3 3.6 3.0 3.6 3.0 2 4.5 4.2 3.6 4.2 3.6 Also see: BS EN 1995-1-1 and PD 6693-1 BS EN 1995-1-1 and Also see: 1 5.6 4.9 4.3 4.9 4.3 Mono-pitch 35° 3 10.2 8.8 7.5 8.8 7.5 2 11.5 10.0 8.7 10.0 8.7 there should be a minimum of four diagonal rafter braces in each roof; in narrow fronted roofs and mono-pitched roofs, where the braces cross, the intersection detail (below) should be used. completed before the roof covering is laid 100mm x 25mm provided using a minimum timber size of (3mm tolerance) should be nailed twice to each rafter it crosses; fixings round wire nails 3.35mm x 65mm (10 gauge) galvanized they should where braces and binders are not continuous, be lap jointed and nailed to a minimum of two trusses. longitudinal bracing members should extend the full length of the roof, tightly abut gable and party walls and permit diagonal bracing to pass (they may be lap-jointed providing the overlap is nailed to a minimum of two trussed rafters) has trusses which are only supported at each end has trusses which are masonry spanning more does not have unsupported walls, piers or chimneys) than 9m (between buttressing directly under each truss has a ceiling of plasterboard i.e. garages, additional (where there is no plasterboard, binder bracing at diagonal ceiling bracing and longitudinal each ceiling node point is required. „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ 1 12 11.6 10.6 11.6 10.6 30° 3 8.5 7.2 6.0 7.2 6.0

2 9.1 7.7 7.2 7.7 7.2 s 1 10.6 9.8 8.6 9.8 8.6 Duo-pitch 35° binders fixed to ceiling ties of trussed rafters, where necessary using two lap-jointed length 2020

Storeys England and Wales Scotland Areas north or west of Ullapool Northern Ireland and the Isle of Man Areas north-east of Londonderry Type Maximum pitch Location, height and span for standard bracing conditions Location, height and span for standard binders abutted tightly against gable and separating walls 7.2 CHAPTER Pitched roofs Pitched

appropriate for the site (where the site is in an exposed appropriate for the site (where the site is for additional location, the design should be checked as specified requirements, and the bracing completed in accordance with this chapter or PD6693-1 in accordance with this chapter or PD6693-1 without prior in accordance with the design and not altered approval from the designer suitably fixed to the wall plate) diagonal and chevron bracing should pass across each small gaps, such as two trussed rafter in the roof, however, rafters between sets of bracing, or one trussed rafter adjacent to gable or separating walls, is permitted in the middle of an otherwise fully braced roof diagonal and longitudinal bracing should be provided at rafter level (this may be omitted where rigid sarking boards are used, e.g. chipboard, plywood or OSB, which are fixed to each trussed rafter with 3mm x 50mm galvanised round wire nails at 200mm spacing) is braced according to the conditions of the site and in is braced according accordance with the design than 12m does not have trusses which span more is not taller than 8.4m (to the underside of the ceiling tie) is not taller than 8.4m with this chapter is braced in accordance has a rectangular roof (including hip ends) and is either a has a rectangular roof structure duo-pitched or a mono-pitch „ „ „ „ „ „ „ „ „ „ Maximum span (m) Roof bracing should be: Applicable to all trussed rafter roofs unless rigid sarking, such as timber boarding or plywood, is used. Applicable to all trussed rafter roofs unless rigid sarking, such as timber boarding Diagonal rafter bracing should be approximately 45° to the rafters on plan. Diagonal rafter bracing When bracing pitched roofs: Table 4: Table For the purposes of this chapter, the guidance and use of standard trussed rafter bracing does not apply to homes on or near of standard trussed rafter bracing does the guidance and use this chapter, For the purposes of be designed by an engineer in moorland. In such cases, bracing should flat coastal fringes, fens, airfields and exposed sites, e.g. Requirement R5. Technical accordance with acceptable, where the home: 4, is generally Table bracing, in accordance with Standard trussed rafter Bracing for trussed rafter roofs rafter trussed for Bracing 7.2.9 undue movement. without loads and self-weight to support applied suitably braced rafters shall be Trussed „ „ „ „ „ „ „ „ „ „ 7

7 7. 2 „ „ „ Applicable wherethetrussis not restrainedby: Diagonal bracingtoendverticalofmono-pitchtrusses spacing betweenbracednodesislessthan3.7m. Applicable toallceilingnodepoints.Notnecessarywherethe Longitudinal bindersatceilingnodepoints is used. sarking, suchasOSB,timberboardingorplywoodsheeting, Applicable toalltrussedrafterroofs.Notnecessarywhererigid Longitudinal bracingmemberatridgenodepoint Intersection detailsshouldbeformedby: or staggered/steppedbuildings Bracing forroofslessthan6.6mwideondetached Bracing forroofsthatareapproximatelysquare „ „ „ cladding, i.e.plywood. a masonrywall,or 22mm x97mm600mmtimberspliceplate truss span less than3.7m truss span detail intersection truss span truss span

truss span „ „ Bracing formono-pitchtrusses Bracing forlargerroofs It shouldbeapproximately45°tothewebmembers. Requirement R5. be designedbyanengineerinaccordancewith Technical span andduo-pitchroofsover11m span,bracingshould Where thespanexceeds8m.Formono-pitchroofsofany Chevron bracingbetweenwebs Applicable toallrafternodepoints.Notnecessarywhere: Longitudinal bracingmemberatrafternodepoint „ „ „ „ sheeting, isused. rigid sarking,suchasOSB,timberboardingorplywood spacing betweenbracednodesislessthan4.2m,or driven throughbracingandclenchedover. round wirenailstoeachsideoftheintersection,with nailing, usingaminimumoffour35mmx65mmgalvanised less than4.2m truss span truss span

truss span detail intersection Pitched roofs more than8m truss span CHAPTER 7.2 truss span truss span detail intersection truss span

2020 truss span 8 8 7. 2

Also see: Clause 7.2.15 dormer rafter where carrying dormer cheek studs dormer cheek studs double joist carrying dormer cheek studs platform should be provided to 2 plate include securely fixed boarded walkways between the include securely fixed boarded walkways equipment; opening and the cistern or other permanent compressing the boarding should be securely fixed without or cistern, insulation; at each piece of permanent equipment a minimum 1m using herringbone (38mm x 38mm timber) or solid strutting x 38mm timber) or solid strutting using herringbone (38mm the depth of the floor and a minimum (a minimum of 0.75x of 38mm thick). facilitate maintenance. „ „ „ „ Rows of strutting None required One (at centre of span) (at equal spacing) Two d layboar

double rafter supports dormer cheek studs and load from the trimmer 2020

Provision of strutting lintel supports dormer roof trimmer takes load from cut rafters 7.2 CHAPTER Pitched roofs Pitched

hazardous locations not be located directly over stairs or in other permit the removal of permanent equipment (e.g. heating permit the removal of permanent equipment space and ventilation plant) located in the roof in each direction have a minimum opening width of 520mm be provided to the main roof space and voids which contain be provided to the main roof space and to roof cisterns and tanks etc. though it is not required spaces which contain only water pipes where the span between the node points which form the where the span between the attic truss exceeds 2.5m width of the floor of the supports to a floor within a cut where the span between roof exceeds 2.5m in accordance with the design in accordance with the „ „ „ „ „ „ „ Under 2.5m 2.5m-4.5m Over 4.5m Span of floor the fire-resistance period should be supported by test evidence. Dormer constructions shall be of adequate structural stability. Dormer constructions shall be of adequate structural stability. Dormer construction 7.2.13 Roof voids shall be provided with suitable access. Roof voids shall be provided with Access should: Access 7.2.12 Support for equipment for Support 7.2.11 shall be adequately supported. Permanent equipment in roof voids in MVHR fan units) is located in the roof void, the structure should be designed Where equipment (e.g. water tanks and manufacturer’saccordance with PD 6693-1 and the truss support the additional load. recommendations, to Table 5: Table Strutting should be provided: Strutting should be Strutting for attic trusses and cut roofs that form a floor that form roofs cut and trusses attic for Strutting 7.2.10 undue self-weight without applied loads and to support the shall be provided to attic trusses Strutting movement or distortion. „ „ „ „ „ „ „ Access hatches should be in accordance with Clause 7.2.15. Where an access hatch is required to provide fire resistance, Access hatches should be in accordance with Clause 7.2.15. Where an access 9

9 7. 2 „ „ „ „ „ „ „ „ „ „ „ „ Underlay should: Table 6: Underlay andsarkingshould: Underlay andsarkingshallbeprovidedtoresistthepassageofmoisture. 7.2.14 Underlay andsarking For dormerroofs: Table 7: In areasofsevereexposure,arigidsarkingwithunderlayisrecommended. At valleys: Less than15 Pitch Proprietary products Felt OSB (typeOSB3) Chipboard (typeP5) Exterior gradeplywood Tongued andgroovedorsquare-edgedboarding Material 35 15-34 „ „ „ „ „ „ „ „ „ „ „ „ laps, beheldinplacebybattens at verticallaps,befixedonlyoverrafters,andhorizontal be securelyfixed support traytopreventsagging(whichcanformawatertrap) be supportedbyacontinuousfilletorproprietaryeaves for theremainderofroof) felt oraproprietaryeavesguardused(type1Fmaybe where exposedateaveslevel,beUVresistantoroftype5U be providedasnecessary) the roofspaceorbetweenunderlayandsarkingshould underlay ishighlyvapour-resistant,increasedventilationto vapour resistance,i.e.lessthan0.25MNs/g(wherethe where itisaboverigidsarking(fullysupported),beoflow be providedtoalltiledroofs recommendations be inaccordancewiththemanufacturer’s rafters shouldbeusedtoprovidethenecessarysupport where cheekframesdonotextendtofloorlevel,twofixed or adoublefloorjoist cheek studsshouldbesupportedbyeitheradoublerafter construction shouldbeinaccordancewiththedesign used). underlay andhelddownbythe valleybattens(where a stripofunderlayshouldbelaid underthemainroof batten line the mainroofunderlayshouldbecuttovalley o andabove o Horizontal lapsforunsupportedunderlay Acceptable materialsforuseasunderlayandsarking o Minimum horizontallaps 150mm 225mm 100mm

Technical RequirementR3 BS EN13707 BS EN300 BS EN312 BS EN636serviceclass3 BS 1297 Standard „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ window frame. lintels shouldbestructurallyindependentfromthe a suitablelintelshouldbeprovidedovertheopening dormer framingandcladding support additionalloadsfromthemainroofmembers, trimming membersshouldbelargeenoughto be drapedtoallowwaterdrainbehindthetilingbattens. of 100mm at abutments,besupportedandturnedupbyaminimum with thehiprafter continue overhipstoforma150mmminimumlapparallel extend overtheridge where traditionalmortarpointingisusedtobedridgetiles, service penetrations be dressedintothegutterandcutneatlytofittightlyaround project throughtheunderlay be cutneatly, fittightlyandnotbetorn,i.e.wherepipes be usedinaccordancewithrelevantassessments. take accountofthetypeandfixingroofcovering Pitched roofs CHAPTER 7.2 dressed intogutter by tiltingfilletand underlay supported pitch ofroof lapped tosuit

2020

10 10 7. 2

y

5mm continuous high level ventilation with LR underla pipework. eaves ventilation. for mono-pitched roofs, cross ventilation should be in accordance with BS 5250 and have ventilation equivalent of a continuous high-level 5mm slot, in addition to A spacer in the eaves should be used to allow insulation to spacer in the eaves should A beyond the wall plate to minimise the be installed over and blocking the ventilation path (the spacer cold bridge without ventilation above should be of sufficient length to maintain the insulation). used, they should Where proprietary eaves ventilators are be fixed in accordance with the manufacturer’s instructions. resistant (type The roof is covered with high water vapour or the span HR) underlay and the pitch exceeds 35° ventilation). exceeds 10m (this is in addition to eaves „ „ „ „ c) „ „ „ „

10mm opening 5mm opening where pitch exceeds 35° or span exceeds 10m ° 2020

roof pitch over 15 10mm opening 7.2 CHAPTER Pitched roofs Pitched

ventilation, vapour control and insulation ventilation, vapour dormer construction be provided where the ceiling follows the slope of a roof, regardless of pitch, or where a cold roof has a pitch less than 15°, ventilation equivalent to a 25mm slot running the full length of the eaves should be provided (a nominal clearance of 50mm should be maintained between the insulation and the roof underlay) where the roof pitch is 15°or more, ventilation equivalent to a 10mm slot running the full length of the eaves should Vapour permeable underlays are used on sloping roofs with permeable underlays are used Vapour (e.g. flat roofed areas covered by non-permeable materials areas of mansard roofs). Unventilated cold roofs have insulation placed over a Unventilated cold roofs have insulation underlay horizontal ceiling and a vapour-permeable (type LR) is used. Ventilation paths should remain clear, i.e. not blocked by clear, paths should remain Ventilation insulation or the structure. Ventilation openings should prevent the entry of birds, etc. openings should prevent Ventilation openings are acceptable). (fabrications with 3mm-10mm „ „ „ „ „ „ Where high water vapour-resistant (type HR) underlay (e.g. types 1F/5U felts) is used, eaves ventilation should be provided on Where high water vapour-resistant (type HR) underlay (e.g. types 1F/5U felts) opposite sides of the roof to permit cross ventilation, and: account include: Ventilation, vapour control and insulation vapour control Ventilation, have insulation at ceiling level should in roof voids, pitched roofs that ventilation and to avoid condensation provide adequate To outside air: be ventilated to the a) b) Ventilation, vapour control and insulation and control vapour Ventilation, 7.2.15 into to be taken and cold. Issues condensation precautions against have adequate Roofs shall Ridge or high-level ventilation equivalent to a continuous opening of 5mm should be provided at the highest point of each roof to a continuous opening of 5mm should be provided at the highest point of each Ridge or high-level ventilation equivalent following situations: slope in accordance with BS 5250 in the „ „ „ „ „ „ 11

11 7. 2 „ „ „ Access hatchestocoldroofvoids shouldhave: provided tothehabitableareaspreventcondensationproblems inthehome. Where theceilingbelowacoldpitchedroofincludesvapour controllayer Vapour controllayersshouldbeprovidedinaccordancewith thedesign,andwhererequiredshouldbe: To reducemoistairenteringtheroofspace: opening tosuitpitch 10mm or25mm „ „ „ an airleakageratenotmorethan 1M placed onthewarmsideofinsulation the ceiling gaps shouldbesealedwhereservicespassthrough 2 PawhentestedtoBSEN13141-1, or opening 25mm opening 25mm opening 25mm mono-pitched roof

opening 5mm

room inroof(flatdormer)

cl

min. e

roof pitchbelow15°

ar ar

5

a

0mm 0mm

irwa y opening 5mm 3 opening 5mm /h atapressureof

opening 25mm clear airwa min. 50mm opening 25mm opening 25mm room-in-roof (partiallyslopingceiling) y

(

clear

min. 50mm) min.

ay airw „ „ „ „ „ „ cover compresses theseal). and frame(clampsmayalsobe requiredtoensurethatthe compress aclosedcellsealor ‘o-ring’ betweenthecover a push-upcoverwithminimum weightof5.5kgand the rafters. used inroofconstructionswheretheceilingboardisfixed to limit airleakage. where used,downlightersshouldbespecifiedandsealed to , thedesignshouldensureadequateventilationis opening 5mm opening ventilation pitched roofdormer opening 25mm Pitched roofs CHAPTER 7.2

room-in-roof (completelyslopingceiling)

(

clea

min. 50mm) min.

r

a airw

a coldbridg wall plateavoids cavity closeran insulation abov above insulation 25mm clearairwa spacer maintains cold roof y to suitpitch 25mm opening 10mm or e

2020 e d y opening 5mm 12 12 7. 2 y e y pipes insulated when abov loft insulation firestop below underla cavity closed at eaves firestop between batten and above underla Also see: Chapter 6.8 gaps sealed at services s rising main insulated above ceiling level loft hatch draught stripped cavity barrier of mineral wool or fire-resisting board in boxed eave ventilation opening lap the tank insulation and the loft insulation 3D above separating walls within the boxed eaves at separating walls. „ „ „ „ Standard BS EN 13162 BS 5803-2 BS 5803-3 Requirement R3 Technical

2020

Suitable materials for roof insulation Suitable materials for 7.2 CHAPTER Pitched roofs Pitched

a minimum 30min fire separation should be provided between the home and an integral garage. a cavity barrier of fire-resisting board or a wire reinforced mineral wool blanket (50mm minimum) nailed to the rafter and carefully cut to fully seal the boxed eaves should be installed (ordinary mineral wool quilt is acceptable as gaps between compartments should be sealed separating walls should stop approximately 25mm below the top of adjacent roof trusses, and a soft fire-resistant packing, such as mineral wool, should be used to allow for of the tiles movement in roof timbers and prevent ‘hogging’ at the junctions between a separating or compartment wall and a roof at the junctions between cavities firestopping above separating walls) ‘Cold rising’ pipework above ceiling level should be pipework above ceiling level should ‘Cold rising’ roof insulation. insulated, even where it is below the main Chapter 8.1 ‘Internal services’. Roof insulation should be placed above and around water tanks, but not below them. Where possible, water pipes should be below the main Where possible, water pipes should be pipes should be insulated in accordance with Water roof insulation. „ „ „ „ „ „ „ „ „ „ Mineral fibre mats Blown mineral fibre Blown cellulose fibre Proprietary products Material Combustible material, such as roof timbers and sarking felt, should be kept away from heat sources. Combustible material, such as roof timbers and sarking felt, should be kept away Pitched roofs shall be constructed to provide adequate fire resistance and separation. Pitched roofs shall be constructed to provide adequate fire resistance Firestopping should be provided in accordance with building regulations, including: on pipework, the following precautions should be taken: on pipework, the following precautions barriers and cavity Firestopping 7.2.16 In England and Wales, account should be taken of Accredited Construction Details. Accredited account should be taken of In England and Wales, Pipework reduce the risk of freezing or condensation forming To Dormer construction to eaves or from eaves to ridge. to dormers should be provided from eaves Ventilation Table 8: Table The thermal performance of the access hatch should access hatch should performance of the The thermal ceiling or performance of the to the overall thermal contribute bridging. and avoid cold the hatch is located, wall in which should be fitted and sealed to the Proprietary hatches in accordance with the surrounding construction manufacturer’s instructions. of sufficient thickness to meet the Insulation should be Regulations, and laid over the whole requirements of Building loft and wall plate. When providing firestopping: „ „ „ „ „ „ „ „ „ „ 13

13 7. 2 „ „ „ „ „ „ „ „ „ „ „ „ Battens shouldbe: Counter battensshouldbefixedtotheraftersandnotonlysarkingboards.

When coveringapitchedroof: Roof coveringsshallbeof asuitablequalityanddurabilitytoprotectthebuilding fromweather 7.2.18 Roof coverings Batten fixingsshouldbe: same rafter. Wherebattenspacingis: Battens shouldbesetouttoavoidjointsoccurringoverthe 1 Notes Table 9: Battens andcounterbattensshouldbe: Battens andcounterbattensshallbeadequatelysizedspacedtosupporttheroofcovering. 7.2.17 Battens Double lapslates Clay/concrete tiles „ „ „ „ „ „ „ „ „ „ „ „ established building practices coverings shouldbeinaccordance withthedesignand acceptable andringshanknailsshouldbeused) BS EN1991-1-4),galvanizedsmoothroundnailsarenot wind speedisover26m/s(National Annex FigureNA.1of ring shanknailswherespecified(wherethemaximumbasic a minimumof30mmlongerthanthebattenthickness a minimumof3.35mmx65mmlong(10gauge)and cut orwirenailsinaccordancewithBS5534 over any12consecutivebattens. 200mm orless,nomorethanthreejointsshouldbemade of fourshouldbejoinedoveranyonetrussorrafter more than200mm,noonebatteninanygroup the gutter set outsothatthetilesprojectaminimumof50mmover decreased asthiswouldreduceweathertightness) gauge requiredforthetileorslate(thelapshouldnotbe set outinstraightlinesparalleltotheridgeand three rafters a minimumof1.2mlongandspan treated withpreservative where cutendsareincontactwithmortar, preservative treated note andmarkedwiththesupplier, origin,gradeandsize in accordancewithBS5534,accompaniedbyadelivery Actual sizeshouldbewithin+/3mmofthenominalsize). Suitable battensizes Natural: sizedorrandom Fibre cementorconcrete Double lap Single lap

450mm span 25mm x50mm 25mm x38mm 25mm x38mm 25mm x38mm „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ recommendations, butnotlessthanshownin Table 9. sized inaccordancewiththeroofcoveringmanufacturer’s face oftheprotectingundercloak at verges,tilebattensshouldfinish25mm-50mmfromthe battens where onrigidsarkingboards,supportedcounter fixed throughcounterbattenstorafters fixed byskewdrivennailsoneachsideofthejoint. they span cut square,buttjointedoverraftersandnailedtoeachrafter suitability may be required). by NHBChasbeen granted(independentcertification of recovered materialsmaybeused wherepriorapproval mechanical nailgunsareused. guidancewhere in accordancewithmanufacturer’s coastal areas hot dipgalvanisedsteeloraluminium,whenusedin Pitched roofs CHAPTER 7.2 600mm span 25mm x50mm 25mm x50mm 25mm x38mm 25mm x50mm of four)joinedoverthesamerafte too manybattens(inagroup . spacing 200mm

2020

r 14 14 7. 2

Also see: BS 5534 (2) Minimum permissible pitch (°) 35 (clay) 35 (plain concrete) 30 20 subject to headlap . Issues to be taken into account vertical tiling and slating. double tiles, tile-and-a-half or half tiles can be used when available from the manufacturer (to avoid the use of where the tile Alternatively, small sections of cut tiles). manufacturer provides guidance, small sections of single lap tile can be bonded to full tiles the bottom edges of double-lapped slate and plain tile roofs should be finished with an under-eaves course. „ „ c) mortar d) „ „ Grade (to BS EN 12326) A1 T1 S1 Standard BS EN 1304 EN 491 BS EN 490 and BS BS 8612 BS EN 12326 BS EN 492 Established practices BS 6915 BS EN 12588 Advisory Services or other Thatching Standards set by the Requirement Technical with in accordance appropriate authority, R3 Association Grade 1 to the Canadian Standards Requirement R3 Technical Requirement R3 Technical 143 CP minimum, increased with lower . (1) 54mm Minimum headlap 65mm generally for clay tiles 75mm in severe exposure conditions 75mm or to the manufacturer’s recommendations pitch and severe exposure conditions 2020

Maximum 1/3 length lap Gauge Maximum 1/3 length lap Comply with the manufacturer’s recommendations Pitch, gauge and lap Standards relevant to roof coverings relevant to roof coverings Standards Acceptable characteristics for natural slates Acceptable characteristics for natural slates 7.2 CHAPTER Pitched roofs Pitched

For pitches below 30°, evidence shall be provided as to suitable performance. For pitches greater than 45° in sheltered and moderate exposure zones only eaves, ridge and hip tiles verges joints between tiles and slates should be slightly open, which provides some flexibility in setting out and should help to avoid tile cutting (single lap interlocking tiles have a tolerance of approximately 3mm at the joint) clay tiles that do not meet the dimensional and geometric requirements given in BS EN 1304 should not be laid at pitches less than 40° „ „ Slates (double lap) Type or tile Type Characteristics Water absorption less than 0.6% Water Thermal cycle Carbonate content less than 20% Plain (double lap) Concrete (single lap interlocking) Material Clay tiles and fittings Clay tiles Concrete tiles and fittings Dry fixed systems Natural slates and fittings Fibre cement slates Natural stone Lead sheet roofing Rolled lead sheet Thatch Shingles should be of western red cedar and zinc Sheet metal roofing, including lead, copper Proprietary roofs, roof lights and coverings Other roof coverings 2 Notes 1 Table 12: Table include: a) b) Coverings shall be suitably fixed to protect the building from weather Coverings shall be suitably fixed Fixing tiles and slates Fixing tiles 7.2.19 Table 11: 11: Table Careful setting out will improve the finished appearance of the roof, help avoid problems such as unequal overhangs, and reduce Careful setting out will improve the finished appearance of the roof, help avoid excessive tile cutting at abutments, chimneys and similar obstructions. When installing coverings: Table 10: Table Where slates and concrete or clay tiles are designated AA to BS 476-3, they can be used without limitation on pitched roofs. to BS 476-3, they can be used without AA are designated Where slates and concrete or clay tiles „ „ 15

15 7. 2 „ „ „ „ „ „ „ „ Proprietary dryfixedsystemsshouldbeinaccordancewithBS8612. ground floorbaywindows,donotrequiremechanicalfixing,unlessrecommendedbythemanufacturer joint thicknessof10mmwherewetbedded.Wet bedded‘baby’ hip/ridgetilestolowlevelroofs,suchasthoseoverporchesand Ridge andhiptilesshouldbemechanicallyfixedwithself-sealingnon-ferrousfixingsintotimberbattens,havea nominal Where ridgetilesaremortarbedded: on abargeboard. an undercloakofcement-based board,plaintileorslate.Plaintilesshouldnotbeusedas anundercloakbelow30°pitchor Unless aproprietarydryverge systemorcloakedvergeisused,tilesshouldbebedded into a100mmwidebedofmortaron Verges At hips: At eaves: Eaves, ridgeandhiptiles When fixingcoveringstoapitchedroof: „ „ „ „ „ „ „ „ parallel withthehiprafter underlay shouldcontinuetoforma150mmminimumlap the underlayshouldextendoverridge. recommendations. accordance withthetilemanufacturer’s the heightoffaciashouldmaintaintilepitch,in should beused when usingslatesorplaintiles,anunder-eavescourse tiles shouldprojectaminimumof50mmacrossthegutter to BS1202-3orcopper1202-2). (these shouldbeeithersiliconbronze,aluminium slates andtilesshouldbefixedusingcloutorslatenails recommendations and themanufacturer’s coverings shouldbefixedinaccordancewiththedesign Requirements R3andR5mayberequired) (evidence ofcalculationsincompliancewith Technical be inaccordancewithBS5534andEN1994-1-4 manufacturer; fixingsforsingleanddoublelaptilesshould the fixingscheduleshouldbeproducedbytile

„ „ „ „ „ „ „ „ „ „ twice wherecentrenailed. slates shouldbefullynailedoverthewholeroof,and tile clipsshouldbeofplastic,aluminiumorstainlesssteel minimum of15mmintobattens fixings shouldbeaminimumof38mmlong,andpenetrate (but areacceptableforfixingbattensorunderlay) galvanized steelnailsshouldnotbeusedforslatesandtiles centre lineofthegutter. at thebasebyagalvanizedhipironandprojectto where wetbeddedtilesareused,theyshouldbesupported over ridge carried underla y Pitched roofs CHAPTER 7.2 . across thegutter a min.of50mm coverings toproject under-eaves tiles into gutterbelow underlay dresse mechanically fixed in mortarand ridge tilesbedded d

2020

16 16 7. 2 n underlay take over wall cavity m 100m m m verge tiles bedded in mortar on undercloak 38-50m or 30-60m at dormer cheeks, the tiles or slates should be specified to be cut close to the slope of the roof and over a flashing fixed to the side of the dormer. natural slate verges should be formed with full slates and natural slate verges should be formed with are a minimum of either slate-and-a-half or half slates that 150mm wide. of cut interlocking small sections (less than a half tile width) tiles should not be used. pointing should be completed as soon as possible using the same mix. tiles should be wetted on their contact surface, and surface water allowed to drain away before fixing concealed or decorative dentil tiles should be fully bedded into joints in excess of 25mm thick. at internal or external angles, purpose-made corner tiles or soakers should be used to form a weathertight joint where pitched roofs abut tiled walls, a stepped flashing should be specified and turned in behind the tiles ush with the flush with the struck off roofing mortar and bedded on exterior a suitable of the wall (alternatively, external surface should be used in accordance with grade bedding sealant the manufacturer’s recommendations) true line where a bargeboard is used. securely nailed to a „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „

2020

cut tiles avoided at verges 7.2 CHAPTER Pitched roofs Pitched

tile-and-a-half tiles used for correct coursing

the moisture barrier should be underfelt or equivalent batten sizes should be in accordance with this chapter every tile or slate should be nailed twice and the bottom edges should be finished with an under-course tile where the supporting structure is of timber construction, the moisture barrier should be used with a breather membrane a suitable moisture barrier should be used where the wall structure is solid brickwork or blockwork, where they are shown to have similar strength, durability and workability) the mortar should be 1:3 cement:sand with plasticiser the mortar should be a mix based on sharp sand with soft sand added to achieve workability; the proportion of sharp sand should not be less than one third of the total sand content (proprietary mixes may be accepted by NHBC or bargeboard gable wall they should project 30-60mm beyond the or bargeboard cut plain tiles are not acceptable, and purpose-made plain cut plain tiles are not acceptable, and purpose-made tile-and-a-half tiles should be used they should project 38-50mm beyond the gable wall they should project 38-50mm beyond the installed at the correct level to ensure that the line of the installed at the correct it passes over the wall, and not tiling is maintained where fixed in accordance with manufacturer’sfixed in accordance recommendations a true line installed to tilt inwards „ „ „ „ „ „ „ „ „ „ „ „ „ When fixing vertical tiling and slating: Vertical tiling and slating Vertical Mortar When bedding tiles or slates in mortar: Where verge tiles and slates are wet bedded, pointing should be completed as soon as possible using the same mix. pointing should be completed as soon as possible using the same mix. Where verge tiles and slates are wet bedded, resist uplift, nailed twice to battens and sized to ensure that they are in direct clips should be in full contact with the tile to Verge tile. contact with the top surface of the verge the verge: Where plain tiles and slates are used at Undercloak should be: Undercloak Where interlocking tiles are used at the verge: Where interlocking tiles are used at the „ „ „ „ „ „ „ „ „ „ „ „ „ 17

17 7. 2 „ „ „ „ „ Where apitchedroofabutsthewallatanangle: 75mm abovetheintersectionwithroof. flashing topreventwaterpenetratingintoanenclosedarea.Horizontalflashingsshouldprovideweatheringaminimum of Where aflatorpitchedroofoveranenclosedareaabutswall,balconycavitytraysshouldbelinked tothe Table 13: flashings comeintocontactwithmetal,theyshouldbeformedusingnon-ferrousmaterial. Flashing detailsshouldbeappropriatefortheroofandtypeofcoveringused,inaccordancewithBS5534.Where b) a) to resistthepassageofmoistureinsidebuilding.Issuesbetakenintoaccountinclude: Weatherproofing shallbeprovidedatabutments,flatroofintersections,changesinslopesandprojections 7.2.20 Weathering details At abutments: Abutments Copper alloys Aluminium and Material products Proprietary Zinc alloy Rolled leadsheet „ „ „ „ „ 3D 150mm wide stepped flashingsshouldbecutfromastripminimumof should beused a steppedcavitytraylinkedtoflashing minimum ofoneperstepforsteppedflashings wedged inplaceatnotmorethan450mmcentres,ora flashings shouldbetucked25mmintoabrickjointand lead flashingsshouldhaveaminimumlapof100mm provided asnecessary flashings, soakersandguttersshouldbe flat roofintersectionorchangesinslope abutments Suitable materialsforflashings 75mm min. BS EN1172 BS EN515 Standard Technical R3 Requirement BS EN988 BS EN12588 up behindflashin underlay turned min. 150mm g

exposur depends on flashing; method clip freeedgeof below wallDPC wedged intojoin lead flashing e „ „ „ „ Flashings, soakersandsaddlesshouldbe: bituminous paint 0.6-0.9mm thick,andprotectedfromcontactwithmortarbyacoatingof Additional information manufacturer’s recommendations manufacturer’s Should besecurelyfixedinaccordancewiththe Should beaminimumof0.6mmthick Flashings, gutterliningsetc.should: „ „ „ „

sections shouldnotexceed1.5minlength be aminimumofcode4,andsoakers3 0.55mm thick(0.7mmissuitableforgutters) fully annealed t

„ „ „ d) c) „ „ „ soakers (orasecretgutter)shouldbeinstalled. where slates,flatinterlockingtilesorplainareused, stepped flashingsshouldbeaminimumof65mmwide recommendations. accordance withthemanufacturer’s with cementmortarorsuitableexteriorgradesealantin joints betweenthemasonryandflashingshouldbepointed copings. projections throughtheroof 3D by theflashin tile andoverlapped soakers beneatheach Pitched roofs CHAPTER 7.2 g

with leadwedges held inmortarjoint stepped leadflashing Also see:Chapter6.8 up atabutment underlay turned

2020 s

18 18 7. 2

min. 150mm front apron flashing cover flashing back gutter flashing upper DPC tray stepped side flashing lower DPC tray underlay overlaps weatherproofing approx. 150mm fall 3D where pipes penetrate tiling, a weathertight joint should where pipes penetrate tiling, a weathertight upstand or a be formed using a lead slate flashing and by the roof purpose-made one-piece accessory (supplied are used they covering manufacturer); where lead slates should be supported (e.g. using exterior grade plywood) to prevent sagging. ashing should saddle flashing should the main roof, a a ridge meets meets the main roof. be used where a ridge the flat roof should where the flat roof is over a dormer, or sides. have a fall to the front „ „ „ „ „ „

d

back gutter flashing supporte by gutter boards r 2020

lead saddle flashing dressed lead saddle flashing dressed over GRP valley gutter GRP valley gutte m g back gutter min. 150m cover flashin 7.2 CHAPTER Pitched roofs Pitched

flashings should be provided (e.g. at chimneys) components should be installed according to the components should be installed according manufacturer’s recommendations the lowest course of tiles or slates should not touch the the lowest course of the waterproof membrane should be carried up under the the waterproof membrane above the flat roof, and lapped tiling to a height of 150mm by the roofing underlay the change is 5° or more (e.g. at mansards and sprockets), at mansards and sprockets), is 5° or more (e.g. the change should be used flashings or soakers roof membrane 3D „ „ „ „ „ Where there is a projection through the roof: Where there is a projection through the Projections through the roof Flat roof intersection or changes in slope intersection or Flat roof and: with a flat roof slope, or an intersection is a change in the Where there at roof adjoins a pitched roof: Where a flat roof adjoins a pitched „ „ „ „ „ 19

19 7. 2 „ „ „ „ „ „ „ „ „ „ „ „ „ „ lower DPCunderthebracket,andinstallingnextsectionofoverittocreatealapthatcoversfixingpoint. Fixing methodsthatpenetratetheDPCshouldbedesignedtoensureweathertightness. DPCs shouldbeinstalledunderthecopingtoensurethatwallisweathertight. Where theroofcoveringisslateorplaintiles,following maybeused: Further guidancecanbefoundinChapter6.2‘Externaltimberframedwalls’. Where valleysareformedusing valleytiles: Valleys usingvalleytiles Valleys, andthecomponentsused,should: inside ofthebuilding. Valleys shallhavesuitableweatheringdetails,includingflashings,toresistthepassageofmoisture 7.2.21 Valleys andhiddengutters Where GRP copings areused,theyshould: The bracketsshould: To resistwindupliftandgravitationalforces,L-shapedbracketsshouldbeusedtosecurestonecopingsmasonrywalls. using suitablydurablefixings,andbeweathertight. Copings, includingthosemanufacturedfromnaturalstonereconstitutedstone,andGRP Copings „ „ „ „ „ „ „ „ „ „ „ „ „ „ tiles gutter boardswhere theroofusessinglelap interlocking purpose-made valleytroughtiles shouldbesupportedby the roofusesplaintiles purpose-made valleycoursing tilesshouldbeusedwhere A sweptvalley. A lacedvalley. small cuttilesshouldbeavoided recommendations manufacturer’s be fixedinaccordancewiththe recommended fortheroof have afinishedpitchwhichcomplieswiththeminimum be inaccordancewiththedesign include aDPC instructions be fixedinaccordancewiththemanufacturer’s extend thefullwidthofwall assessed inaccordancewith Technical RequirementR3 be bitumen-basedmaterialtoBS6398,orother (such astype304toBSEN10088-2) be manufacturedfromstainlesssteel have dowelbarsthatfitintorestraintholesinthecopings DPC support brackets stainless steel DPC suppor t

lead soaker lead flashing s „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ be supportedoverthecavity. be fullybeddedinmortar suitable length,gaugeanddurability. be fixedtoasolidpieceofmasonry, withfixingsofa wide channel(minimum 125mmforpitchesbelow 30°). they shouldbe beddedinmortarwithaminimum 100mm junction, andpreferablybecut fromtile-and-a-halftiles adjacent coveringsshouldbe neatlycuttoformasmooth they shouldbemechanicallycut tothecorrectrake A mitredvalleywithsoakers. Requirement R3. non-ferrous metaloraproprietarysystemto Technical tiles (plaintiles),valleytrough(interlocking be formedusingeitherpreformedGRP, valleycoursing saddle flashing,attheheadofeachvalley have aleadflashing(minimumcode4)orothersuitable allow fornormaldownwardmovementinthetimberframe. DPC The DPCshould: clip , shouldbesecurelyfixedtogablewalls This canbeachievedbyextendingthe Pitched roofs fixing strip continuous CHAPTER 7.2

flashing omittedforclarit adjoining roofcoveringand cavity closer seal compression plywood plat GRP coping

2020 y e

20 20

7. 2

Also see: Chapter 3.3 . ’s recommendations, and securely fixed to recommendations, and ’s , the downpipe should be fitted with shoes. and are laid with a sufficient fall towards the outlet, and are laid with a sufficient fall towards unless designed to be flat. with splayed butt joints. above 30°. with stop ends, installed ensuring gutters are provided where timber is to be painted, it should be knotted and primed on all surfaces before fixing where timber requires a stained finish, one coat of stain should be applied before fixing each joint should be cut and fixed neatly. laid in strips no longer than 1.5m laid in strips no longer of 150mm, where pitches are lapped by a minimum the correct type fixed in accordance with the design, using outlets etc. to of fittings for internal and external angles, ensure efficient drainage of the roof the supported and jointed in accordance with manufacturer’s recommendations in accordance with insulated when passing through a home, Chapter 8.1 ‘Internal services’ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ BS EN 636 Class 3 BS EN 12467 BS EN 12467 Requirement R3 Technical

; however, ; however, 2 2020

Materials acceptable for facia boards 7.2 CHAPTER Pitched roofs Pitched

consideration should be given to providing drainage to consideration should be given to providing porch roofs and balconies smaller roofs such as dormer, (see Clause 7.1.12) pretreated with preservative twice to each rafter where preservative treated timber is cut or planed, preservative should be applied to the cut edge timber for fascias, bargeboards and soffits should be timber for external feature work should be free from waney edges, large knots, resinous pockets, splits and other unsightly defects designed and fitted to prevent erosion of the lower surface, designed and fitted to prevent erosion onto where water from a large roof surface discharges another surface of a sufficient size to accommodate normal rainfall, of a sufficient size to accommodate normal provided where roofs are greater than 6m and sized to cope with concentrated flows, i.e. where supported on gutter boards of 19mm exterior grade ply, or boards of 19mm exterior grade ply, supported on gutter design as specified in the either code 4 (colour-coded blue) or code 5 either code 4 (colour-coded (colour-coded red) there are dormer roofs „ „ „ „ „ „ „ „ „ High density fibre reinforced calcium silicate board Glass fibre reinforced cement (GRC) board Proprietary products Exterior grade plywood Table 14: Table Fascias and trim Fascias 7.2.23 shall be appropriately fixed and treated against decay Fascias, bargeboards and soffits Drainage should be: Drainage 7.2.22 rainwater to a suitable outlet. Roof drainage shall adequately carry Proprietary gutter or valley systems Proprietary gutter with the manufacturer valley systems should be in accordance Proprietary gutter or grade materials should be used). suitable supports (exterior Lead-lined valleys Lead-lined bedded on an mortar should be tiles, except that the bedded as for valley should be cut and valleys, the tiles For lead-lined bridge the welt detail. Mortar should not lead and the mortar). contact between the (to prevent direct undercloak Lead should be: When installing fascia boards and soffits: Where gutters are behind parapet walls, a suitably sized overflow should be provided. Where gutters are behind parapet walls, level, or above a drainage gully Where a downpipe discharges above ground Fascia boards should be fixed: „ „ „ „ „ „ „ „ „ 21

21 7. 2 „ „ generally beacceptabletoNHBC. Spandrel panelsthatcomplywithguidancefromtheStructural Timber Association orthe Trussed Rafter Association will designed, manufacturedandinstalledtoprovidesatisfactoryperformance.Itemsbetakenintoaccountinclude: Spandrel panelsusedincoldroofvoidstocreateseparationbetweendwellingsorformtheinnerleafofgablewallsshouldbe Spandrel panelsshallprovidesatisfactoryperformance. 7.2.24 Spandrel panels „ „ acoustic transfer fire resistance „ „ structural stability. Pitched roofs CHAPTER 7.2

2020 22 22

7. 2 Internal services CHAPTER 8.1 This chapter gives guidance on meeting the Technical Requirements forinternal services, including: „„the supply of hot and cold water „„plumbing „„gas „„electrical installations.

8.1.1 Compliance 01 8.1.2 Provision of information 01 8.1.3 Water services and supply 01 8.1.4 Cold water storage 03 8.1.5 Hot water service 04 8.1.6 Soil and waste systems 05 8.1.7 Electrical services and installations 06 8.1.8 Gas service installations 07 8.1.9 Meters 07 8.1.10 Space heating systems 08 8.1.11 Installation 08 8.1.12 Extract ducts 10 8.1.13 Testing and commissioning 11

Also see: Chapter 2.1 Also see: Also see: water regulations and guides, BS EN 806 Also see: water regulations and guides, durability protection from the cold. Central heating pipe runs. Underfloor heating pipe runs. Gas supply pipe runs. units. Electrical outlets, switches and consumer „ „ „ „ c) d) „ „ „ „ 2020

‘Specifications for installations inside buildings conveying water for human consumption’. ‘Specifications for installations inside buildings storage water heaters’. Specification for indirectly heated unvented (closed) supply. ‘Water ‘Copper and copper alloys. Seamless, round tubes for water and gas in sanitary and heating copper applications’. ‘Copper indirect cylinders for domestic purposes’. ‘Specification for copper hot water storage combination units for domestic purpose’. and heating installations in ‘Thermoplastics pipe and fitting systems for hot and cold water for domestic purposes buildings’. water for domestic use within ‘Guide to the design, installation, testing and maintenance of services supplying buildings and their curtilages. Complementary guidance to BS EN 806’. 8.1 CHAPTER Internal services Internal

Compliance

suitability of materials and components suitability of materials and components adequate supply Location and size of water storage cisterns and cylinders. Location and size of water storage cisterns Hot and cold water pipe runs. Location of sanitary fittings. Drainage runs. „ „ „ „ BS EN 806 BS EN 12897 BS EN 1057 BS 1566 BS 3198 BS 7291 BS 8558 Designs should be issued to site supervisors, relevant specialist subcontractors and suppliers, and include the following relevant specialist subcontractors and suppliers, and include the following Designs should be issued to site supervisors, information: installed to ensure satisfactory service for the life of the system, Components shall be selected and Relevant standards for materials and components used in domestic water systems include: Relevant standards for materials and components Suitability of materials and components a) b) Water services and supply services Water 8.1.3 main. based on the pressures and flow rates supplied from the incoming services shall be Water Clear and fully detailed drawings should be available on site to enable work to be carried out in accordance with the design. be available on site to enable work to be carried out in accordance with the design. Clear and fully detailed drawings should Provision of information of Provision 8.1.2 include all relevant a clearly understandable format, shall be produced in Designs and specifications personnel. be distributed to the appropriate information and corrosion and damage. Issues to be taken into account include: with suitable precautions taken against Internal services which comply with the guidance in this chapter will generally be acceptable. comply with the guidance in this chapter Internal services which sites, should be provided of gas i.e. radon or gas, from landfill against ground hazards and the entry Adequate precautions 8.1.1 ground of service entries, and take account Requirements with the Technical services shall comply Internal attack. hazards and chemical as necessary. Further guidance can be found in BRE Report 211 ‘Radon: guidance on protective measures for new dwellings’, measures for new dwellings’, ‘Radon: guidance on protective BRE Report 211 Further guidance can be found in as necessary. and BRE Report 212 ‘ Construction of new buildings on gas-contaminated land’. ‘ Construction of new buildings on gas-contaminated and BRE Report 212 „ „ „ „ 1

1 8.1 The watersystemshouldbecapableofbeingdrained(hotandcoldservicesseparately). „ „ „ „ „ „ „ „ „ Table 1: unheated spaces,theyshouldbeinsulatedandnotaffected bycold.Insulationshouldbeprovided: To reducetheriskoffreezing,waterservicesshouldbelocatedinwarmenvelopehome.Wheretheyare Protection fromthecold by thewatersupplier. fitted duringmanufactureinaccordancewiththerelevantBritishStandard.Sacrificialanodesshouldbeinstalledwhere required In areaswherepittingcorrosionofcoppercylindersoccurs,itmaybenecessarytofitaluminiumprotectorrods. The hotandcoldwaterserviceshouldbeinstalledusingcorrosionresistantpipesfittings. Durability The designandinstallationofthewaterservicessupplyshould: Adequate supply The conditionsassumedforthe tableare: diameter (mm) Outside pipe 15 22-28 „ „ „ „ „ „ „ „ „ water temperature+7°C air temperature-6°C especially nearopeningstotheoutsideair, suchaseaves) (particular careisneededaroundbendsandjunctions, with Tables 1and2),cisternsventpipes around waterservices,includingpipework(inaccordance (surge arrestersmayberequired) occur withinthesystemandpotentiallydamagefittings account forpressurefluctuationsandsurges,whichmay supply pipemayberequiredinsidethehome) account forpressureandflowratereductions(awider valve insidethehome ensure aminimum20L/minflowrateisavailableatthestop stop valveinsidethehome be basedonaminimum1.5bardynamicpressureatthe drinking water storage cisterncontaininganadequatesupplyof from thesupplypipeor, wherethisisimpracticable,froma ensure drinkingwaterisprovidedatthekitchensinkdirect requirements andtherecommendationsofwatersupplier be inaccordancewithbuildingregulations,statutory Minimum insulationthicknesstodelayfreezinginsidedomestic premisesforcoldwatersystems cold air

0.025 Thermal conductivityofmaterialat0°CW/(mK) Minimum insulationthickness(mm) 30 12 water pipes insulated

0.030 45 15

„ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ materials andfittings. supplier, includingcompatibilityofthesupplywith be inaccordancewiththerecommendationsofwater of corrosion be ofmaterialswhicharesafeandminimisetherisk prevent theentryoffluids,verminandinsects ensure thatundergroundductsaresealedatbothendsto mechanical damage precautions shouldbetakenagainstfrostand ground surface–wherethisisnotpossible,adequate ensure servicepipesareaminimumof750mmbelowthe home areprotectedbyashaftorbox ensure thatstopvalveswithinthecurtilageandoutside ice formation50%. in accordancewithBS6700orEN806and8558. on eachsideofraisedtanksinunheatedroofspaces as specifiedinthedesign(butnotbeneathacoldwatertank) 0.035 70 19 Internal services CHAPTER 8.1 0.040 91 24 thickness insulation These shouldbe

2020

2 2 8.1

ventilated void to suspended floor any distance min. 750mm the stronger axis (as marked on board) at right angles to the bearers. to supply cold water outlets (where not connected to the to supply cold water outlets (where not mains supply). the positions have holes neatly formed with a cutter in shown in the design be suitably supported. Storage capacity for small homes – supplying hot and cold outlets – 200-300L. per bedroom. Storage capacity for larger homes – 100L water level in the should be situated 25mm from the shut-off cistern may dip below the water level in accordance with water regulations, terminate vertically downwards or be fitted with a horizontal tee where it discharges. oriented strand board type OSB3 to BS EN 300, laid with „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „

2020

Material foam. Rigid phenolic and rigid polyurethane foam. Polyisocyanurate foam PVC foam. polyethlene foam, expanded nitrile extruded polystyrene, cross-linked Expanded polystyrene, polyethylene foam. rubber and improved cellular glass. foam, expanded synthetic rubber and Standard polyethylene

Examples of insulating materials: Examples 8.1 CHAPTER Internal services Internal

chipboard type P5 to BS EN 312 softwood boarding marine plywood should be adequately sized (19mm minimum) should be provided at each cold water cistern, to a suitable external discharge, unless permitted by water regulations where it may be internal if it is conspicuous Storage capacity for small homes – only cold water be accessible for inspection and maintenance (non-airtight) that be protected by a rigid close-fitting cover also excludes light and insects to supply an open vented hot water storage system to supply an open vented hot water storage (where required by the water supplier) fittings – 100-150L. „ „ „ „ „ „ „ „ „ Thermal conductivity W/(mK) Thermal conductivity Less than 0.020 Less than 0.020-0.025 0.025-0.030 0.030-0.035 0.035-0.040 Cold water service shall be provided in accordance with statutory requirements and be adequate. Cold water service shall be provided with suitable capacity and include primary feed cisterns where indirect water heating Cold water storage should be provided should be provided: systems are installed. Cold water storage Cold water storage water Cold 8.1.4 Table 2: Table Where the floor is of suspended construction, the underfloor of suspended construction, the underfloor Where the floor is be insulated as it passes through the water service should space. ground and the ventilated Cisterns should: BS 6700 provides the following recommendations: and overflow pipes: Warning „ „ „ „ „ „ „ „ „ The cistern bottom should be continuously supported by materials such as: 3

3 8.1 „ „ „ „ appliances require greatervolumes,thecapacity shouldbeincreasedaccordingly. Hot waterstorageshouldcomply withtheminimumcapacityin Table 5(based onadraw-off temperatureof60°C),andwhere 5 4 3 2 1 Notes Table 4: 3 2 1 Notes Table 3: Hot waterservicesshouldbedesignedinaccordancewith Tables 3,4and5,and: demand andconsumption. Hot waterserviceshallbeprovidedinaccordancewithstatutoryrequirementsandadequateforthe 8.1.5 Hot water service Access should: Bath only Bathroom Outlet Sink Wash basin Shower (non-electric) Bath (fromcombi) Bath (fromstorage) „ „ „ „ supply fallsbelow1.5bar be lesswherethepressureandflowrateofincoming statutory requirementsandgenerallybeavailable;itmay the minimumflowrateshouldbeinaccordancewith hazardous locations not belocateddirectlyoverstairsorinother 520mm ineachdirection be viaanopening(accesshatch)withaminimumwidthof containing onlywaterpipes) cisterns andtanks,etc.(notrequiredtoroofspaces be providedtothemainroofspaceandvoidsthatcontain instantaneous systems(combinationboilers) willbelimitedbytheirperformanceasquotedtheboilermanufacturer The hotwatersystemshouldsupplyat leastthehotwaterdemandstatedandtakeaccountofdistributionheatlosses throughthepipework. Demand basedonuseoftheshower in preferencetothebath. Demand basedonminimumacceptable boileroutput. Demand basedon‘Design’ flowrateofbath. Shower maybeoverthebathorinaseparateenclosurewithinbathroom. least 50°Cwithin1minuteofrunningthewater. The supplytemperatureistheatoutlet.InaccordancewithBS8558wateranoutletorthermostaticmixingvalveshould beat The minimumflowrateshouldbeavailableateachfittingwhenthatisusedsimultaneouslywithoneormoreotherfitting(s)asshownin The designflowrateshouldbeusedtoestablishthehotandcoldpipesizesprovidequotedateachoutletwhenthatison its own.    Hot waterdemandandsimultaneoususe Flow rateandtemperaturerequirements (2) Bath +Shower    Design flowrate L/sec 0.20 0.15 0.20 0.20 0.30 (4) (4) (2) (1) 1st Showerroom Shower room

(L/min) (12) (9) (12) (12) (18) (1)       (3) 2nd Showerroom „ „ „ L/sec 0.10 0.10 0.10 0.15 0.15 Minimum flowrate „ „ „ maintenance purposes not belessthantheminimumrate). discharge occurs,theflowrateatindividualoutletsshould total demanddoesnotexceed0.3L/s(wheresimultaneous have thedesignflowrateavailableateachoutletwhen the insulation). (boarding shouldbesecurelyfixedwithoutcompressing opening andthecisternorotherpermanentequipment include securelyfixedboardedwalkwaysbetweenthe include aminimum1m    (L/min) (6) (6) (6) (9) (9) Internal services 0.25 0.35 0.20 0.20 0.15 0.20 L/sec 0.20 0.30 Hot waterdemand (2) 2 platformlocatedfor . CHAPTER 8.1 55 40 40 40 48 Supply temperature°C (5) (15) (21) (12) (12) (9) (12) (L/min) (12) (18) Also see:BS8558 The suitabilityof Table 4.

2020

(3) 4 4 8.1

soil pipe or ventilation pipe m 180L Two baths Two 900m min. less than 3m Also see: BS EN 752 and BS EN 12056 (1) openings where vented, should be provided with an expansion pipe. where vented, should be provided with installed by competent installers. accessible for maintenance insulated as specified in the design. located to facilitate replacement switch. fitted with an on/off for a second bath after 20 minutes. for a second bath after as required storage combination boilers have the capacity prioritise hot water 5. Where boilers can control and Table in than the figures outputs the storage capacities can be less 4 subject to manufacturer’s recommendations on Table in meeting the demand. „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ 145L Bath and shower(s) Bath and

2020

120L Bath only

Minimum storage requirements Minimum 8.1 CHAPTER Internal services Internal

Maximum of two showers (excludes instantaneous electric showers). Maximum of two showers fitted to prevent the entry of vermin. fixed neatly and securely to provide the correct falls adequately ventilated at each branch arranged to ensure foul air from the drainage system cannot enter homes (e.g. ventilated to 900mm above openings when within 3m) in accordance with the requirements of the water supplier adequately ventilated at the head of underground drains controlled by a thermostat (this may be by a soil pipe or separate ventilation pipe) appropriate for the type of water supplied to the home supported in accordance with manufacturer’s recommendations unless designed otherwise installed vertically, assessed in accordance with Technical Requirement R3, or Technical assessed in accordance with and be the subject meet the requirements of BS EN 12897 (applies to both of third-party certification, e.g. Kitemarking the assembled system and components) require a suitable space for the siting of the storage vessel require a suitable space for the siting of simultaneous demand for hot water is limited. Where there simultaneous demand for hot water is limited. simultaneous are three or more outlets, the design for sink discharge can omit the outlet at the kitchen

immediately after the bath has been filled, for tasks such immediately after the as washing „ „ „ „ „ „ „ „ „ „ „ „ „ „ 60L Shower only Soil and waste systems should be: Soil and waste systems shall be in accordance with relevant building regulations and installed to ensure Soil and waste systems shall be in accordance with relevant building noise and smell. that effluent is removed without affecting health or creating unnecessary Soil and waste systems and waste Soil 8.1.6 Where systems are heated by off-peak electricity, the storage capacity should be in accordance with the recommendations of the with the recommendations of the storage capacity should be in accordance electricity, heated by off-peak Where systems are electricity supplier. hot water: should be able to provide adequate one bathroom or shower room, the system Where homes have Note 1 Table 5: Table Unvented hot water storage systems should be: Unvented hot water storage systems should Hot water cylinders should be: Where an immersion heater is fitted, it should be: Where homes have two or more bathrooms, the system should be able to provide adequate hot water immediately after each of be able to provide adequate hot water two or more bathrooms, the system should Where homes have filled, for tasks such as washing. the baths have been not provision should be made to ensure that the outlet temperature of the water is Where a shower is installed, adequate of a thermostatic This may be achieved by the provision by the use of other hot or cold outlets in the home. significantly affected of pipe sizes or dedicated supplies. shower mixing valve, the appropriate design boilers) produce hot water on demand (generally at lower flow rates than Instantaneous systems (using combination where: storage systems), and should only be used than instantaneous systems, and: Storage systems provide higher flow rates „ „ „ „ „ „ „ „ „ „ „ „ „ „ 5

5 8.1 The junctionsofwalltilingwithbathsandshowersshouldbemadewatertightusingaflexiblesealanttoaccommodate „ „ „ „ „ „ „ „ „ „ „ Rooms shouldbeprovidedwiththeminimumnumberof13A outletslistedin Table 6(dualoutletscountastwo). Waste disposalunits shouldbe: through homesby: Sound insulationshouldbeprovidedtosoilpipespassing movement. The manufacturer’s instructionsshouldbefollowed. movement. The manufacturer’s Table 6: Electrical servicesandinstallationsshould: The installationshallensuresafeandsatisfactoryoperationbeprotectedfromchemicalattack. Electrical installationsshallbeprovidedinaccordancewithrelevantregulations,codesandstandards. 8.1.7 Electrical services andinstallations Sanitary fittingsshouldbe: Air admittancevalvesshould: Hall Landing Dining room Bedrooms Living orfamilyroom Kitchen/utility Room „ „ „ „ „ „ „ „ „ „ „ through thethicknessofeachsound-insulatingfloor). unfaced mineralfibre(theinsulationshouldbecontinued material andwrappingthepipewithaminimum25mmof relevant buildingregulations have fittingsandcomponentslocatedinaccordancewith 300/500 V, forelectricpowerandlighting’. PVC sheathedcablesforvoltagesuptoandincluding comply withBS6004‘Electriccables.PVCinsulatedand electrical installations’ comply withBS7671‘Requirementsfor fitted withatubulartrap(notbottleorresealing) provided withadequatesupport fixings appropriatetotheweightofitembeingsecured secured usingnon-ferrousorstainlesssteelscrews installed withaccessories,suchaschainsandplugs an encasedboxing,usingaminimum15kg/m not bepositionedinareaswhichareliabletofreezing Technical RequirementR3 BS EN12380orbeassessedinaccordancewith where usedtoterminateasoilpipe,complywith avoid theneedtoventilateitadequately) be used to allow air to enter the drainage system (but do not Minimum numberofoutlets 2 2 4 6 (4) 8 8 Outlets rooms. A minimumofsixoutletsforthemainbedroomandafourotherbed A minimumoftwooutletsnearthe TV aerialoutlet. general use. utility roomfour. Whereappliancesareprovided,aminimum ofthreeoutletsshouldbefreefor Where homeshaveseparateareas,thekitchenshould aminimumoffouroutletsandthe Notes

2 board

„ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ otherwise specifiedbythemanufacturer) polystyrene insulation. ensure PVCcoveredcablesarenotincontactwith sized andderated thermal insulation,unlesstheyhavebeenappropriately ensure cablesarenotplacedunder, againstorwithin recommendations manufacturer’s be installedinaccordancewiththe manufacturer’s instructions. manufacturer’s connected tothedrainagesysteminaccordancewith fitted toensureWClidsandseatsarestablewhenopen. fitted withoutusingexcessivepacking for maintenance. where positionedwithinthehome,beaccessible (the ventilationareashouldbe2500mm boxing orventilationoftheintoaventilatedroofvoid achieved byventilationgrilles,discreetgapsaroundthe have freemovementofairaroundthemwhichcanbe Also see:BREreport‘Thermalinsulation:avoidingrisks’ Internal services CHAPTER 8.1 15 kg/m should haveamassof the materialofenclosur unfaced mineralfibr wrapthe pipewith25mm line theenclosureor timber framing

2 2 minimumunless e

2020

e

- 6 6 8.1 in shaded zone 150mm wide Also see: Chapter 6.1 cavity tray y meter box Also see: Chapters 6.2, 6.8, BS 6400 and BS 6891 Also see: Chapters 6.2, 6.8, BS 6400 and vertically or horizontall to switch or outlet a conduit and draw wire or suitable alternative. where there is a gas supply to the home, a gas point at This is not required the cooker space should be provided. where an electric hob is provided where gas pipework is to be installed in timber frame, movement. allowance is made for differential in the common areas of homes and controlled by either in the common areas of homes and controlled controls. manual switching or automatic light-sensitive to the side of where provided, have cooker panels located the cooker space. „ „ „ „ „ „ „ „ „ „

2020

Meters 8.1 CHAPTER Internal services Internal

Individually purpose-made compartments in accordance with the recommendations of BS 6400. Surface-mounted (on an external wall). Semi-concealed (sunk into the ground adjacent to the Built-in (to the outer leaf of the wall). DPCs and cavity trays lintels (except for purpose-designed built-in meter boxes). outer wall). installation of pipework and appliances complies with relevant standards and codes including those published by the Institution of Gas Engineers and Managers (IGEM) or Gas Safe Register (GSR) service pipework up to and including the emergency control valve and meter is in accordance with the requirements of gas supplier and primary meter owner the gas transporter, and terminated a concealed, coaxial cable from the roof void to a terminal a concealed, coaxial cable from the roof outlet in the main living room have a 13A socket outlet where there is a gas supply socket outlet where there have a 13A have a minimum 30A supply which is suitably switched supply have a minimum 30A in each room, hall, landing and staircases in a staircase with two-way switching at each floor level within the shaded zone in the diagram, or within the shaded zone from the surface of a wall, or a minimum a minimum of 50mm in or bottom of a timber joist, or batten of 50mm from the top a floor or ceiling. vertically or horizontally from the outlet or switch being served the outlet or switch horizontally from vertically or „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ Openings in walls for meter cabinets shall be structurally adequate and prevent dampness entering the home. Openings set into external walls should be provided with: 8.1.9 Gas service installations shall be adequate and comply with the gas safety regulations, and be in Gas service installations shall be and codes to ensure safe and satisfactory operation. accordance with relevant standards Gas service installations should ensure: Gas service installations Gas service 8.1.8 Aerials are not required; however, one of the following should be provided: Aerials are not required; however, Electrical supply to gas appliances a suitable fixed spur or socket outlet should be provided. supply, Where a gas appliance requires an electrical TV Cooking spaces Cooking spaces should: Lighting outlets should be provided: Lighting outlets should Lighting outlets Cables without special protection, such as an earthed such as an earthed special protection, Cables without metal conduit, should be positioned: should be positioned: metal conduit, Domestic meters may be of the following type: Meters and associated equipment should be located to be reasonably accessible and not subject to damage. Where the position of switches or sockets can be determined of switches or sockets can be determined Where the position of the wall or partition, the zone on one from the reverse side applies to the reverse side. side of the wall or partition „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ 7

7 8.1 The provisionofwholehomeorcentralheatingisdiscretionary. Whereprovided,itshouldbedesignedinaccordancewith „ „ „ „ „ „ „ „ Pipes should: Where copperpipesarepermitted infloorscreeds,theyshouldbe: Table 7,recognisedstandards,and: including: Space heatingappliances,includingallcomponentsandcontrols,shouldbeofatypeapprovedbytherelevantauthority, Where appropriate,spaceheatingsystemsshouldcomplywiththefollowing: ensure safeoperation. Where spaceheatingisprovided,itshallbeinaccordancewiththerelevantcodesandstandards, 8.1.10 Space heating systems Table 7: Services should: Fitting ofpipesandcables b) a) satisfactory operation.Issuestobetakenintoaccount include: Internal servicesshallnotadverselyaffectthestabilityofhomeandbeinstalledtoensure 8.1.11 Installation Room BSRIA guideBG4/2011 BS EN12828 BS 8303 BS EN14336 BS 5410 Living room Dining room Bedroom Hall andlanding Kitchen Bathroom Toilet „ „ „ „ „ „ „ „ but notrestrict thermal movement be installedneatly withclipsspacedtoprevent sagging, be adequately secured withsuitableclipsor brackets length andatjointsbends sleeved orwrappedsothatthey canmovefreelyalongthe structural elementsandnotsolidlyembedded be protectedbyasleeve,orducted,whenpassingthrough floors’ wheretheypassthrough thesubstructure comply withChapter5.1‘Substructureandground-bearing accordance withBSEN12828 air changeusedforthedesignshouldbeincreasedin where roomscontainopenfluedappliances,therateof bathrooms shouldaccountforanymechanicalventilation the numberofairchangesperhourfromkitchensand Testing & Approval Scheme Solid fuel–Fuel Association, HeatingEquipment notching anddrillingofjoists fitting ofpipesandcables Room temperaturesandventilationrates

Room temperature°C 21 21 18 18 18 22 18 ‘Underfloor heatingandcooling’. ‘Heating systemsinbuildings.Designforwater-basedheatingsystems’. ‘Installation ofdomesticheatingandcookingappliancesburningsolidmineralfuels’. systems. Heating systemsinbuildings.Installationandcommissioningofwaterbasedheating ‘Code ofpracticeforoilfiring’.

„ „ „ „ „ „ „ „ „ „ c) „ „ „ „ „ „ „ „ „ „ heat outputaspartofawholehomeheatingsystem the mainlivingroomshouldhaveaheatingapplianceor not byperformancetests design temperaturesshouldbeverifiedbycalculationsand Oil –OFTEC. Electricity –BritishElectrotechnical Approvals Board contraction toavoid damageandnoise. be installedwith adequateroomforthermal expansion and have adequate falls(whereappropriate) jointed withcapillaryjoints. of practice. not beburiedinscreedsunlesspermittedbyrelevantcodes electricity metertails not belocatedinthecavityofanexternalwall,exceptfor a -3°Cexternaltemperature. temperature calculationsshouldbebasedon concealed services. Internal services Ventilation rate(airchangesperhour) 1.5 1.5 1 1.5 2 2 2 CHAPTER 8.1 Also see:Chapter6.8

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8 8 8.1 h . Where chases h

holes located on the centre line in a zone (0.25-0.4 x span) from the end and max. diameter = 0.25 x joist dept Maximum size 0.15 x depth of joist 0.25 x depth of joist 0.25 x depth of stud holes separated by a min. 3 x hole diameter . notches located in a zone (0.1-0.2 x span) from the end and max. notch depth = 0.15 x joist dept 1/3 thickness for vertical chases. it is close to heavy loads, such as those from partitions, cisterns, cylinders and stair trimming. using lead-free flux recommended by the pipe manufacturer, manufacturer, pipe the by recommended flux lead-free using immediately after jointing. with traces removed be designed by an engineer. „ „ „ „ „ „ „ „

Top edge 0.1-0.2 x span Top Centre line 0.25-0.4 x span Centre line 0.25-0.4 x height Location 2020

100mm min. between notches and holes Limits for notching and drilling solid timber members Limits for notching and drilling solid timber 8.1 CHAPTER Internal services Internal

1/6 thickness of the single leaf for horizontal chases the dimensions are not in accordance with Table 8, or Table the dimensions are not in accordance with the joist is deeper than 250mm, or comply with the clauses below, or below, comply with the clauses strictly in accordance with the manufacturer’sstrictly in accordance instructions „ „ „ „ „ Notching joists up to 250mm in depth Drilling joists up to 250mm in depth Drilling studs Concealed services of the surface does not occur Services concealed in walls or floors should be located so that significant cracking Lightweight steel framed walls and floors’. Light weight steel should be used in accordance with Chapter 6.10 ‘Light steel Preformed holes are provided, and additional holes and notches should not be cut without the approval of the manufacturer. Preformed holes are provided, and additional holes and notches should not be Metal web joists position. in fixed are joists the before inserted be to need may Conduits webs. metal the between gaps the in run should Services I-joists in walls are necessary, their depth should not exceed: in walls are necessary, Where the structural strength is impaired by notching or drilling, the element should be replaced or correctly repaired. by notching or drilling, the element should be replaced or correctly repaired. Where the structural strength is impaired of three times the hole diameter. Holes should be spaced at a minimum distance of 100mm. Notches and holes in the same joist should be separated by a minimum horizontal Instructions should be obtained from the designer when notching and drilling, where: Solid timber and studs 8: Table Notching and drilling of joists Notching and drilling and cables should either: chasing to accommodate service pipes Notching, drilling and trate fire-resisting floors, walls or partitions. Where a proprietary penetrate fire-resisting floors, be provided around any services which Fire stopping should in accordance with the manufacturer’sintumescent seal is used, it should be installed system, such as an instructions. Metallic tape should be placed behind plastic pipework, where it is concealed behind wall surfaces, and would otherwise not be otherwise not be surfaces, and would behind wall where it is concealed behind plastic pipework, should be placed Metallic tape similar equipment. a metal detector or located by should be made: Joints in pipes Hollow blocks should not be chased unless specifically permitted by the manufacturer „ „ „ „ „ 9

9 8.1 Alternatively, theductworkcanbefittedwithacondensatetrapthatdischargestooutsideorinstallingductslope „ „ „ „ „ „ „ „ the outside. intermittent extractsystem,theyshouldberestrictedtoamaximumof: Bends shouldgenerallybeformedwithproprietaryrigidcomponents.Whereflexibleductisusedtoformbendsonan insulating material,and: Screed covershouldbeaminimumof25mmoverpipesand using: equivalent toaminimumof25mminsulatingmaterialwith athermalconductivityof0.04W/(mK). Where extractductworkpassesthroughunheatedspaces, itshouldbecontinuouslyinsulatedtoachieveathermalresistance Control ofcondensation resistance doesnotpreventthedesignedventilationratefrombeingachieved.Flexibleductshouldbeinstalled: Rigid ductispreferabletoflexible,butwhereflexibleused,itshouldberestrictedinlengthensurethatthe airflow Ductwork systemsshouldbedesignedtominimisetheresistanceairflow Resistance toairflow should betakenintoaccountinclude: The firerequirementsofthebuildingshouldbeinaccordancewithrelevantregulationsandstandards.Issues that engineer inaccordancewith Technical RequirementR5. recommendations,orbedesignedbyan are required,thisshouldonlybecarriedoutinaccordancewiththemanufacturer’s adversely affect thestructuralorfireperformanceofbuilding.Wherealterationstoelements,suchasI-joists, The routeofductworkshouldtakeaccountotherbuildingelements.Ductworkpassingthroughstructuralelements should not Building integration c) b) a) satisfactory performanceanddurability. Issuestobetakenintoaccountinclude: Ductwork tointermittentandcontinuouslyrunningmechanicalextractventilationsystemsshallensure 8.1.12 Extract ducts Pipes underfloorscreedsshould: „ „ „ „ „ „ „ „ suitable pre-insulatedductwork,or two forsystemsupto30L/s straight the locationandtypeofdampersfirestopstobeused elements ofthebuilding suitable detailingofcomponentspassingthroughother achieve adequatecover where pipescross,itmaybenecessarytoformaduct particularly atchangesofdirection. have adequateallowanceforthermalexpansion, be protectedbywrappingorducting control ofcondensation resistance toairflow building integration condensate trap space unheated condensate toeave pipe todrain

s „ „ „ „ „ „ e) terminals. d) „ „ „ „ „ „ of pipesshouldbeapprovedbythedesigner. for in-sitususpendedconcretefloors,thelocationanddepth a proprietaryinsulationsystem. one forextractrateshigherthan30L/s. recommendations. in accordancewiththemanufacturer’s the integrityofwallsandfloors. the integrityofprotectedstairsandhalls installation , andbeformedfromcompatiblecomponents. Internal services space unheated CHAPTER 8.1 min. 25mmcover within screed insulated pipe This canbeachievedby the outside duct slopingto Also see:Chapter8.3

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10 10 8.1

to ensure leaks or other defects are made good prior to the to ensure leaks or other defects are made application of finish and handover of the home. sealed mechanically fixed joints and connections. sealed mechanically „ „ „ „

r 2020

terminal extracting to open ai insulation removed for clarity 8.1 CHAPTER Internal services Internal

of practice where pipes are located under screeds (including air or water testing before and after the screed is laid) in accordance with all relevant regulations and codes in accordance with all relevant regulations adequate support throughout its length adequate support throughout „ „ „ Services should be tested: Testing and commissioning Testing 8.1.13 to ensure satisfactory operation. Services shall be tested and commissioned Terminals freely to open air. systems should terminate Ventilation Airflow resistance of performance of the ventilation system. the of terminals should not adversely affect The air flow resistance in accordance with BS EN 13141-2. terminals can be obtained through testing Installation fixed, and have: be securely manner, in a neat and workmanlike should be installed Ductwork Before completion and handover of the building services should be commissioned in accordance with relevant regulations and Before completion and handover of the building services should be commissioned codes of practice. Where ductwork passes through an external wall, it should be positioned to slope slightly outwards to prevent water entering be positioned to slope slightly outwards through an external wall, it should Where ductwork passes manufacturer’s 750mm apart. they should not generally be more than recommendations. For rigid ductwork, transfer noise to the home. such as plasterboard ceilings, that may be in direct contact with other surfaces, Ductwork should not the building. Clips and supports for ductwork should be spaced at equal distances and in accordance with the ductwork at equal distances and in accordance supports for ductwork should be spaced the building. Clips and „ „ „ 11

11 8.1 Low or zero carbon technologies CHAPTER 8.2 This chapter gives guidance on meeting the Technical Requirements for low or zero carbon (LZC) technologies.

8.2.1 Compliance 02 8.2.2 Provision of information 03 8.2.3 Clean Air Act 03 8.2.4 System design 03 8.2.5 Access 04 8.2.6 Handling, storage and protection 04 8.2.7 Sequence of work 04 8.2.8 Location 04 8.2.9 Building integration 04 8.2.10 Fixing 05 8.2.11 Electrical installation requirements 06 8.2.12 Pipes, insulation and protection from cold 06 8.2.13 Ground collectors 06 8.2.14 Fuel storage 07 8.2.15 Safe discharge 07 8.2.16 Testing and commissioning 07 8.2.17 Handover requirements 07 8.2.18 Further information 07 discharge storage vessel feed pump hot water store expansion vessel + relief valve output condenser feed compressor expansion valve hot water store output evaporator ground collector solar thermal boiler 2020

Solar thermal water heating to space and/or Systems which convert solar radiation energy water heating. Heat pump The heat from low energy sources. Systems which transfer air. are ground, outdoor air and exhaust most common sources output (export) feed output (export) import meter export meter import meter export meter hot water store output AC mains supply AC mains supply output (demand) output (demand) generation meter pump generation meter unit inverter

unit inverter expansion vessel consumer consumer biomass boiler input PV array 8.2 CHAPTER Low or zero carbon technologies carbon zero or Low

The illustrations provided within the introduction are generic and do not indicate the only possible systems acceptable to NHBC. The illustrations provided within the introduction are generic and do not indicate

Systems which convert wind energy into electricity. turbine Wind Solar photovoltaics (PV) electricity. Systems which convert solar radiation into Systems which burn wood pellets or chips for space and/or wood pellets or chips for space and/or Systems which burn water heating. Biomass boiler Introduction systems that to NHBC. Other acceptable carbon (LZC) technologies on low or zero provides guidance This chapter with NHBC. acceptable, subject to specific agreement principles of this chapter may also be follow the general chimneys and flues’. are given in Chapter 6.8 ‘Fireplaces, for solid fuel and oil fired boilers Additional requirements 8.1 ‘Internal services’. internal services is given in Chapter Guidance on other guidance on the following technologies: This chapter provides 1

1 8.2 LZC shouldcomplywithrelevantstandardsincludingwhereapplicable: Relevant standards LZC technologiesthatcomplywiththeguidanceinthischapterwillgenerallybeacceptable. b) a) Definitions for thischapter LZC technologiesshallcomplywiththeTechnical Requirements.Issuestobetakenintoaccountinclude: 8.2.1 Compliance Switchgear Split system Renewable energy Refrigerant pipework Performance generation Parallel electrical system stem Open loop BS EN303-5 BS EN12809 BS EN14785 BS EN61400-2 BS EN61400-1 BS EN14511 BS EN61215 BS EN12976-1 BS EN12975-1 (LZC) technologies Low orzerocarbon mode operation) Islanding (island Inverter condensation Interstitial Ground collectors Exclusion zone Controls product certification relevant standards

Terminology, requirements,testingandmarking’. ‘Heating boilersforsolidfuels,handandautomaticallyfired, nominalheatoutputofupto300kW ‘Residential independentboilersfiredbysolidfuel’. ‘Residential spaceheatingappliancesfiredbywoodpellets’. ‘Wind turbines.Smallwindturbines’. ‘Wind turbines’. space heatingandcooling’. Parts 1-4‘Airconditioners,liquidchillingpackagesandheat pumpswithelectricallydrivencompressorsfor ‘Terrestrial photovoltaic(PV) modules-Designqualificationandtypeapproval’. ‘Thermal solarsystemsandcomponents.Factorymadesystems’. ‘Thermal solarsystemsandcomponents.Solarcollectors’. equipment. The combinationofelectricalswitches,fusesand/orcircuitbreakersusedtoisolate and thetwoarelinkedbyrefrigerantpipework. A typeofheatpumpinwhichthecondenserislocatedindoors,evaporatoroutdoors, the windandtides,fromreplaceablemattersuchaswoodorotherplantmaterial. Energy fromnaturallyavailablesourcesthatcanbereplenished,includingenergythesun, and mustbeinsulatedprotectedfromdamage. Carries refrigerantbetweentheindoorandoutdoorunitofasplitsystem.Normallymadecopper The mannerorqualityoffunctioningforamaterial,productsystem. grid andon-sitesourcessuchaswindturbinesphotovoltaicpanels. A systeminwhichbuildingloadscanbefedsimultaneouslyfromthenationalgridorelectricitysupply exchanger andreturnsitunderground. A heatpumpsystemthatextractswaterfromanundergroundsource,pumpsitthrougha efficient thantraditionalsolutions,orwhichemitlesscarboninprovidingheating,coolingpower A termappliedtorenewablesourcesofenergy, andalsototechnologieswhicharesignificantlymore unscheduled lossofmainssupply. Where anLZCtechnologyfeedsthenetworkorlocaldistributionsystemduringaplanned A devicethatconvertsdirectcurrentintoalternatingcurrent. wall construction,oftenoccurringduetocoldbridging. Condensation causedbyvapourfromwithinthebuildingcondensingoncoldersurfaces incorporated intoproprietaryfoundationsystems. Collectors canbeinstalledeitherhorizontallyorverticallyintheground. They mayalsobe The componentofagroundsourceheatpumpsystemwhichabsorbsfromtheground. injury orlossoflife. An areawhereentryisrestrictedduringperiodswhenmaintenanceinprogress,topreventriskof Controls areusedtooperateand/orregulatethesystemandmaybeelectricalormechanical. Low orzero carbon technologies Also see:Chapter2.1and c) operative competency. www.microgenerationcertification.org CHAPTER 8.2

2020 .

.

2 2 8.2

Air Act 1993 or Air ’s recommendations, certification scheme requirements ’s compatibility the effect on neighbouring properties, particularly the the effect positioning of the LZC technology in relation to openings. On-site testing requirements. Commissioning schedule. certified to a standard acceptable to NHBC. certified to a standard Interface details. Specification for controls. 2020 „ „ „ „ „ „

d) e) performance. „ „ „ „ „ „ 8.2 CHAPTER Low or zero carbon technologies carbon zero or Low

acoustics systems vibration internal and external noise Fixing schedule. A full set of current drawings. A specifications. Manufacturers’ Indication of which manufacturer and/or installer is Indication of which manufacturer and/or responsible for each system and interface. competent and familiar with the system being installed, and with the system being installed, and competent and familiar „ „ „ „ „ „ „ Design and location should take account of: Acoustics Location as orientation, roof pitch and shading. The design and location of LZC technologies should take account of factors such in accordance with the manufacturer’sFor stand-alone wind turbine systems, suitable exclusion zones should be provided recommendations and geographical location. LZC technologies should be designed in accordance with the manufacturer a) location b) c) Clean Air (Northern Ireland) Order 1981. Clean Issues to be taken into LZC technologies shall be designed to ensure satisfactory performance. account include: and appropriate standards. System design System 8.2.4 Biomass boilers installed in smoke controlled areas shall comply with relevant legislation. Biomass boilers installed in smoke smoke controlled area should comply with the Clean Biomass boilers to be installed within a 8.2.3 Air Act Clean Design and specification information should be issued to site supervisors, relevant specialist subcontractors and suppliers, be issued to site supervisors, relevant specialist subcontractors and suppliers, Design and specification information should Designs and specifications shall be produced in a clearly understandable format, include all relevant be produced in a clearly understandable format, include all relevant Designs and specifications shall all appropriate personnel. information and be distributed to Installers who have been trained in accordance with the MCS installer standards will generally be acceptable to NHBC. installer standards will generally be been trained in accordance with the MCS Installers who have information of 8.2.2 Provision LZC systems should be installed by operatives: LZC systems should and include the following information: Operative competency Product certification Product authority by an appropriate independent assessment confirming satisfactory current certification should have LZC technologies to NHBC. acceptable Scheme (MCS) will generally be the Microgeneration Certification installations that are assessed through Systems, products and request. should be made available to NHBC upon Certification and test documentation acceptable to NHBC. NHBC to be a suitable where they are considered by bodies or test documentation may be acceptable Other certification alternative. „ „ „ „ „ „ „ 3

3 8.2 „ „ „ „ prevent detrimentaleffects arisingfrom movementorvibration. The designofthestructureshouldtakeaccountof: The structuretowhichtheLZCtechnologyisattachedshould beassessedaccordingtoitsabilityaccepttheloadingsand Requirement R5towithstandthestructuralforcesactingupon them. Foundations andanchorpointsforstand-aloneLZCtechnologies shouldbedesignedbyanengineerinaccordancewith Technical LZC technologiesshallbesecurelyfixedandnot adverselyaffecttheweatherresistanceofbuilding. 8.2.9 Building integration recommendations. manufacturer’s LZC technologies,includingancillarycomponentsshouldbe locatedandidentifiedinaccordancewiththe LZC technologiesshallbecorrectlylocated. 8.2.8 Location recommendations. accordance withthemanufacturer’s To ensureperformance,certainLZCsystemsandancillarycomponentsshouldbeinstalledinalogicaltimelysequence LZC technologiesshallbeinstalledinaccordancewithasuitableschedule. 8.2.7 Sequence of work 8.2.6 Handling,storage andprotection recommendations. manufacturer’s enable thecleaning,inspection,maintenanceandrepairofsystems. Access shouldbeprovidedinaccordancewiththe Safe accessshouldbeprovidedtotheLZCtechnologies,includingswitchgear, inverters,metersandcontrols. This isto repair ofLZCtechnologies. Appropriate arrangementsshallbeprovidedforthepurposesofcleaning,inspection,maintenanceand 8.2.5 Access performance requirementsinChapter8.1‘Internalservices’. LZC technologiesdesignedtocontributetowardsspaceandwaterheatingshouldbeinaccordancewiththe Performance Multiple systemsshouldbecompatiblewitheachother. recommendations. accordance withthemanufacturer’s LZC technologiesshouldbeinstalledsoasnottoadverselyaffect theperformanceofbuildingtowhichtheyarefixed,andin Compatibility satisfactory performance. However, wherecomponentsfrommorethanonemanufacturerareused,theyshouldbecompatibletoensure Each systemshouldgenerallybesuppliedfromonemanufacturerasapackageandnotindividualcomponentsormaterials. Systems LZC technologiesshouldbe: prevent damage,distortion,weatheringanddegradation. Materials, productsandsystemsshallbehandled,storedprotectedinasatisfactorymannerto „ „ „ „ wind loads imposed loads the self-weightofLZCcomponents recommendations the manufacturer’s transported, lifted,handledandstoredinaccordancewith Low orzero carbon technologies „ „ „ „ „ „ „ „ dynamic loading(whererelevant). snow loads protected toavoidtheriskofdamage. delivered insequencetoavoidstorage CHAPTER 8.2

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4 4 8.2 mounted integrated flow – out flashing support and head flashing solar panel flow – in seal with membrane sill flashing Also see: Chapter 2.1 eatherproofing details that rely solely on sealant are eatherproofing details that rely solely on 3D 3D 2020

Guidance Minimum code 4. BS EN 12588. thick and protected from contact with mortar by BS EN 485 and BS EN 573, 0.6-0.9mm a coating of bituminous paint. BS EN 988 and 0.6mm thick. Where two metals are to be joined, 0.55mm thick and fully annealed. BS EN 1172 bimetallic corrosion in that environment they should be compatible and not cause they should be isolated from each other. Alternatively, Requirement R3. Technical Assessed in accordance with Guidance NA NA BS EN ISO 3506 treatment in Coatings to BS EN ISO 2081, BS EN ISO 2082, BS EN 1461, or other appropriate accordance with BS EN ISO 12944 or BS EN ISO 14713. BS EN 573 and BS EN 755 BS EN 10088 BS EN 10346 Requirement R3. Technical Assessed in accordance with

Materials suitable for fixings Materials for flashings 8.2 CHAPTER Low or zero carbon technologies carbon zero or Low

have adequate protection against corrosion. have adequate protection be designed to take account of ventilation and drainage be designed to take LZC technology requirements of the accommodate all static and dynamic loads in accordance accommodate all static with the manufacturer’s recommendations „ „ „ Phosphor bronze Silicon bronze Stainless steel Mild steel Aluminium alloy Stainless steel Mild steel Other materials Fixing material Flashing material Rolled lead sheet Aluminium and aluminium alloys Zinc alloys Copper Proprietary flashing, including plastic and composite. Fixings should comply with the types listed in Table 2. Table Fixings should comply with the types listed in 2: Table Fixing 8.2.10 LZC technologies shall be fixed using durable materials. not acceptable. Flashings should be formed from the materials listed in Table 1. Table from the materials listed in not acceptable. Flashings should be formed Table 1: Table All interfaces between the LZC technology and the building should ensure adequate weather resistance, sealed to limit air leakage and the building should ensure adequate weather resistance, sealed to limit All interfaces between the LZC technology The its presence. by interior or any part of the structure that could be adversely affected and prevent moisture from reaching the appropriate flashings and fixings. W envelope should be weatherproofed using Notching, drilling or chasing of structural components to structural components drilling or chasing of Notching, comply cables should either service pipes or accommodate by an or be designed 8.1 ‘Internal services’, with Chapter R5. Requirement Technical accordance with engineer in and mounting frames should: Fixings, supports, bracketry To avoid potential surface or interstitial condensation, the design should take account of thermal bridging, particularly where any avoid potential surface or interstitial condensation, the design should take account of thermal bridging, particularly To part of the system, including fixings, penetrates the thermal envelope. Where two metals are to be joined, they should either be Where two metals are to prevent bimetallic corrosion. compatible or isolated, Aluminium and aluminium alloys should not come into contact alloys should not come into contact Aluminium and aluminium with cementitious material. „ „ „ 5

5 8.2 „ „ „ „ Ground collectors shouldbeprotectedandtested priortobackfilling. and hedgerows. and otherservices.Designshould takeaccountoflocalplanningauthorityguidance,including excavationsthatareclosetotrees Excavations fortheinstallation ofgroundcollectorsshouldnotadverselyaffect aquifers,foundations, drainage,watersupplypipes proposed, consultationwiththeappropriateenvironmentagency shouldbemadeandmayrequireoneormoreofthefollowing: The depthandlayoutofgroundcollectorsshouldbespecified toavoidfreezingofadjacentground.Whereopenloopsystemsare The installationofgroundcollectorsshalltakestructural andenvironmentalfactorsintoaccount. 8.2.13 Ground collectors cycle andsuitablecondensatedrainage. Air sourcesystemsshouldincorporateanautomaticdefrost control layertopreventicebuild-up. insulated, andtheinsulationshouldincorporateavapour recommended bythemanufacturer. The pipeshouldbe be ofrefrigerantqualitycopperpipeorothermaterialas Refrigerant pipeworkconnectingsplitsystemsshould insulated, particularlywhenat,orcloseto,groundlevel. Where thereisariskofpipesfreezing,theyshouldbe their intendeduseinaccordancewith Technical RequirementR3. affected bymoistureorvapour. They shouldalsocomplywithrelevantcodesandstandardsorbeindependentlyassessedfor in accordancewith Technical RequirementR3.Insulationmaterials shouldbeinert,anddurable,notadversely life ofthesystem.Pipesshouldcomplywithrelevantcodesandstandardsorbeindependentlyassessedfortheirintended use Materials usedforpipesandinsulationshouldbesuitabletheintendedpurposeprovidesatisfactoryperformance forthe designed topreventfreezing. All pipeworkandinsulation,includingrefrigerantpipework,shallensureadequateperformance be 8.2.12 Pipes, insulationandprotection from cold loss ofmainssupply. This isknownas‘islanding’. mains powerfailure. This istopreventthemfromfeedingthenetworkorlocaldistributionsystemduringaplannedunscheduled LZC technologieswhichgenerateelectricityandareconnectedtothemainsshouldautomaticallydisconnectwhenthereisa or testing. The electricalinstallationshouldbecapableofbeingisolatedfromallothersourceswhenrequired,formaintenance ER G59/3-2. certificate andcomplywithallotherpartsofERG83/2forstandardinstallations.Largerinstallationsshould Where parallelelectricalgenerationoccurs,invertersshouldhaveacurrentEngineeringRecommendationG83/2typetest Electrical installationsshouldcomplywithBS7671‘RequirementsforInstallations’. The electricalinstallationshallbeinaccordancewithrelevantregulations. 8.2.11 Electrical installation requirements Issues thatshouldbetakenintoaccountinclude: The type,size,number, recommendations. positionandfittingtoleranceoffixingsshouldbeinaccordancewiththemanufacturer’s Materials thatcomplywithrecognisedstandards,whichprovideequalorbetterperformancetothoseabove,arealsoacceptable. „ „ „ „ An abstractionlicence. A licencetoinvestigategroundwater. the isolationofdissimilarmetals the provisionofsuitablelockingnutsandwashers Low orzero carbon technologies „ „ „ „ the isolationofaluminiumfromcementitiousmaterial. A dischargeconsent. outside air from the heat absorbed external unit CHAPTER 8.2 internal unit quality copperpipe insulated refrigerant

2020

to space provided heat

6 6 8.2

’s ’s BS EN ISO 14713-3:2017. Zinc coatings. Guidelines and recommendations for the protection against corrosion of iron and steel in structures. Sherardizing loads on roof-mounted BRE Digest DIG 489 Wind photovoltaic and solar thermal systems’. a completed installer’s certificate from an acceptable MCS or independent assessment organisation, suitable alternative details of the fuel type and source maintenance and servicing requirements warranties and/or guarantees for the LZC technology. BS EN ISO 14713-2:2009. Zinc coatings. Guidelines and recommendations for the protection against corrosion of iron and steel in structures. Hot dip galvanizing volume to take account of peak load and period of demand of peak load and period of demand volume to take account separation to prevent fire and gases fire resistance and of the building. entering other parts the correct operation of the system. 2020 „ „ „ „ „ „ „ „ „ „

„ „ „ „ „ „ „ „ „ „

Also see: The HVCA Guide to Good Practice Installation of Biofuel Heating (TR/38) Installation of Biofuel Guide to Good Practice The HVCA Also see: 8.2 CHAPTER Low or zero carbon technologies carbon zero or Low

BS EN ISO 14713-1:2017. Zinc coatings. Guidelines and recommendations for the protection against corrosion of iron and steel in structures. General principles of design and corrosion resistance ER G83/2-1 Recommendations for the Connection of Type ER G83/2-1 Recommendations for the Connection of Type per (Up to 16A Small-scale Embedded Generators Tested Distribution Systems Phase) in Parallel with Low-Voltage ER G59/3-4 Recommendations for the Connection of Generating Plant to the Distribution Systems of Licensed Distribution Network Operators’ CE72 Energy efficiency best practice in housing. Installing small wind-powered electricity generating systems: Guidance for installers and specifiers Renewable Energy Association (REA) Renewable Energy a completed manufacturer’s certificate from an acceptable independent assessment organisation, MCS or user instructions for the systems installed user instructions for the systems installed installer contact details for the manufacturer and key components installed suitable alternative the correct installation of the system the safety of the system fire detection and extinguishing equipment where elevated equipment where elevated fire detection and extinguishing dust levels are expected access for delivery „ „ „ „ „ „ „ „ „ „ „ „ „ Further information Further 8.2.18 Detailed information and instructions shall be provided to the homeowner. Detailed information and instructions homeowner should include: The pack of information provided to the Handover requirements Handover 8.2.17 Upon completion, the installer should provide a certificate to confirm that the LZC technology has been installed, tested and a certificate to confirm that the LZC technology has been installed, tested Upon completion, the installer should provide commissioned in accordance with the above. The installer should check that the system is in accordance with the certification requirements, the manufacturer The installer should check that the system Testing and commissioning Testing 8.2.16 and commissioned in accordance with the commissioning schedule. LZC technologies shall be tested Solar thermal water heating systems should discharge into a storage vessel. The discharge pipework and vessel should be The discharge a storage vessel. heating systems should discharge into Solar thermal water suitable to withstand high temperatures. Safe discharge Safe 8.2.15 safely. technologies shall terminate Discharge from LZC to be taken into account include: recommendations and the design. Issues Fuel stores should have appropriate: Fuel stores should have Fuel storage Fuel 8.2.14 installation. suitable for the boilers shall be for biomass Fuel storage „ „ „ „ „ „ „ „ „ „ „ „ „ 7

7 8.2 Mechanical ventilation with heat recovery CHAPTER 8.3 This chapter provides guidance on mechanical ventilation with heat recovery (MVHR) systems acceptable to NHBC.

8.3.1 Compliance 01 8.3.2 Provision of information 01 8.3.3 Building integration 01 8.3.4 Noise 02 8.3.5 Design considerations 02 8.3.6 Access and operation 04 8.3.7 Ductwork 04 8.3.8 Fixing and jointing of ductwork 04 8.3.9 Commissioning and balancing 05 8.3.10 Handover requirements 05

© Designed and produced by NHBC

Also see: Chapter 7.1 and 7.2 Technical Booklets in Northern Ireland Technical 2020

MVHR fan unit intake ductwork terminal (intake) air valve (supply) exhaust ductwork air valve (extract) terminal (exhaust) service ductwork (extract) service ductwork (supply) firestopping. trained in accordance with the BPEC installer scheme, trained in accordance with the BPEC installer and location of ancillary components, including those Type used for fire safety and acoustic purposes. Designed airflow-balancing figures for the system. or other suitable scheme acceptable to NHBC. or other suitable scheme acceptable to „ „ „ c) „ „ „

Section 3 of the Technical Handbooks, Domestic Ventilation Guide in Scotland and Guide in Scotland and Handbooks, Domestic Ventilation Section 3 of the Technical Also see: Chapter 2.1, Approved Document F, Domestic Ventilation Compliance Guide, Ventilation Domestic Approved Document F, Also see: Chapter 2.1, Wall or ceiling mounted fittings used mounted fittings used or ceiling Wall rate of air between to balance the flow to as grilles. rooms; may be referred fan unit and Carries air from the atmosphere. exhausts it to the external external atmosphere Carries air from the to the MVHR fan unit. fan(s), Unit that contains the filter(s). heat exchanger and the air valves and Carries air between the MVHR fan unit. of the building to Located on the outside finish the intake and exhaust ductwork. Building integration Building Compliance

8.3CHAPTER Mechanical ventilation with heat recovery heat with ventilation Mechanical

fixing of fan units Type and spacing of clips and fixings. Type Location of all ductwork runs, the fan unit and controls. size and position of ducts and terminals. Type, ductwork. Direction of fall for ‘horizontal’ competent and familiar with the system being installed, and competent and familiar with the system „ „ „ „ „ Exhaust ductwork Intake ductwork MVHR fan unit Service ductwork extract and supply fittings Terminal Air valve (extract and supply) MVHR fan units should only be fixed to parts of the building capable of taking the load. Where MVHR fan units are supported by MVHR fan units should only be fixed to parts of the building capable of taking provide a secure fixing point. framed structures, additional components such as noggings may be required to using the clips, brackets and fixings Fan units should be located, orientated and fixed in accordance with the design, recommended by the manufacturer. Proprietary roof terminals should be used to ensure the weathertightness of the roof covering. Proprietary roof terminals should be used to ensure the weathertightness of the Fixing of fan units a) weathertightness b) Weathertightness MVHR systems shall ensure compatibility with other building elements and not adversely affect the MVHR systems shall ensure compatibility with other building elements performance of the building. Issues to be taken into account include: 8.3.3 building regulations will generally be acceptable. MVHR systems should be installed by operatives: Designs and specifications should be issued to site supervisors, relevant specialist subcontractors and suppliers, and include the to site supervisors, relevant specialist subcontractors and suppliers, and Designs and specifications should be issued following information: Provision of information of Provision 8.3.2 be produced in a clearly understandable format, include all relevant Designs and specifications shall the appropriate personnel. information and be distributed to MVHR systems that comply with the guidance in this chapter and are in accordance with the relevant British Standards and in this chapter and are in accordance with the relevant British Standards MVHR systems that comply with the guidance MVHR design, materials and sitework shall comply with the Technical Requirements, and be installed by Requirements, and be installed shall comply with the Technical MVHR design, materials and sitework competent operatives. 8.3.1 Definitions for this chapter for Definitions „ „ „ „ „ 1

1 8.3 „ „ „ „ „ „ Relevant standardsinclude: Proprietary firecomponentsshouldbesuitablytested,andspecifiedtotakeaccountofthetestconditions. finish areusedforairtransfer, the guidance inChapter9.1‘A consistentapproachtofinishes’ shouldbeconsidered. Allowance shouldbemadeforairtransferwithinthehome. Wheregapsbetweentheundersideofinternaldoorsandfloor and datasuppliedbytheductmanufacturer. Ductworkshouldbeasdirectpossibletoreduce thenumberofbends. Airflow resistanceshouldbecalculatedusingfiguresforair valvesandterminalsdeterminedinaccordancewithBSEN13141-2 The MVHRsystemshouldnotadverselyaffect thefireperformanceofbuilding.Issuestobetakenintoaccountinclude: Firestopping Issues thatshouldbetakenintoaccountinclude: approved bythedesigner. recommendations.Variationsmanufacturer’s fromthedesign shouldmaintainthesatisfactoryperformanceofsystemandbe The MVHRsystemshouldbedesignedtoprovidesatisfactoryperformanceandinstalledaccordingthedesign Performance c) b) a) performance account include: MVHR systemsshallensurecompatibilityandsatisfactoryperformance.Issuestobetakeninto 8.3.5 Design considerations account include: along ductwork,ashortlengthofflexibleductcanbeinstalledadjacenttoairvalvesandfanunits.Otherissues takeninto Ductwork shouldbesizedtoallowairpassfreelywithoutcausingexcessivenoisedisturbance. full speedcanreduceunnecessarynoise. noise andvibrationintoaccount.SpecifyingMVHRfanunitsthatcanprovidetherequiredairflowrateswhenrunningatlessthan MVHR fanunitsshouldbesizedtorunattheiroptimumspeedandprovidesuitableperformancewhilsttakingtheresulting MVHR systemsshallbedesignedtominimisedisturbancecausedbynoise. 8.3.4 Particular considerationshould begivenwherecomponentsfromdif and materials,toensurecompatibility andtheperformancerequirementsofsystem. The MVHRsystemshouldbe designedasacompletepackage,takingintoaccountthe performance ofallcomponents Systemised approach BS EN1366-3 BS EN1365-2 BS 476 „ „ „ „ „ „ the system fan capacity, accountingforairflow resistanceof regulations andstandards ventilation ratesassetoutinappropriatebuilding external noise noise betweenhabitablerooms elements ofthebuilding suitable detailingofcomponentspassingthroughother accordance withrelevantbuildingregulations ensuring thatthefirerequirementsofbuildingarein type andpositionofairvalvesterminals systemised approach Noise ‘Fire resistancetestsforserviceinstallations.Penetrationseals.’ ‘Fire resistancetestsforloadbearingelements.Floorsandroofs.’ ‘Fire testsonbuildingmaterialsandstructures.’ Mechanical ventilation withheat recovery

„ „ „ „ „ „ e) d) „ „ „ „ „ „ ferent manufacturersarespecified onthesamesystem. integrity ofwallsandfloors. integrity ofprotectedstairsandhalls location andtypeoffirestopstobeused airflow resistance,includingfrombendsandfittings. ensuring theevendistributionofairflow, takingintoaccount the typeofmountingsusedtosecureMVHRfanunit. location oftheMVHRfanunit protection fromcold. control ofcondensation CHAPTER 8.3 To reducenoisetransfer Also see:Chapter9.1

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2 2 8.3

2020

(1) Yes Yes Yes Ductwork located outside the insulated part of the home insulation of ductwork and other system components. installed in a neat and workmanlike manner to ensure that installed in a neat and workmanlike manner there are no gaps installed in accordance with the manufacturer’s recommendations. the velocity of the system. the velocity for the likely location of tall furniture positioned to account over beds and seating areas and to avoid draughts lockable, where adjustable. biomass or solid fuel chimney terminal. insulated the within are that spaces through air cold carrying parts of the home. „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „

Yes No Yes Ductwork continuously insulated Ductwork located inside the insulated part of the home Ductwork insulation

8.3CHAPTER Mechanical ventilation with heat recovery heat with ventilation Mechanical

Additional insulation should be provided to protect the system from the cold. performance in relation to indoor air quality the manufacturer’s recommendations where any parts are located outside the insulated part of the home inert, durable and suitable for use with the ductwork system inert, durable and suitable for use with the continuous and vapour resistant by moisture vapour not adversely affected it passes through spaces outside the insulated parts of it passes through spaces outside the insulated on a wall soil and vent pipe terminal boiler flue outlet the home, such as a roof void a maximum of 400mm from the ceiling, where located a maximum of 400mm (on plan) from hobs in kitchens a minimum of 600mm positioned on the opposite side of the room from internal positioned on the opposite door openings from walls, where located on a ceiling a minimum of 200mm supply or extract function wall or ceiling location wall or ceiling „ „ „ „ „ „ „ „ „ „ „ „ „ „ Exhaust Service (supply and extract) Intake Type of duct Type Protection from cold of cold. Issues to be taken into account include: MVHR systems should be protected from the effects Any condensate that forms within the fan unit or ductwork should be able to drain to a suitable outfall. Fan units should be Any condensate that forms within the fan unit or ductwork should be able to drain via a dry trap. located to enable connection of the condensate drain to the soil and waste system Notes 1 Table 1: Table Ductwork should be insulated to prevent condensation formation where: Ductwork should be insulated to prevent Control of condensation Type and position of air valves and terminals air valves and and position of Type for: appropriate specification and function, ensuring according to location should be selected Air valves To prevent damage to the components and ensure satisfactory operation, MVHR systems should be fitted with automatic prevent damage to the components and ensure satisfactory operation, MVHR systems should be fitted with To Where a vapour control layer is incorporated, the joints should be sealed using appropriate tapes or sealants as recommended the joints should be sealed using appropriate tapes or sealants as recommended Where a vapour control layer is incorporated, by the manufacturer. frost protection. To create cross-ventilation within a room and to ensure satisfactory operation, air valves on low velocity systems should be: satisfactory operation, air valves on within a room and to ensure create cross-ventilation To terminals and other potential generally be separated from exhaust intake terminals should prevent cross-contamination, To the intake measured on plan. Increased separation distances may be required between sources of pollution by a minimum of 1m and any: should prevent the entry of birds and animals. Terminals pre-insulated ductwork, or a proprietary insulation system with a thermal resistance This can be achieved by using suitable material, with a thermal conductivity of 0.04W/Mk. equivalent to a minimum of 25mm of insulating for proprietary duct insulation systems and pre-insulated ducts should be: Ductwork insulation, including that used „ „ „ „ „ „ „ „ „ „ „ „ „ „ 3

3 8.3 „ „ „ „ „ „ recommendations orinaccordancewith Technical Requirement R5. Where ductworkroutesrequirealterationstostructuralelements, theseshouldbeinaccordancewiththemanufacturer a) account include: MVHR ductworkandinsulation shallbeinstalledtoasatisfactorystandard. Issuestobetakeninto 8.3.8 Fixingandjointing of ductwork Flexible ductingshould: Bends, connectionsandjunctionsshouldbeformedusing proprietary componentsthatarepartoftheductworksystem. Ductwork should: affect theperformanceofbuilding. Ductwork designandthematerialsusedshouldbesuitableforintendedpurposenotadversely 8.3.7 Table 2: easily accessible. MVHR systemsshallbedesignedandinstalledtoensurethatthefanunitassociatedcontrolsare 8.3.6 Access andoperation home shouldbeinsulatedtopreventfreezing. Condensate drainslocatedoutsidetheinsulatedpartof of horizontalinsulation. achieved byinstallingtheductworkbetweenlayers with athermalconductivityof0.04W/Mk. This maybe resistance equivalenttoatleast150mmofinsulatingmaterial parts ofthehome,shouldbeinsulatedtoachieveathermal Horizontal sectionsofserviceductwork,outsidetheinsulated Access Cleaning and controls Indication functionality Control and „ „ „ „ „ „ not bemorethan300mminlength only belocatedadjacenttofanunitsorairvalves recommendations. be fixedinaccordancewiththemanufacturer’s systems be ofarigidorsemi-rigidmaterialsuitableforuseinMVHR be routedasdirectlypracticable provide satisfactoryperformanceforthelifeofsystem fixing Ductwork Guidance forthesuitablefunctioningof,andaccessto,MVHRsystem the home Fan unitlocatedinsidetheinsulatedpartof carried out. be locatedandsizedtoenableroutineservicing Access shouldnotbeobstructedandpanels or ductworkshouldbeaccessibleforcleaning. To maintainoperatingperformance,extractserviceductworkandairvalvesshouldeitherbefittedwithfilters, and besimpletouse. of operation. These shouldbevisiblefromwithintheinsulatedenvelope,notobscuredview, MVHR systemsshouldincludevisualindicatorsshowingmaintenanceandservicingrequirements,mode around theheatexchanger. The MVHRsystemshouldbecapableofbeingisolatedbyaswitchedfusedspur. it serves.Wherea‘summerbypass’ functionisprovided,itshouldoperateautomaticallyanddiverttheairflow Where a‘boost’ functionisprovided,itshouldswitchoff automaticallyandbelocatedin,oradjacentto,theroom Mechanical ventilation withheat recovery

„ b) „ not beusedtoformbends. jointing. the home Fan unitlocatedoutsidetheinsulatedpartof designed totakeaccountoftheadditionalload. any insulation,andthesupportingstructureshouldbe platform shouldbedesignedtoensurethecontinuityof MVHR fanunit,shouldbeprovided. The walkwayand and aworkingplatform1m A safemeansofaccess,includingasuitablewalkway a thermalconductivityof0.04W/Mk equivalent toatleast150mmofinsulatingmaterialwith loft insulationusedtoachieveatotalthermalperformance conductivity of0.04W/Mk of insulatingmaterialwithathermal performance equivalenttoatleast25mm pre-insulated toachieveathermal air valve CHAPTER 8.3 2 immediatelyadjacenttothe

2020

’s

4 4 8.3

, and be: 2020

. . Adjusting the fan speed above the designed output may . for consumables guidance for the use of summer bypass and boost settings, where installed contact details of the manufacturer and installer details of the installed system, including part numbers details of any maintenance and servicing agreements. should be adjusted by using the air valves and controls to should be adjusted by using the air valves achieve the correct balancing and airflow rates should have air valves locked in position after correct commissioning and balancing. sealed with purpose-designed connections in accordance sealed with purpose-designed connections with the manufacturer’s recommendations. temperature compatibility with the duct material. „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „

Commissioning and balancing Commissioning 8.3CHAPTER Mechanical ventilation with heat recovery heat with ventilation Mechanical

method of cleaning the ductwork, where required details of routine maintenance, e.g. changing/cleaning the filters the commissioning certificate user instructions for the system and its controls user-friendly description and explanation of the system, including the location of components should be commissioned to confirm performance including ductwork and filters, should be checked to ensure including ductwork and filters, should be it is clear from dirt and dust that may have accumulated during construction moisture thermal movement durable and airtight securely fixed „ „ „ „ „ „ „ „ „ „ „ MVHR systems shall be provided with clear and detailed information and instructions that are handed over MVHR systems shall be provided with clear and detailed information to the end user. and include: The pack of information should be in a format intended for a non-technical user Handover requirements Handover 8.3.10 Upon completion of the installation MVHR systems should be protected from dust during the construction of the home. Where systems should be protected from dust during the construction of the home. Upon completion of the installation MVHR covers applied to air valves. and dust off possible the system should be switched Prior to completion of the home, the system: 8.3.9 shall be tested and commissioned in accordance with the MVHR design, materials and sitework commissioning schedule. Jointing ductwork should be specified by the duct manufacturer The method and materials used for jointing Parallel ductwork runs should be positioned to maintain a reasonably even gap. should be positioned to maintain a reasonably Parallel ductwork runs with the design, and installed should be to a suitable outfall in accordance collecting, horizontal ductwork prevent condensate To localised dips. to a true line to avoid to prevent water entering be positioned to slope slightly outwards through an external wall, it should Where ductwork passes Ductwork should be securely installed in a neat and workmanlike manner installed in a neat and should be securely Ductwork Fixing the building. in accordance with the clips no more than 750mm apart, or securely held in position by evenly spaced Ductwork should be ductwork manufacturer’s recommendations. transfer noise to the home. such as plasterboard ceilings, that may be in direct contact with other surfaces, Ductwork should not Where the system cannot be balanced using the air valves and system controls, the complete system should be checked to Where the system cannot be balanced using the air valves and system controls, ensure that it complies with the design. Any changes from the design should be referred back to the designer result in noise disturbance, and should be avoided. copy of the commissioning certificate should be made available to NHBC upon request. A Where tapes and sealants are used, they should be suitable for the intended purpose and be recommended by the Where tapes and sealants are used, they to be taken into account in relation to the durability of the jointing method include: Issues ductwork manufacturer. be dry and free from grease and dust and surfaces should should be installed in a neat and workmanlike manner, Tape not extrude to the inside of the duct. before applying. Excess sealant should „ „ „ „ „ „ „ „ „ „ „ 5

5 8.3 A consistent approach to finishes CHAPTER 9.1

This chapter gives guidance on meeting the Technical Requirements for finishes in new homes.

9.1.1 Compliance 01 9.1.2 External walls 01 9.1.3 Internal walls and ceilings 04 9.1.4 Doors and windows 05 9.1.5 Floors 07 9.1.6 Glazing 07 9.1.7 Ceramic, concrete, terrazzo and similar tile finishes 07 9.1.8 Fitted furniture 07 9.1.9 Joint sealants 08 9.1.10 Paint finishes 08 9.1.11 Sanitary ware 08 9.1.12 Other surfaces and components 09 9.1.13 Pitched roof coverings 09 9.1.14 Garages 09 9.1.15 External works 09

.

Also see: Chapter 2.1 Also see: Also see: Chapter 6.11

2020 brick slip cladding timber cladding tile hanging cast stone elements. Some minor shrinkage cracking may occur between masonry units (bricks and blocks) and mortar joints. in daylight, and from a minimum distance of 10m. in daylight, and from a minimum distance not have significant cracks in the facing bricks or other damage, such as chips and marks greater than 15mm Some brick products have features or marks which may be in excess of 15mm in diameter. uses tolerances and finishes considered to be appropriate finishes considered to be appropriate uses tolerances and industry and takes precedence over for the house-building other recommendations with every situation which may arise, is not intended to deal be exercised. and discretion should in diameter.

„ „ „ „ „ „ e) f) g) h) „ „ „ „ „ „

CHAPTER 9.1 A consistent approach to finishes to approach consistent A

Compliance

fairfaced masonry render curtain walling rainscreen cladding Efflorescence occurs naturally in some types of masonry. It Efflorescence occurs naturally in some types of masonry. is not harmful and generally disappears over time. Some mortar blemishes will occur on individual Some variation will occur in the texture, finish and colour of in individual masonry units and generally over mortar, be reasonably uniform in texture, finish and colour, be reasonably uniform in texture, finish and colour, including mortar not have excessive colour banding masonry units. the wall. for the entire wall (e.g. panels and interfaces), and not for the entire wall (e.g. panels and interfaces), for the individual elements of the construction, such as individual bricks, individual bed joints, or design features and details (e.g. quoins, soldier courses and plinths) should be considered in conjunction with relevant should be considered and guidance contained elsewhere performance standards within NHBC Standards is intended to apply when the home is substantially complete when the home is substantially complete is intended to apply pre-handover inspection and ready for NHBC both during the construction process will be used by NHBC resolutions under section 2 of the and when conducting cover Buildmark insurance „ „ „ „ „ „ „ „ „ Fairfaced masonry Fairfaced masonry should: is inevitable; this is often used as an aesthetic feature and should be recognised in appropriate tolerances or considered feature and should be recognised in appropriate tolerances or considered is inevitable; this is often used as an aesthetic will be in the opinion of NHBC. Acceptability of finished appearances separately. to remedy minor variations from the tolerances and finishes given should be The nature and extent of work necessary part of the for example, how readily visible or extensive the affected proportionate and appropriate to the circumstances: construction is. External walls External 9.1.2 finished appearance. Issues to be taken into account include: External walls shall have an acceptable a) b) c) d) Some elements may be subject to the effects of normal thermal or drying movement, and this may occur both before and of normal thermal or drying Some elements may be subject to the effects after completion. variation not intended to be; this includes reclaimed materials. Some colour and texture Some materials are not uniform and are Finishes that comply with the guidance in this chapter will generally be acceptable. with the guidance in this chapter will generally Finishes that comply This guidance: 9.1.1 Requirements. the Technical shall comply with Finishes Tolerances and appearance should be considered: Tolerances Where a fairfaced finish can only be achieved on one side (such as half brick walls), the other faces should be left neat and tidy Where a fairfaced finish can only be achieved on one side (such as half brick Also note: „ „ „ „ „ „ „ „ „ 1

1 9.1 kept clearofthewallface. dimensions shouldensurethereferencelineis Spacing blockdimensionsareaguide,andfinal line shouldbe17-33mmfromthereference Using 25mmwidespacingblocks,themasonry Example: height storey „ „ „ „ „ „ ± average ofthenexteightsuccessivejointsbyamaximum The thicknessofanindividualbedjointshouldnotvaryfromthe Also note: should generallybewithin Perpend jointsshouldnotcumulatively displaceinthesamedirectionformorethan5joints. The centre lineofanyperpendjoint Therefore, theacceptablerangeofbedjointbelow 8 measuredbedjointsis9-12mm. Divide by8=10.5mm 11+10+12+10+11+9+11+10 =84 Measure andadd8successivebedjointsdividebyto determinetheaveragesize: Example ofhowtodetermineifbedjointthickness isacceptable top ofagivenrowbricks,with: Bed jointsshouldbereasonablystraight,measuredalongthe Fairfaced masonryshouldmeetthefollowingtolerances: 1.5mm. „ „ „ „ „ „ not cumulatively displace. panels aboveand below. The jointswithinthepanelshould between openingsmaybeoffset withtheperpjointsin to achievesettingout,perpjoints inmasonrypanels section ofwall. a maximumdeviationfromstraightnessof±8mminany5m a maximumdeviationof4mmover1matexternalreveals. storey and12mmintotal Taller wallsshouldbeamaximumof8mmfromplumbper a maximumof8mmfromplumbinanystoreyupto3m. storey height(upto3m) adequately straightinsection,withatoleranceof±8mmper deviation inanylengthofwallupto5m adequately straightonplan,witha±8mmmaximum straight insection

with max.8mmdeviation nominal lineofwall reference line 25x25mm spacingbloc masonry line ±15mm ofthecentreline next 5successiveperpendjoints.

k

.

storey height should ensuretheplumblineiskeptclearofwallface Spacing blockdimensionsareaguide,andfinal Note: the spacingblock. 42-58mm fromthewall,measuredatbetween2.5-3m Using 50mmwidespacingblocks,theplumbbobshouldbe Example: plumb insection A consistent approach to finishes plumb line 50x50mm spacingbloc

line masonry reference line ensure thereferencelineiskeptclearofwallface. Spacing blockdimensionsareaguide,andfinalshould 17-33mm fromthereferenceline Using 25mmwidespacingblocks,themasonrylineshouldbe Example: spacing bloc 25x25m k deviation max. m k . Straightness ofbedjoints

the straightnessofbedjoint no frequentvariationsin straightness inplan line reference 9.1 CHAPTER straight atreveals 5m 5m . deviation max. from referenceline deviation (17-33mm with max.±8mm nominal lineofwall deviation max. 4mm s 1m straightedg

2020 )

e 2 2 9.1

. equal spacing blocks reference line nominal line of wall with max. ±4mm deviation straightness in section 5m dimensions should ensure the plumb line is kept clear of the wall face. Example: Using 25mm wide spacing blocks, the masonry line should be 21-29mm from the reference line Spacing block dimensions are a guide, and final Tiles should not have significant variations in should not have significant variations Tiles 2020 the design. Surface abrasions and chips should be repaired in accordance with the manufacturer’s recommendations. a maximum deviation of ±2mm in any storey height or a maximum deviation of ±2mm in any storey unless otherwise structural bay width, and ±5mm overall, specified in the design. height or a maximum deviation of ±3mm in any storey structural bay width, unless otherwise specified in

„ „ „ „ „ „

CHAPTER 9.1 A consistent approach to finishes to approach consistent A

Efflorescence, fungal growth and colour variation may occur due to orientation, shading and pollution. The effects of normal weathering may cause certain The effects over time, to develop a silver/grey colour. uncoated timber, reasonable tolerances and appearance for the materials reasonable tolerances and appearance

reasonable tolerances and appearance for the materials reasonable tolerances and appearance Areas of render in close proximity to features (e.g. bell casts) Areas of render in close proximity to features are excluded from the tolerance. straightness and Flatness is measured in a similar way to plumb of masonry. Daywork joints, patching and other repairs may be visible Daywork joints, patching but should not be unduly obtrusive. to occur in both Some localised hairline cracking is likely systems. Such traditional render and proprietary render the performance of cracking and crazing should not impair the home. There may be some colour variation in appearance due to There may be some background and orientation in suction of the differences be free from crazing (a set of hairline cracks, generally less (a set of hairline cracks, generally less be free from crazing no more than 0.2mm wide). than 1mm in depth and be reasonably consistent in texture, finish and colour be reasonably consistent ±4mm vertical and horizontal be flat, within a maximum deviation in 5m of the wall. „ „ „ „ „ „ „ „ „ „ „ „ texture, finish and colour. See Clause 9.1.13. texture, finish and colour. Cast stone elements Cast stone should be reasonably uniform in both colour and texture. Also note: Panels should be reasonably uniform in appearance, particularly at abutments. Panels should be reasonably uniform in appearance, particularly at abutments. Tile hanging Tile Variation in colour may occur in uncoated timber exposed to the weather, and the rate and extent may vary. and the rate and extent may in colour may occur in uncoated timber exposed to the weather, Variation Also note: Brick slip cladding should meet the same tolerances as fairfaced masonry. cladding Timber Brick slip cladding Rainscreen cladding should be within: Rainscreen cladding Curtain walling should be within: Curtain walling Render Render should: Also note: „ „ „ „ „ „ „ „ „ „ „ „ 3

3 9.1 „ „ „ „ „ „ „ „ „ Ceilings shouldbe: Ceilings Walls should: Walls Plastered anddrylinedsurfacesshould: Plastering anddrylining b) a) appearance. Issuestobetakenintoaccountinclude: Internal wallsandceilingsshallbebuilttoappropriatetoleranceshaveanacceptablefinished 9.1.3 „ „ „ „ „ „ „ „ „ edge withequaloffsets. flat withina±5mmdeviation,measuredusing2mstraight a maximumof20mmoutlevelforceilingsover6macross of theceiling) across (measuredatthefurthestpointsfullwidth level withina3mmdeviationper1mforceilingsupto6m storey and12mmintotal. Taller wallsshouldbeamaximumof8mmfromplumbper be amaximumof8mmfromplumbforwallsupto3mhigh. a 2mstraightedgewithequaloffsets have flatwallsandwithina±3mmdeviationmeasuredusing finished surface have jointingtapefullycoveredandunobtrusiveinthe (e.g. aroundswitchplates) have novisiblegapsbetweenfittingsandthesurface textural differences aroundlightsandotherfittings be reasonablyuniform,althoughtheremayminor straight edgewithequaloffsets maximum ±3mmdeviation,measuredusinga450mm not haveboardjointsreadilyvisibleandbewithina walls andceilings plastering anddrylining Internal walls andceilings A consistent approach to finishes

„ c)

„ uplighters shouldbeswitchedoff. no artificiallightshiningonthesurface. Wall lightsand/or be viewedfromadistanceof2minnaturaldaylightwith

skirtings. (applies inalldirections with equalof from a2mstraightedge max. ±3mmdeviation flatness ofwallfinish: straight edgewithequalof ±5mm max.deviationusinga2m measured betweenthefurthestpoint fsets flatness ofceiling level ofceiling )

9.1 CHAPTER fsets deviation per1m max. 3mm

s greater than3m in acontinuouswallheight max. 12mmoutofplumb up to3m in astoreyheightof max. 8mmoutofplumb plumb ofwallfinish:

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4 4 9.1 m

m ±5mm max. deviation in 250m

±5mm max. deviation in 250m max. 10mm 2020 5mm when larger. joints should present a continuous appearance when viewed joints should present a continuous appearance initial shrinkage of from a distance of 2m in daylight (some of the skirting may already be evident at completion the property). Gaps may appear at joints and corners due to shrinkage, and between the wall finish and skirting due to drying out, shrinkage and fixing position. be level within 3mm across the sill measured from the frame (tiled sills, in bathrooms, for example, may be intentionally laid sloping away from the window) of with a maximum deviation be square with the window, ±5mm for reveals up to 250mm deep. provided with an appropriate decorative finish. an appropriate provided with which pass across Small cracks may occur in wall finishes floors (e.g. in staircase walls). of up to 4mm may Where stair strings abut a wall, a crack appear as a result of shrinkage of materials.

„ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „

±10mm max. deviation in 500mm

max. 10mm Doors and windows Doors CHAPTER 9.1 A consistent approach to finishes to approach consistent A

3mm when up to 1.5m in height have plumb reveals, a maximum of 3mm from plumb for openings up to 1.5m high, and 5mm where higher be flat along the length of sills and window boards, with a maximum deviation of ±3mm in every 2m have level heads and sills, a maximum of 3mm from level for openings up to 1.5m, and 5mm where longer The gap between the floor finish and the skirting may increase due to normal drying out, shrinkage and/or deflection, particularly in timber floors. be visible. coverings) and the the gap between the floor finish (without 5mm at the time bottom of the skirting should not exceed of completion Some cracking (up to 2mm wide) may occur at wall, floor Some cracking (up to 2mm wide) may occur and differential and ceiling junctions, due to shrinkage movement of materials. In plastered walls and ceilings, some tooling marks may In plastered walls and ceilings, some tooling square neat and tidy lerances for corner details „ „ „ „ „ „ „ „ „ „ Also note: To Window frames should not be distorted in the opening, and a maximum from plumb of: Window frames should not be distorted in the opening, and a maximum from plumb Internal openings in walls should: 9.1.4 openings in walls and external Doors and windows shall be installed to appropriate tolerances, including openings viewed from the inside. Skirtings Where skirtings are installed: ±10mm max. deviation from square in 500mm Setting out of corners, duct casings, access covers and any associated framing should be: framing should be: and any associated access covers of corners, duct casings, Setting out Also note: „ „ „ „ „ „ „ „ „ „ 5

5 9.1 „ „ „ „ „ prejudice tosatisfactoryperformanceforventilationandfireresistance. recommendations. The tolerancesinthisclausearewithout Fire doorsshouldbeinstalledinaccordancewiththemanufacturer’s Fire doors the opening,and: Internal doorsandframesshouldalwaysbeinstalledinaccordancewiththemanufacturer Internal doors opening, and: recommendations,notbedistortedinthe External doorsandframesshouldbeinstalledinaccordance withthemanufacturer’s External doors „ „ „ „ „ frame andnotbeoutofplumbintwodirections frames shouldbewithin5mmofplumbovertheheight when determiningthegapbeneathinternaldoors. requirements forthebuildingneedtobetakenintoaccount floor shouldtobetween10mmand22mm. Theventilation the gapbetweenundersideofdoorandunfinished 5mm inheight,and3mmwidth distortion acrossdoorsshouldbelimitedtoamaximumof stiles shouldbewithin4mm)anduniform maximum of4mm(fordoubledoors,thegapatmeeting the gapbetweendoorandheadorjambshouldbea frame andnotoutofplumbintwodirections frames shouldbewithin5mmofplumbovertheheight the window laid slopingawayfro example, maybeintentionally *tiled sills,inbathrooms,fo for openingsover1.5mhigh max. 5mmoutofplumb for openingsupto1.5mhigh reveals: max.3mmoutofplumb reveal (measuredfromframe) max. 3mmoutoflevelacross 250mm deep square forrevealsupto ± 5mmmax.deviationof openings over1.5mwide max. 5mmoutoflevelfor 1.5m wide level foropeningsupto head andsill:max.3mmoutof To lerances forinternalopenings ±5mm deviationofsquareintorevealupto250mmdeep 5mm m

r *

window boards length ofsillsand flatness along deviation in2m ±3mm max. 5mm

A consistent approach to finishes „ „ of 5mminheightand3mmwidth. distortion acrossthedoorshouldbelimitedtoamaximum in termsofweathertightness,draughtexclusionandfireresistanc the dimensionsarewithoutprejudicetosatisfactoryperformance The max.gapshouldnotexceed22mm,howeve floor finish(fora760mmwidedoor) should beagapof10mmbetweenthebottomdooran In EnglandandW accordingly will needtochooseacoveringsuitoradjustthedoorheigh the opening be distortedin frames shouldnot over 1.5mhig plumb forwindows max. 5mmoutof less than1.5mhigh plumb forwindows max. 3mmoutof window distortion: To across height max. 5mm across width max. 3mm door distortion: in theopening not bedistorted frames should lerances forwindows . h ales, wherethebuilderprovidesafloorfinishthere

(in onedirectiononly over heightofframe max. 5mmoutofplumb ’s recommendations,notbedistortedin 9.1 CHAPTER should be10-22mm door andunfinishedfloor underside ofaninterna the gapbetweenth ) should bemax.4mm gap atthemeetingstile for doubledoorsth should beused recommendation manufacture (for firedoorsthe door andheadorjam max. 4mmgapbetween r, homeowners e

2020 r’ l d s t ; s e e b

s

6 6 9.1

The selection of floor finish The selection of floor ferences in level between the floor and duct cover, the floor and duct cover, ferences in level between 2020 should limit the effect of dimensional irregularities, with joints should limit the effect appearance suitably arranged to maintain a regular within ±3mm the variation in surface level should be equal offsets measured using a 2m straight edge with tiles should the variation in surface level between adjacent 6mm wide, or 2mm be 1mm or less where the joint is up to or less where the joint is over 6mm wide. have uniform gaps between adjacent doors and/or drawers where appropriate not have conspicuous abrasions or scratches on a distance of 0.5m. a maximum of 20mm out of level for floors over 6m across a maximum of 20mm deviation, measured using a 2m straight flat within a ±5mm edge with equal offsets. fine scratches not more than 25mm long minute particles. factory-finished components when viewed in daylight from

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„ „ „ „ „ „ „ „ „

Ceramic, concrete, terrazzo and similar tile finishes terrazzo concrete, Ceramic, CHAPTER 9.1 A consistent approach to finishes to approach consistent A

and there should not be significant differences in level at the and there should not be significant differences intersection of adjacent worktops operate as intended by the manufacturer be visually aligned (vertically, horizontally and in plan), be visually aligned (vertically, joints in floor tiles should generally not exceed the tile thickness, although wider joints up to 10mm may be necessary to accommodate dimensional irregularities in some tiles floor tile joints should be a minimum of 3mm and floor tile joints should be a minimum of otherwise proportionally wider for larger tiles, unless specified by the manufacturer wall tile joints should be a minimum of 1.5mm for ceramic wall tile joints should be a minimum of 1.5mm and 6mm for tiles, 2mm for smooth natural stone tiles textured tiles joints should be straight and in alignment, unless the tiles joints should be straight and in alignment, are, by design, irregular in shape hairlines or blobs bubbles or blisters level within a 3mm deviation per 1m for floors up to 6m level within a 3mm deviation the furthest points across the full width across (measured at of the floor) „ „ „ „ „ „ „ „ „ Fitted furniture, including doors and drawers, should: Fitted furniture Fitted 9.1.8 Fitted furniture shall have an appropriate appearance. For ceramic, concrete, terrazzo and similar tile finishes: For ceramic, concrete, terrazzo and similar 9.1.7 tile finishes shall have an appropriate appearance. Ceramic, concrete, terrazzo and similar The above does not apply to areas within 6mm of the edge of the pane, where minor scratching may occur. The above does not apply to areas within Glass should be checked in daylight, from within the room and from a minimum distance of 2m (3m for toughened, laminated or within the room and from a minimum distance of 2m (3m for toughened, laminated Glass should be checked in daylight, from The following are acceptable where they are not obtrusive or bunched: coated glass). Glazing 9.1.6 Glass shall be free from undue defects. should take into account that drying shrinkage of the floor may result in minor dif that drying shrinkage of the floor should take into account evident with some types of thin floor coverings. which may be more Underfloor service ducts should be constructed so that the cover is level with the adjacent floor finish. cover is level with the adjacent floor ducts should be constructed so that the Underfloor service Floors should be: Floors 9.1.5 tolerances. be built to appropriate Floors shall „ „ „ „ „ „ „ „ „ 7

7 9.1 „ „ „ „ „ „ „ „ „ „ „ Also note: in daylightfromadistanceof0.5m. abrasions, scratchesorchipswhenviewed Sanitary fittings,suchasbaths,showertraysandbasins,shouldnothaveconspicuous handover. Baths, showertraysandbasinsshallbefreefrom scratches,chipsandotherdamageatthetimeof 9.1.11 Painted andvarnishedsurfacesshould: brush marks. Painted andvarnishedsurfacesshallbeeveninappearancefreefromconspicuousruns prominent 9.1.10 Sealants shouldbetooledto: Joint sealantsshallhaveaneatandtidyappearance. 9.1.9 Also note: Also note: Also note: „ „ „ „ „ „ „ „ „ „ „ outlets andnotfromportable equipment. should beviewedinartificial light fromfixedwallorceiling In roomsorareaswherethere isnodaylight,scratches variations mayoccur. Where paintedsurfacesaretouchedup,minorcolour woodwork. paint finish,particularlywherejointsoccurinplasterand Drying shrinkageoftimbermaycausecrackingthe colour andtexturemayalsovary. Timber surfaces mayshowlimitedraisedgrain,andthe lights and/oruplightersshouldbeswitchedoff. 2m andnotbyshiningartificiallightonthesurface. Wall Surfaces shouldbeviewedindaylightfromadistanceof and splits be reasonablysmoothandfreefromnailholes,cracks baths maymakethisimpossible). possible, dependingonthelocation(e.g.showersand Joints shouldbeviewedfromadistanceof2m,where remove blistersandirregularities Fitted furnitureshouldbeviewedfromadistanceof0.5m. be unavoidable. products, areinevitableandsmalldifferences inheightmay and becauseminorvariations,evenwithmanufactured adjacent worktopsduetothevarietyofmaterialsavailable No dimensionaltolerancehasbeensetfortheabutmentof adjustments aspartofthefittingprocess. because somevariationwillbenecessarytotakeaccountof adjacent doorsand/ordrawersorfortheiralignment, No dimensionaltolerancehasbeensetforgapsbetween Joint sealants Sanitary ware Paint finishes

A consistent approach to finishes

„ „ „ „ „ „ „ „ „

„ „ „ „ „ „ „ „ „ achieve acompact,smoothneatsurfacefinish. near hobsandextractorfans. Kitchen unitsshouldnotdelaminate,includingthoselocated outlets andnotfromportableequipment. should beviewedinartificiallightfromfixedwallorceiling In roomsorareaswherethereisnodaylight,scratches respraying orpaintingasappropriate. recommendations, whichmayincludefilling,polishingout, should beremovedinaccordancewiththemanufacturer’s Conspicuous surfaceabrasionscausedduringinstallation components, suchasdoors. have adifferent finishedappearancefromfactory-finished Site-decorated trim,suchasarchitraveandskirting,may to limitthis. a compound contain primers modern even though paintwork, Resin canexudefromknots,causingdiscolorationof of factorssuchasexposuretosunlight,rainandpollutants. External finisheswilldullovertime,dependingonanumber be reasonablyuniformincolour, textureandfinish. have jointsfilled

9.1 CHAPTER

2020

8 8 9.1

2020 be positioned so that the difference in height between be positioned so that the difference the cover and adjacent hard surfaces allows for future settlement. Garage floors may be installed with falls for drainage orGarage floors may be installed with falls not been sealed,fire separation. Where garage floors have dusting may occur. designed and constructed to minimise the potential for standing water. When checking flatness, the slope required for drainage on drives should be taken into account. be reasonably uniform in colour, texture and finish. in colour, be reasonably uniform banding. be suitably mixed to avoid excessive colour types of tile. It is Efflorescence occurs naturally on some which Tiles time. not harmful and generally disappears over suitably mixed to have efflorescence when laid should be avoid a patchy appearance.

„ „ „ „ „ „ „ „ „ „ „ „ „ „

Garages External works External Pitched roof coverings roof Pitched CHAPTER 9.1 A consistent approach to finishes to approach consistent A

adjacent ground) align with the adjacent ground or surface finish (for channels, the cover should be set below the Displacement and variations in surface levels, including scuffing and pitting, may arise due to settlement, natural ground movement and traffic. within a maximum ±10mm deviation measured using a 2m localised falls into however, straight edge with equal offsets; gulleys and channels are acceptable Cracks up to 2mm wide in unplastered blockwork walls mayCracks up to 2mm wide in unplastered blockwork shrinkage. be evident due to thermal movement and Some minor variations will occur in the texture, finish and Some minor variations will occur in the colour of individual tiles and slates. and splits tiles andSome minor blemishes will occur on individual slates. be reasonably uniform in texture, finish and colour be reasonably uniform in texture, finish have joints filled be reasonably smooth and free from nail holes, cracks be reasonably smooth „ „ „ „ „ „ „ „ „ One hour after rain has stopped, areas of temporary standing water should not be deeper than 5mm or exceed 1m². Temporary Temporary be deeper than 5mm or exceed 1m². One hour after rain has stopped, areas of temporary standing water should not standing water is not permitted adjacent to entrance doors. Also note: Drainage covers should: Also note: Drives and paths should be: 9.1.15 and paths, shall have appropriate finishes. External works, including drives Garage walls, floors and roofs should be built to appropriate tolerances. Garage walls, floors and roofs should Also note: 9.1.14 appearance. Garages shall have an acceptable Tiles and slates should: Tiles 9.1.13 appearance. shall have an acceptable finished Pitched roof coverings Other surfaces and finishes, such as fascia boards, meter cabinets and radiators, should: finishes, such as fascia boards, meter Other surfaces and Other surfaces and components and surfaces Other 9.1.12 appropriate appearance. shall have an and finishes Other surfaces „ „ „ „ „ „ „ „ „ 9

9 9.1 Wall and ceiling finishes CHAPTER 9.2

This chapter gives guidance on meeting the Technical Requirements for internal wall and ceiling finishes.

9.2.1 Compliance 01 9.2.2 Provision of information 01 9.2.3 Plastering 01 9.2.4 Dry lining 02 9.2.5 Ceramic wall tiling 05

’s ’s

Also see: Chapter 2.1 Also see: Also see: Chapter 8.1 Table 1. Table checked to ensure adequate and even suction checked to ensure adequate and even flat plaster finish sufficiently even to provide a reasonably should be avoided). (excessive ‘dubbing out’ Fixing specification. tiled surfaces. Extent and detail of Location of services adjacent to tiled surfaces. „ „ „ „ „ „ „ „ „ „ ‘Specification for uncoated expanded metal carbon steel sheets for ‘Specification for uncoated expanded general purposes’. and test methods’. ‘Metal lath and beads. Definitions, requirements ‘Gypsum binders and gypsum plasters’. emulsion bonding agents for ‘Specification for polyvinyl acetate (PVAC) indoor use with gypsum building plasters’. 2020

Treatment Suitable bonding treatment, hacking, spatterdash, or stipple. May require expanded metal to provide key for plastering and to reduce the movement. of differential effects Plaster should not be stronger than recommended by the blockwork manufacturer. Plastering should be conducted in accordance with the manufacturer recommendations, accounting for the moisture content of the blocks. May require raked joints or the use of keyed bricks. Guidance is contained in BS 8212. BS 405 BS EN 13658-1/2 BS EN 13279 BS 5270-1 Recommended treatments for substrates Materials for use in plastering 9.2 CHAPTER Wall and ceiling finishes ceiling and Wall

suitably finished to provide an adequate key given an appropriate treatment before plastering, given an appropriate treatment before plastering, in accordance with BS 8481 Schedule of finishes. and special requirements. Plaster thickness, mix dry lining. Installation details of vapour checks behind „ „ „ „ „ Metal laths and beads Surface High-density clay, or concrete bricks and High-density clay, blocks and dense concrete (including soffits) Mixed backgrounds, e.g. concrete with bricks/blocks Lightweight concrete blocks Autoclaved aerated concrete blocks Normal clay brickwork and concrete block Plasterboard Plasters The background should be: Table 2: Table Table 1: Table Materials for plastering should be in accordance with BS 8481 and those listed in Materials for plastering should be in accordance 9.2.3 Plastering 9.2.3 substrate for the decorative finish. Plastering shall provide an adequate Designs and specifications should be issued to site supervisors, relevant specialist subcontractors and suppliers, and include the relevant specialist subcontractors should be issued to site supervisors, Designs and specifications following information: sound insulation, overall performance should be in accordance with the fire resistance or contribute to Where plaster is intended to building regulations. Provision of information of Provision 9.2.2 include all relevant a clearly understandable format, shall be produced in Designs and specifications personnel. be distributed to the appropriate information and Wall and ceiling finishes that comply with the guidance in this chapter will generally be acceptable. that comply with the guidance in this and ceiling finishes Wall 9.2.1 Compliance 9.2.1 Technical Requirements. comply with the finishes shall and ceiling Wall Mixed background materials and associated differential movement can lead to cracks and should be avoided. Suitable precautions movement can Mixed background materials and associated differential should be taken, e.g. using metal lathing. fasteners, as recommended by Metal beads should be used to provide edge protection, and be fixed with zinc-plated the manufacturer. „ „ „ „ „ 1

1 9.29.5 „ „ „ „ „ „ „ „ „ „ „ When plastering: The plastermixshouldbe: To avoidsurfacecracking;metallathingorwirenettingshouldbeusedwherethereisaninsufficientdepthofplaster. Table 4: Dry liningshould: Installation b) a) account include: Dry liningshallprovideanadequatesubstratefor thedecorativefinish.Issuestobetakeninto 9.2.4 Drylining Table 3: Where servicesaretobeconcealedbyplaster, theyshouldbe: BS 8212 BS EN520 Ceilings Walls „ „ „ „ „ „ „ „ „ „ „ possible aftercompletion be programmedsothatfinishes areappliedassoon substantially weatherproofed not bestarteduntilthebuildingis prolonged mixing ensure plasteristhoroughlymixedbutavoid of theplaster harmful tothebondorintendedfinishedappearance loose materialorsubstanceslikelytoprove surfaces shouldbedry, cleanandfreefromlaitance,grease, application ofthefirstcoat dubbing outshouldbeconductedwellinadvanceofthe should beremovedandreplaced) 3.2 ‘Coldweatherworking’ (plasterworkdamagedbyfrost in coldweather, followtheguidanceinchapter should beprotectedfromdampanddamage completed work,especiallytimber, chipboardandglazing, an appropriatequalityfortheintendedfinish the background appropriate forthestrengthandsurfacecharacteristicsof manufacturer fortheparticularlocationanduse as specified,orrecommendedbytheplaster completed andtestedbeforeplastering vapour control installation Standards relevanttodrylining Plaster thickness Surface tobeplastered Plasterboard Concrete Plasterboard orconcrete Blockwork Brickwork Metal lathing ‘Code ofpracticefordrylining andpartitioningusinggypsumplasterboard’. ‘Gypsum plasterboards.Definitions, requirementsandtestmethods’.

Minimum numberofcoats 1 2 1 2 2 3

„ „ „ „ „ „ „ „ „ „ „ d) c) „ „ „ „ „ „ „ „ „ „ „ Chapter 9.1‘A consistentapproachtofinishes’ external angles,etc.shouldbeinaccordancewith finished surfaces,reveals,soffitstoopenings, reasonably planefinish the numberofcoatsshouldbesufficienttoachievea to develop) should beleftbetweencoatstoallowstrengthandsuction (the surfaceshouldnotbeoverworked,andadequatetime the backgroundsurfaceofeachcoatshouldbefullyset not beretempered) avoid mixingexcessivequantitiesofplaster(plastershould plaster inthesamemix. of atypethatdoesnotincludePortlandcementandgypsum plastic compoundfinishesareused) applied bysuitablytrainedoperatives(specificallywhere are compatible checked toensureundercoatsandfinishingcoats thermal movement. protected againsttheadverseeffects ofchemicalactionor prevent draughts. ensure thatgapsealingisspecified wherenecessaryto where itcontributestofireresistance provide performanceinaccordancewithbuildingregulations excluding dubbingout,inaccordancewith Table 3. the plastershouldbeappliedtoathickness, fixing. detailing andsupport Wall andceiling finishes Thickness ofplaster Skimcoat 10mm maximum crack-free surface Sufficient toprovidea 13mm maximum 13mm maximum 13mm (nominalfromlathing) CHAPTER 9.2

2020

2 2 9.29.5 t soil pipe or ventilation pipe

pipes insulated when above loft insulation d l seperating membrane between resilien insulation and screed m screed reinforced as specified in the design information 900mm min. less than 3000m rising main insulate above ceiling leve n n e r openings lap the tank insulatio and the loft insulatio perimete membran turned up at perimeter n

e g ground vapour control layer to prevent condensatio damagin wooden flooring dry, bearing slab DPM timber framing either line the enclosure or wrap the pipe with 25mm unfaced mineral fibr the material of the enclosure should have a mass of 15 kg/m³ ventilated void to suspended floor any distance preservative treated battens min. 750mm

h insulated water pipes n min. 25mm cover insulated pipe within screed floor finis insulatio pre cast floor ventilated void ) r vapour control layer (under wood based floors cold ai h n floor finis insulatio DPM ground bearing slab insulation thickness duct sloping to the outside

r s condensation trap lines of noggings at board edges of second laye ’s recommendations, ’s min. 300mm spacing perimeter nogging Yes* Yes Yes Yes Yes Yes Perimeter noggings required Perimeter noggings second layer . d d depth of top shelf floor level min. 0.5mm² pipe to drain condensate to eaves 1500mm max above finished airing cupboar first layer cut board using full width an total area of shelving masonry using adhesive dabs. 6mm minimum from edges of timber members. ceiling boards should be staggered to minimise any risk ceiling boards should be staggered to minimise finished to an appropriate standard and in accordance with consistent approach to finishes’. Chapter 9.1 ‘A Chapter 7.2 ‘Pitched roofs’. Chapter 7.2 ‘Pitched should be openings for services and electrical outlets should be accurately cut (gaps in vapour control layers taped and sealed) of cracking. „ „ „ „ „ „

„ „ „ „ „ „ No No No Yes No Yes Intermediate noggings required Intermediate noggings

2020

600 400 450 600 400 450 Maximum timber support Maximum timber support centres (mm) Frequency of support for plasterboard Frequency of support 9.2 CHAPTER Wall and ceiling finishes ceiling and Wall

10mm minimum from paper-bound edges 13mm minimum from cut ends of boards timber using plasterboard nails or dry wall screws metal using dry wall screws, or completely taped and filled at board joints and at the abutments to ceilings and internal walls be plastered edges supported have the second layer supported on all edges with noggings provided to suit. be positioned so joints are staggered between layers have the first layer fully fixed and have all cut as recommended by the manufacturer. with tape, and filled, where boards are not to be plastered with tape, and filled, where boards are directly applied (tapered edge boards should be used for finishes), or (though are permitted, where necessary, at perimeters) (though are permitted, where necessary, socket outlets and other service installations are to with scrim tape or paper tape, where boards there should be adequate support for light points, there should be adequate support for light they should be fixed face side out, appropriate for plastering they should be fixed face side out, appropriate or directly applied finishes or nogging cut edges should finish over a support damaged boards should not be used Chapter 6.2 ‘External timber framed walls’ timber framed walls’ Chapter 6.2 ‘External and balconies’ Chapter 7.1 ‘Flat roofs „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ 15 12.5 9.5 Board thickness (mm) Fixing Plasterboard should be fixed to: When fixing boards: * unless floor joist manufacturer’s or plasterboard manufacturer’snoggings are required. guidance state that no perimeter Support should be provided to plasterboard in accordance with Table 5. Table with to plasterboard in accordance Support should be provided 5: Table Detailing and support Vapour control control Vapour with: be installed in accordance condensation, and risk of interstitial be used to reduce the layers should control Vapour Where double layers of plasterboard are used, they should: Dry lining should be: Where insulated dry lining is used, nailable plugs should be specified in accordance with the manufacturer Where insulated dry lining is used, nailable plugs should be specified in accordance and at a minimum of two per board. Nails or screws should not project above the board surface and should be: Joints between boards should be neatly formed, flush, and suitably finished: Joints between boards should be neatly „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ 3

3 9.29.5 „ „ Adhesive dabsshouldbeat300mmcentresmeasuredvertically, andinaccordancewith Table 8. Where dryliningisfixedwithadhesivedabs,itshouldbe: Table 8: Table 6: Table 9: Table 7: Dry liningtoreceiveceramicwalltilingshouldbesupportedinaccordancewith Description Thickness ofwallboard(mm) 15 12.5 9.5 Board thickness(mm) Screw Nail Fixing (including studwalling) Timber frame 9.5 Timber battens 9.5 Direct bond 12.5 60mm stud lining,48mmor Independent steel partitions 146mm metalstud partitions 70mm metalstud partitions 48mm metalstud „ „ service points,electricsockets,lightswitches,etc. filled withjointingcompoundwhererequired,atgapsaround including doorandwindowopenings securely fixedandfilledatexternalinternalcorners, Walls: approximately300mmcentres(fiveperlinearmetre) (eight pertwolinearmetres) Ceilings: approximately230mmcentres (eight perlinearmetre) Walls andceilings:approximately150mmcentres Location andspacing Board fixingguidanceforwallstoreceiveceramictiles Dabs accordingtoboarddimensions Acceptable fixinglengths Acceptable fixingcentresandfixings

(mm) Board thickness 12.5, 15 12.5, 15 9.5 2 x12.5 2 x15eachside or 2x15eachside 2 x12.5eachside, 15 or 2x15eachside 2 x12.5eachside, 15 40 40 30 Nail length(mm) Width ofwallboard(mm) 900 1200 1200 (mm) Support centres 600 400-450 400 adhesive inrows 450 dabsof 400 600 400 400 400 400

36 36 32 Screw length(mm)intotimber „ Additional support centres (measuredvertically) Timber noggings 600mm No exceeding 1200mmcentres intermediate positionsnot Battens athead,baseand mid-storey height Horizontal dabsat Mid-point support to tileheight Additional studat300mmup „ services, topreventairinfiltration. perimeter ofexternalwalls,andaroundopenings installed withacontinuousribbonofadhesivetothe Wall andceiling finishes (or to the board manufacturer’s recommendations) (or totheboardmanufacturer’s Zinc electroplatedorblackphosphate steel Hot dipgalvanised,zincelectroplatedorsheradised Coating Table 9ortheguidancegiveninBS8212.

Dabs perboard(rows) 3 4 3 CHAPTER 9.2 25 22 22 Screw length(mm)intosteel height (mm) Maximum 3 600 3 600 3 600 3 600 3 000 3 600 3 600 3 600 3 600 2 700 Comments before tiling least 10days Complete at

2020 4 4 9.29.5

proprietary water-resistant grouting should be used in accordance with the manufacturer’s recommendations. located at junctions where there are variations in surfaces or backgrounds 1-2mm where tiles are without spacer lugs. waterproof in and around shower enclosures and where tiling can be saturated. for thin bed adhesives or 6mm for thick bed adhesives, for thin bed adhesives or 6mm for thick when using a 2m straight edge). very smooth and applying a bonding agent (particularly on dense surfaces). edge shape fittings (coves, skirtings, etc.) hooks, etc.). paper holder, accessories (soap tray, fixed according to the background, using cement mortar or proprietary adhesive solidly bedded in water-resistant adhesive on a moisture-resistant background, where frequent wetting occurs. spacing should be sufficient to allow for expansion up to sanitary fittings and fixings, the sealing method should be in accordance with the design and account for movement surfaces which will become regularly wetted should be tiled regularly wetted should be tiled surfaces which will become alternative water-resistant finish. or have an appropriate movement; where this avoid differential be rigid and stable to should be taken, e.g. metal lathing precautions may occur, across junctions or wire netting fixed where designed for wetting to occur be moisture resistant, grease, loose material clean and free from laitance, be dry, the bond or finish or any substance likely to affect greater than 3mm be reasonably even (i.e. not have gaps repeated or persistent wetting may occur. „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „

2

2020

‘Ceramic tiles. Definition, classification, characteristics, assessment and verification of constancy of ‘Ceramic tiles. Definition, classification, characteristics, assessment and verification performance and marking’. ‘Adhesives for ceramic tiles’. classification and designation’. ‘Grouts for tiles. Requirements, evaluation of conformity, Standards for tiling 9.2 CHAPTER Wall and ceiling finishes ceiling and Wall

as specified in the design, including mix and colour cement-based epoxy resin or a proprietary product vertically and horizontally provided at vertical corners in large tiled areas joints should be even and cut neatly built into tiling at centres at a maximum of 4.5m, there should be no cut or unfinished tiles at exposed edges or external corners courses should be straight and even to form a plane and regular surface, especially around fittings and fixtures fixed in accordance with manufacturers’ instructions fixed in accordance with manufacturers’ suitable for the location, intended use and background; their weight on lightweight plaster should not exceed 20kg/m colour surface finish size and thickness raking out masonry joints hacking and scratching repeated or persistent heating occurs, e.g. on flues or near repeated or persistent heating occurs, e.g. heat sources well bonded) tiled surface suction provide adequate and reasonably consistent provide an adequate mechanical key and plane be sufficiently even to achieve an even be in accordance with Table 9 and BS 8212 9 and BS Table be in accordance with support the weight of the adhesive and be strong enough to coats are used, they should be tiling (where separate a screen or other suitable means of containing the water a screen or other suitable should be provided „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ BS EN 14411 BS EN 12004 BS EN 13888 10: Table Where a fixed shower or showerhead fixing is provided over a bath, at a height that will permit persons to stand under it: a bath, at a height that will permit persons or showerhead fixing is provided over Where a fixed shower Ceramic wall tiling wall Ceramic 9.2.5 appearance use (including location and intended adequate for its provide a surface wall tiling shall Ceramic and durability). When tiling: Appropriately designed movement joints should be: Grouting should be: Where the backing surface contains soluble salts, and where cement mortar is used as an adhesive, precautions should be taken, salts, and where cement mortar is used as an adhesive, precautions should Where the backing surface contains soluble cement. such as the use of mortar with sulfate-resisting Gypsum plasters should not be used where: consideration should be given to: should be appropriate for their location and intended use. When specifying tiles, Tiles should be: Tiles Backing surfaces for tiling should: Backing surfaces for Backgrounds may be improved by: „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ 5

5 9.29.5 Floor finishes CHAPTER 9.3

This chapter gives guidance on meeting the Technical Requirements for floor finishes, including: „„integral insulation „„screeds „„ceramic, concrete and similar tiles „„flexible sheet and tiles „„woodblock „„asphalt.

9.3.1 Compliance 01 9.3.2 Provision of information 01 9.3.3 Insulation 01 9.3.4 Screed 01 9.3.5 Ceramic, concrete, terrazzo and similar tile finishes 03 9.3.6 Wood finishes 04 9.3.7 Flexible sheet and tile finishes 05 9.3.8 Asphalt finishes 06 9.3.9 Staircase finishes 06

Also see: Chapters 3.2 and 8.1 Grade or description 70 For use under screeds Insulating board (softboard) Also see: Chapters 2.1, 5.1, 5.2, 6.4 and 8.1 Chapters 2.1, 5.1, 5.2, Also see: fect the finished construction, and: screed over insulation. in cold weather, screeds should not be installed in cold weather, (screed damaged by cold should be removed and replaced). proprietary products which have been assessed in proprietary products which have been assessed Requirement R3. Technical accordance with suitably prepared to provide an adequate mechanical key, where bonded screeds are required, cement grouting or a bonding agent should be specified to provide adequate adhesion. Extent and detail of tiled surfaces. Extent and detail of Location of services adjacent to tiled surfaces. Details of staircase finishes. „ „ „ „ „ „ c) „ „ „ „ „ „

BS EN 13163 BS 4841 BS EN 622 Requirement R3 Technical Standard

2020

Thermal insulation materials Screed Insulation Provision of information of Provision Compliance CHAPTER 9.3 Floor finishes Floor

installation screed thickness in hot or dry weather, precautions should be taken to prevent in hot or dry weather, the screed surface drying out too quickly should be scheduled to allow suitable drying time before following trades clean and free of debris (e.g. dust and gypsum removed); concrete should be wetted and brushed mineral fibre quilt insulation impact sound board material for use under screeds (e.g. polystyrene) duty (ISD) grade pre compressed expanded flexible material Details of sound insulating floors. Schedule of finishes. Schedule of finishes. Screed thickness and mix. „ „ „ „ „ „ „ „ „ EPS (expanded polystyrene) PUR (rigid polyurethane) PIR (rigid polyisocyanurate) Fibre building board Proprietary material Material Installation Before screeding, background surfaces should be: a) b) 9.3.4 intended use, and provide a suitable Non-structural floor screeds shall be adequate for the location and background for floor finishes. Issues to be taken into account include: Table 1: Table Thermal and acoustic insulation shall provide appropriate performance, and be suitable for the intended shall provide appropriate performance, and be suitable for the intended Thermal and acoustic insulation location and use. accordance with building regulations are generally acceptable. Materials and constructions which are in Suitable sound insulation materials include: 9.3.3 9.3.3 Designs and specifications should be issued to site supervisors, relevant specialist subcontractors and suppliers, and include the relevant specialist subcontractors should be issued to site supervisors, Designs and specifications following information: 9.3.2 include all relevant a clearly understandable format, shall be produced in Designs and specifications personnel. be distributed to the appropriate information and Floor finishes which comply with the guidance in this chapter will generally be acceptable (structural floors should be in will generally be acceptable (structural comply with the guidance in this chapter Floor finishes which relevant Standards chapter). accordance with the 9.3.1 Requirements. Technical with the shall comply Floor finishes Damp proofing should be completed before screeding starts. Screeding should not take place in weather conditions which could adversely af „ „ „ „ „ „ „ „ „ 1

1 9.39.5 „ „ „ „ „ „ „ „ Where servicesarebeddedinthescreed: Surface sealersorhardenersshouldonlybeusedinaccordancewiththemanufacturer Proprietary non-structuralscreedsshouldbeinstalledinaccordancewiththemanufacturer building regulations. Sound insulating floatingfloorsshouldbein accordancewith For concreteground-bearingfloors,amaximum20mmmonolithic screedmaybeacceptableaspartoftherequiredthickness. should bereinforced,andtheinsulationshould: Where screedistobeinstalledoverinsulation,the Standards relevanttoscreedinginclude: Completed floorfinishesshouldbeprotectedagainstdamagefromtraffic. with BS8204-2andpowerfloated. Where concretefloorslabsaretoservedirectlyasawearingsurfacewithoutanadditionaltopping,theyshouldbein accordance Non-structural screedshouldbe: Table 2: Thickness ofcementandsandscreedsshouldbeinaccordancewith Non-structural screedthickness Screed overinsulation Non-structural screedoverunderfloorheatingshould: Above services,reinforcementorinsulationtoservices Installed onresilientslabsorquilts(screedreinforcedwithwiremesh) Installed onaseparatingmembrane(e.g.1000gpolyethylene) Installed on,andbondedto,asethardenedbase Installed monolithicallywithbase Method oflaying BS 8203 BS 8201 BS 8204 „ „ „ „ „ „ „ „ perimeter). have jointslappedandtaped, andbeturnedupatthe membrane shouldbecompatible withtheinsulation,and be separatedfromthescreed byamembrane(the perimeters topreventcoldbridging be tightlybuttedand,whererequired,turnedupat construction screedsandfloorloads provide adequatecompressivestrengthtosupportwet maximum lengthof8m,orinstalledperroom be sub-dividedintobaysnotexceeding40m2,witha water pipes provision shouldbemadeforthethermalmovementof point ofpipesandinsulation there shouldbeaminimum25mmofcoveroverthehighest may beused 1:4½ cement:sand).Wheredeeperthan40mm,concrete of asuitablesandcementmix(generallybetween1:3and recommendations manufacturer’s the relevantBritishStandardsandfloorfinish surface, suitablefortheintendedfinishinaccordancewith installed tothespecifiedthicknessandprovideaneven Thickness ofnon-structuralscreed ‘Code ofpracticeforinstallationresilientfloorcoverings’. ‘Code ofpracticeforinstallationflooringwoodandwood-basedpanels’. ‘Screeds, basesandin-situfloorings.Codeofpractice’.

„ „ „ „ „

„ „ „ „ „ the slab. have expansionjointswhichareconsistentwiththosein (e.g. byusingpurpose-madesleevesorducts). pipes shouldbeprotectedagainstchemicalattack either aheavytamper, mechanicalcompactororvibrator. thoroughly compacted,whererequiredbythedesign,using assessed inaccordancewith Technical RequirementR3 mixed usingonlyproprietaryadditivesthathavebeen within threehoursoftheconcretesub-floorbeingpoured. (where theflooristoincludeamonolithicslab)installed at perimeter turned up membrane perimeter Table 2. 25 65 50 20 12 Minimum thicknessatanypoint(mm) ’s instructions. Floor finishes ’s recommendations. 9.3 CHAPTER the design as specifiedin screed reinforced insulation andscreed between resilien separating membrane

2020 t

2 2 9.39.5

the manufacturer’s recommendations minimum 10mm chipboard floor decking overlaid with acclimatised, plywood suitable for exterior conditions, used to separate bays at 8-10m centres a minimum of 3mm wide unless otherwise specified by water resistant, where tiles may become saturated. differences in level should be dubbed out in level should differences clean and free from laitance, dirt, dust, the surface should be incompatible with the adhesive. grease and materials covings and skirtings, should match accessories, such as are aligned with the tile pattern, and be fixed so that joints those in the floor joints, unless they should be installed with minimum 3mm otherwise specified by the manufacturer. (flexible) they should be bedded with deformable accordance with tile adhesive, e.g. C2S1, and grouted in or proprietary sealed and fixed as previously indicated, boards or tile separating/decoupling layers, tile backer with the bedding reinforcement sheets used in accordance manufacturer’s recommendations. the manufacturer. „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „

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‘Screeds, bases and in-situ floorings. Polymer modified cementitious levelling screeds and wearing screeds. ‘Screeds, bases and in-situ floorings. Polymer modified cementitious levelling Code of practice’. tiles for internal use’. ‘Terrazzo of constancy of ‘Ceramic tiles. Definition, classification, characteristics, assessment and verification performance and marking’. and floor tiling’. ‘Wall CHAPTER 9.3 Floor finishes Floor

cement-based epoxy resin or a proprietary product provided around the floor perimeter and at rigid upstands, where tiled areas are wider than 2m plywood for use in exterior conditions (minimum 15mm for plywood for use in exterior conditions (minimum at joists for 18mm minimum and centres 400/450mm at joists 300mm centres with 600mm centres) screwed to the joists at noggings (plywood all square edges supported on joists or gap between should be installed with a 1.5-2mm movement to the room boards and at abutments, and be acclimatised and square edges, conditions and sealed on the underside as polyurethane before laying, with a suitable sealer such varnish) or the floor should be designed to take the additional loads of the floor should be designed to take the tiles, and any other materials (e.g. overlays) timber base they should be suitable for laying over a the manufacturer’s should be followed recommendations where proprietary adhesives are used and to provide they should be arranged to minimise cutting width joints which are straight, neat, and of even they should be bedded on a solid bed of mortar or they should be bedded for the proprietary adhesive, of a thickness appropriate material ensure the substrate is reasonably true and flat ensure the substrate ensure that the substrate is sufficiently dry (generally, six is sufficiently dry (generally, ensure that the substrate bases and three weeks for screed is weeks for concrete adequate) edge), and installed to falls (±3mm using a 3m straight where required „ „ „ „ „ „ „ „ „ „ BS 8204-3 BS EN 13748-1 BS EN 14411 BS 5385 Before tiling is started: Ceramic, concrete, terrazzo and similar tile finishes and similar terrazzo concrete, Ceramic, 9.3.5 use. location and intended surface for the a suitable wearing shall provide flooring Tile When installing tiles to floors: When installing tiles floor decking should be: Timber Standards relevant to floor finishes include: Where tiles are to be fixed to a wood-based substrate: Where tiles are to be fixed to a wood-based Movement joints should be: Grout should be: „ „ „ „ „ „ „ „ „ „ 3

3 9.39.5 „ „ „ „ „ „ „ „ Wood andwood-basedflooringshouldbeinstalledensuringthat: Screeds orconcretetoreceive woodflooringshouldbedry. Thefloorshould: Condition ofthesubstrate permanently inposition. Where afloorreliesonsoftcoveringtoprovidethe minimumstandardofsoundinsulation,thecoveringshouldbefixed resilient layer. Where flooringistobeinstalledonaresilientmaterial a separatingfloor Floating floorfinishesshouldbedesignedandconstructed to: Sound insulation Proprietary insulatedflooringshouldbeinaccordancewith: Standards relevanttowoodfloorfinishesinclude: c) b) a) Issues tobetakenintoaccountinclude: Wood andwood-basedflooringshallprovideasuitablewearingsurfaceforthelocationintendeduse. 9.3.6 Wood finishes Methods ofprovidinginsulationinclude: Thermal insulationandDPMs BS 1297 BS 1202 BS 4050 BS 1187 BS 8201 „ „ „ „ „ „ „ „ slabs), or two monthsfor 50mmscreed,andsixmonths forconcrete be allowedtocureforasufficient periodoftime(generally with BS8201 be testedandthemoisturecontent suitable,inaccordance avoid excessivemovementorsqueaking isolate thefloorfinishfromsupportingandwalls Technical RequirementR3 (DPM required) insulation positionedabovein-situconcreteslab floor laying underfloor heatingiskepton,beforeandduringthe is installed services beneaththefloorfinisharetestedbefore condition ofthesubstrate sound insulation thermal insulationandDPMs ‘Specification fortonguedandgrooved’. ‘Specification fornails’. ‘Specification formosaicparquetpanels’. ‘Specification forwoodblocksfloors’. ‘Code ofpracticeforinstallationflooringwoodandwood-basedpanels’. ground-bearing slab DPM insulation floor finis h

Also see:BS5250andBREReport‘Thermalinsulation:avoidingrisks’

„ „ „ „ „ „ „ e) d) „ „ „ „ „ „ „ manufacturer’s recommendationsandthedesign. manufacturer’s where required,DPMsareincorporated,inaccordancewith moisture content wood finishesareconditionedtotheappropriate not betrappedbetweenthelayers). construction toprotectthewood finishes(moistureshould have aDPMorvapourcontrol layerincorporatedinthefloor ensure therearenoairpaths,especiallyattheperimeter. avoid theuseoffixingswhichpenetrateinsulationlayer and DPMs. recommendationsonvapourcontrollayers manufacturer’s (DPM notrequired). insulation positionedabovedry, precastsystem indirectly appliedfinishes. directly appliedfinishes , edgesshouldbeisolatedfromwallsandskirtingsbya (under wood-basedfloors) vapour controllayer

Floor finishes 9.3 CHAPTER

ventilated void precast floor insulation floor finis

h 2020

4 4 9.39.5

‘Thermal insulation: avoiding risks’ Also see: BS 5250 and BRE Report Maximum batten centres (mm) 450 600 450 600 450 600 at 200mm-300mm centres at perimeters at 400mm centres on intermediate supports. at 150mm centres at perimeters at 300mm centres on intermediate supports. reasonably level and smooth, particularly at doorways and junctions fitted with skirtings, coves, coverstrips and other preformed components, where required, and in accordance with the manufacturer’s recommendations. have differences in level dubbed out. in level dubbed have differences adhesives using evenly spread pattern, and leaving gaps around according to the specified the perimeter for movement. battens fixed to prevent excessive movement 3. Table battens spaced in accordance with „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ Minimum thickness (mm) 3.2 4 9 6 Thickness of finish (mm) 18/19 22 18 18/19 15 15 In accordance with the manufacturer’s instructions.

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Acceptable types of underlay for boarded surfaces Spacing of battens for indirectly applied floor finishes Spacing of battens for indirectly applied Flexible sheet and tile finishes sheet Flexible CHAPTER 9.3 Floor finishes Floor

installed on a backing surface which is even and without using a levelling high spots or cracks; where necessary, underlay of a type and thickness recommended by the Table 4 flooring manufacturer or in accordance with installed in accordance with the manufacturer’s recommendations, and generally be fully bonded with 10 gauge nails or screws a minimum of 10mm from the edges of boards with fixings 2.5 x the thickness of the board with flathead ring shank nails or screws provision made to support heavy items, such as storage provision made to support heavy items, heaters and boilers vapour control layers where required with Chapter 3.3 preservative treated battens, in accordance preservation (natural solid timber)’ ‘Timber in accordance with the manufacturer’sin accordance with the recommendations in e.g. bitumen rubber emulsion using the correct adhesives, 8201 or proprietary adhesives assessed accordance with BS R3 Requirement Technical in accordance with be free from high spots, nibs and major irregularities and major irregularities high spots, nibs be free from „ „ „ „ „ „ „ „ „ „ „ „ Chipboard (type P5) Plywood Oriented strand board (type OSB3) Other types of floor Type of underlay Type Hardboard Plywood Chipboard Oriented strand board Chipboard and oriented strand board should be fixed to battens: Chipboard and oriented strand board should Table 4: Table Flexible sheet and tile finishes should be: 9.3.7 for the location and intended use. Flexible sheet and tile finishes shall provide a suitable wearing surface Table 3: Table Indirectly applied finishes (softwood boarding, wood-based panel products) wood-based panel products) finishes (softwood boarding, Indirectly applied with: Indirectly applied finishes should be installed Screeds or concrete surfaces should be treated with a suitable primer in accordance with the adhesive primer in accordance with the adhesive surfaces should be treated with a suitable Screeds or concrete manufacturer’s recommendations. Directly applied finishes (wood blocks, parquet, wood mosaic, etc.) finishes (wood blocks, parquet, Directly applied should be installed: Directly applied finishes Screeds or concrete to receive wood flooring should: concrete to receive Screeds or Plywood should be fixed to battens: „ „ „ „ „ „ „ „ „ „ „ „ 5

5 9.39.5 „ „ „ „ „ „ „ „ „ „ „ „ „ „ When installingflexiblesheetortileflooring: The substrateshouldbesufficientlydrytopreventadverseeffects ontheflooring,andwhere: Flexible sheetflooringmaterialsshould: Plywood orhardboardunderlayshouldbefixed: For communalstairs(e.g.inescaperoutesblocksofflats), non-slipnosingsorinsertsshouldbe: The riseandgoingshouldremainuniformafterapplication ofthestaircasefinish,includingattopandbottomflight. Staircase finishesshallpermitsafeusageandbe suitablefortheirintendeduse. 9.3.9 Standards relevanttoflexiblesheetandtilefinishesinclude: Chipboard andorientedstrandboardunderlayshouldbefixedtobattens: Asphalt finishesshallbesuitableforthelocationandintendeduse. 9.3.8 Asphaltfinishes Asphalt shouldbe: BS ENISO10595 BS ENISO10581 BS 8203 BS EN12104 BS EN651 BS EN650 „ „ „ „ „ „ „ „ „ „ „ „ „ „ provided wherespecified finishes andunderlay) Grade IorIIand15-20mmthick(whichappliestothefloor in accordancewithBS6925(limestoneaggregate) as necessarytopreventcurling,liftingorbubbling the surfaceshouldbepresseddownfirmly, loadedorrolled period oftimetoensurefullbonding adhesives shouldbespreadevenlyandleftforthecorrect it should be cut so that it fits neatly around fittings, pipes, etc. ensure underfloorservicesarenotdamaged condensation, permeablefinishesshouldbeused there isariskoftrappingmoistureorinterstitial the manufacturer not bestoredincoldconditions,unlesspermittedby be storedinacleanandventilatedplace with nails/screwsatleast10mmfromtheedgeofpanel with ringshanknailsorstaples with fixings2.5xthethicknessofboard with flatheadringshanknailsorscrews Staircase finishes ‘Resilient floorcoverings.Semi-flexible/vinylcomposition(VCT)poly(vinylchloride)tiles’ ‘Resilient floorcoverings.Homogeneouspoly(vinylchloride)covering’ ‘Code ofpracticeforinstallationresilientfloorcoverings’. ‘Resilient floorcoverings.Corktiles’ ‘Resilient floorcoverings.Polyvinylchloridecoveringswithfoamlayer on apolyesterfeltwithpolyvinylchloridebacking’ ‘Resilient floorcoverings.Polyvinylchloridecoveringsonjutebackingorpolyesterfelt

„ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ made wherenecessary. adjustment afterinitialcontractionorexpansionshouldbe recommendations manufacturer’s welded jointsshouldbeprovidedinaccordancewiththe surplus adhesiveshouldberemoved rising moistureadverselyaffecting floorfinishes. concrete floors,aDPMshouldbeincorporatedtoprevent flexible sheetortileflooringisinstalledongroundbearing of 24hoursbefore,orduring,laying. not beexposedtotemperatureslessthan18°Cforaperiod across thesheets,at150mmcentres. around perimeters,at100mmcentres(12mmfromedges) across theboards,at400mmcentres. at 200mm-300mmcentres(9mmfromedges) manufacturer’s recommendations. manufacturer’s fixed inaccordancewiththe system. recommendations whenusedwithasuspendedfloor in accordancewiththefloormanufacturer’s applied asonecoatwhenusedunderlayforotherfinishes Floor finishes 9.3 CHAPTER

’ Also see:Chapter6.6

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6 6 9.39.5 Finishings and fitments CHAPTER 9.4

This chapter gives guidance on meeting the Technical Requirements for finishings and fitments (including cupboards and internal trim).

9.4.1 Compliance 01 9.4.2 Provision of information 01 9.4.3 General provisions – cupboards and fitments 01 9.4.4 Finishings and internal trim 01 9.4.5 Joinery 02 9.4.6 Airing cupboards, cupboards, worktops and fitments 02 9.4.7 Ironmongery, prefabricated items and other materials 02 9.4.8 Protection and handover 03

Also see: Chapter 2.1 Also see: Also see: Chapter 6.8

’s recommendations. ’s Airing cupboards are required in homes which do not Airing cupboards are required in homes ’s instructions, ensuring that they are adequately fixed to a instructions, ’s fixed with an equal margin to each frame member securely fixed to prevent curling. tightly abut architraves run level and scribed to floors. nails should be punched below the surface of timber, nails should be punched below the surface of timber, and holes filled damage should be avoided (where damage does occur, it should be made good). selected and installed to give a neat appearance installed in accordance with the manufacturer’s recommendations. storage of domestic cleaning appliances (part of which storage of domestic cleaning appliances and should be suitable for brooms, upright cleaners similar equipment) surfaces, 1m circulation space in front of all work cupboards and appliances. „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „

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Finishings and internal trim Finishings and internal Provision of information of Provision General provisions – cupboards and fitments – cupboards provisions General Compliance CHAPTER 9.4 Finishings and fitments and Finishings

etc. allowing for movement and shrinkage as appropriate be mitred and scribed at external and internal angles, parallel to frames and linings accurately mitred, or scribed, to fit tightly and neatly fixed in accordance with building regulations (e.g. with minimum separation distances where near heat sources) sufficiently wide to mask joints around built in fitments, fireplace surrounds, panelling and features should be complete and suitably joined to the adjacent surfaces they should be in accordance with the specification storage of dry foods storage of perishable foods laundering preparation and cooking of food and utensils washing up, drying and storage of dishes „ „ „ „ „ „ „ „ „ „ „ „ have central or whole home heating. with the manufacturer Kitchen units should be installed in accordance suitable substrate. and so that shelves are level. Shelving supports should be fixed securely When fixing trim and components: 9.4.4 9.4.4 finished be suitable for their location and intended use, securely fixed, and Finishings and internal trim shall to established standards of workmanship. A depth of 600mm can be assumed for appliances (where intended but not provided). depth of 600mm can be assumed for appliances A items may be provided outside the kitchen area. Space or facilities for laundering and cleaning clothes, linen and bedding. Space should be provided for general storage, The builder shall provide fixed and built-in fitments in accordance with the specification. provide fixed and built-in fitments The builder shall for: In kitchens, the specification should allow Designs and specifications should be issued to site supervisors, relevant specialist subcontractors and suppliers. relevant specialist subcontractors should be issued to site supervisors, Designs and specifications 9.4.3 Designs and specifications shall be produced in a clearly understandable format, include all relevant a clearly understandable format, shall be produced in Designs and specifications personnel. be distributed to the appropriate information and Finishings and fitments which comply with the guidance in this chapter will generally be acceptable. this chapter will generally be acceptable. which comply with the guidance in Finishings and fitments 9.4.2 9.4.1 Requirements. Technical the shall comply with and fitments Finishings Skirting should: manufacturer Proprietary trim, skirting and architraves should be fixed in accordance with the Trim and finishings should be: Trim Architraves should be: „ „ „ „ „ „ „ „ „ „ „ „ 1

1 9.49.5 „ „ „ „ „ „ „ „ „ „ „ Airing cupboardsshould: Internal doors(includingairingcupboarddoors)shouldbefittedinaccordancewithChapter6.7‘Doors,windowsand glazing’. Wardrobes should befittedwithhangingrails,andintermediatesupportsusedwherenecessarytoavoidbending. Where appropriate,gapsbetweenfitmentsandwalltilingshouldbesealedwithawaterproofjointbroughttosmooth finish. units, shouldbesealedwithawaterproofjoint. adhesive. Alternatively, anappropriatewaterproofjointmaybe used.Sinksandhobunitswhichareinsetinworktops,vanity Where worktopsorunitpanelsarecut,edgesshouldbesealedusingametalplasticstripgluedtotheedgewithwaterproof Cupboards (includingwall-hungunits)shouldbesecurelyfixed,using: Cupboards shouldbeinstalledensuringthat: Relevant standardsinclude: Ironmongery, prefabricated Itemsandothersimilarmaterialsshallbesuitable fortheintendeduse. 9.4.7 Relevant standardsinclude: finish hasbeenapplied.Issuesthatshouldbetakenintoaccountinclude: Joinery andthematerialsusedshouldbeinstalledtoestablishedstandardsofworkmanship,havenovisibledefectsafter Wood andwood-basedmaterialsshallbeofthequalitydimensionsrequiredbydesign. 9.4.5 Cupboards, worktopsandfitmentsshouldbe: and performance.Thebuildershallprovidefixedbuilt-infitmentsinaccordancewiththedesign. Airing cupboards,worktopsandfitmentsshallbeinstalledtoprovidesatisfactoryappearance 9.4.6 Airingcupboards, cupboards, worktops andfitments BS 1186 BS EN312 BS EN942 „ „ „ „ „ „ „ „ „ „ „ Requirements and testmethods’. BS EN1935‘Buildinghardware. Single-axishinges. not haveshelvinghigherthan1.5m. have asuitableheatsource,suchashotwatercylinder have a300mmminimumspacingbetweenshelves have aminimum0.5m be separatedfromotherstorage masonry andscrewstotimber) instructions(generally,manufacturer’s plugsandscrewsto fixings ofanappropriatesize,andinaccordancewiththe doors operatefreelyandfitopeningscloselyevenly are installed checked toensuretheyareundamagedbefore gluing andlaminating fit andconstructionofjoints(includingfingerjoints) for theairingofclothes Ironmongery, prefabricated items andother materials Joinery

‘Timber forandworkmanshipinjoinery’. ‘Particleboards’ ‘Timber injoinery. Generalrequirements’ 2 ofeasilyreachedshelvingsuitable

„ „ „ „ „ „ „ „ „ „ „ „ plumb, levelandscribedtowallfaces,wherenecessary. between unitsmayrequireadditionalsupport) installed asshowninthedesign(worktopsspanning surface finishes. construction ofmovingparts the manufacturer. the predrilledholesinunitsandbracketsprovidedby properly engage. drawers runsmoothly, andlockscatches

Finishings andfitments min. 0.5m total areaofshelving of airingcupboard full widthanddepth floor level above finished 1.5m max. top shelf 2 using

9.4 CHAPTER spacing min. 300mm

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2 2 9.49.5

. temporary coverings and protection should be removed, temporary coverings finishings cleaned and dusted. and the fitments and „ „

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Protection and handover and Protection CHAPTER 9.4 Finishings and fitments and Finishings

chapter 9.5 ‘Painting and decorating’ chapter 9.5 ‘Painting decorating should be completed in accordance with decorating should be work should be left in a clean state work should be left „ „ Appropriate protection should be provided to finishings and fitments (including to doors, trim, balustrades, fireplace surrounds, fitments (including to doors, trim, balustrades, should be provided to finishings and Appropriate protection doors, fittings and worktops, damaged. Kitchens, including cupboards, special features) to ensure they are not panelling and other should be suitably protected. and handover: Prior to completion 9.4.8 at handover and be undamaged construction, protected during shall be suitably and fitments Finishings „ „ 3

3 9.49.5 Painting and decorating CHAPTER 9.5

This chapter provides guidance on meeting the Technical Requirements for painting and decorating.

9.5.1 Compliance 01 9.5.2 Provision of information 01 9.5.3 Storage 01 9.5.4 Conditions for painting and decorating 01 9.5.5 Timber 01 9.5.6 Steel 02 9.5.7 Walls 02 9.5.8 Wallpapering 03 9.5.9 Other surfaces 03 9.5.10 Completed painting and decorating 03 Also see: Chapter 2.1 Also see: ’s recommendations, and be compatible with the ’s where there is deterioration of the primer or seal coat, surfaces are rubbed down and a second coat applied where joinery is delivered preprimed, priming meets the requirements in this chapter where joinery is prefabricated, the first coat of paint or stain is applied before fixing. surfaces are moist rain is expected before the paint dries. before applying surfaces should be free from condensation paint and coatings; they should not be applied until the moisture has evaporated from the surface. surfaces are free from dirt, dust and moisture details of specialist finishes. by frost. not be used where they have been damaged „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „

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Storage 9.5 CHAPTER Painting and decorating and Painting

are cut out, replaced and made good as appropriate nail holes, splits and other imperfections are stopped sharp arrises are rubbed down (to enable an even coating) raised grains, tool and machine marks are removed surfaces are refinished with fillers and glasspaper door and window furniture is removed unsound wood, loose or highly resinous knots, etc. paintwork should not be adversely affected by dust paintwork should not be adversely affected cold surfaces may cause problems with water-borne paints, cold surfaces may cause problems with even though the air temperature may be above freezing weather conditions may adversely affect the completed work the completed weather conditions may adversely affect has been before the paint frost occurs, or is due to occur, applied or has dried be protected against frost before use specification of preparatory work schedule of finishes „ „ „ „ „ „ „ „ „ „ „ „ „ When painting or decorating timber, the moisture content should be a maximum of 18%. the moisture When painting or decorating timber, Paint and paint systems should be used in accordance with the manufacturer Timber 9.5.5 shall be compatible with the species The painting and decorating of timber and timber-based materials use and location. Prefabricated provide adequate protection and be suitable for the intended of timber, and protected. components and joinery shall be finished to a suitable quality, surface to be decorated. Preparation should ensure: Painting and decorating shall take account of the climatic and building conditions to ensure a suitable finish. account of the climatic and building conditions to ensure a suitable Painting and decorating shall take surfaces should not be undertaken where: The painting and decoration of external Conditions for painting and decorating painting for Conditions 9.5.4 Materials for painting and decorating shall be adequately protected from the cold. Materials for painting and decorating Painting and decorating materials should: 9.5.3 Designs and specifications should be issued to site supervisors, relevant specialist subcontractors and suppliers, and include: relevant specialist subcontractors should be issued to site supervisors, Designs and specifications Designs and specifications shall be produced in a clearly understandable format, include all relevant a clearly understandable format, shall be produced in Designs and specifications personnel. be distributed to the appropriate information and Provision of information of Provision 9.5.2 Painting and decorating that complies with the guidance in this chapter will generally be acceptable. that complies with the guidance in Painting and decorating Code of practice’. with BS 6150 ‘Painting of buildings. be selected and applied in accordance Paint finishes should finishes. on the quality of painting and decorating provides further guidance approach to finishes’ consistent Chapter 9.1 ‘A 9.5.1 Compliance 9.5.1 Requirements. the Technical shall comply with and decorating Painting When decorating internal walls: „ „ „ „ „ „ „ „ „ „ „ „ „ 1

1 9.59.5 „ „ „ „ „ „ „ „ „ „ „ „ Prefabricated joineryandcomponentsshouldbe: BS EN927-1providesguidanceonexteriorwoodcoatingsystems. Stain should: the conditions(yachtorhighgloss)andappliedwithaminimumoffourcoats.Surfacesshouldbesandedbetween Varnish shouldbeappliedwithaminimumofthreecoatsoninteriorsurfaces.Onexteriorsurfaces,varnish suitablefor Stain andvarnishesshouldbe: Undercoat andglossshouldbeappliedensuringthatitprovidesasatisfactoryfinish,and: with preservativetreatment. treated (unlessthepreservativetreatmentmanufacturerconfirmsotherwise).Primer Paint orstainshouldbeappliedtoexternaltimberprovideprotectionandstability Primers shouldbeinaccordancewithBS7956‘Specificationforprimerswoodwork’. One fullroundcoatofprimershouldbeappliedtoallsurfacespainted,including: Paint ordecorativefinishesto externalmasonryandrenderingshould: External masonryand rendering a) Issues tobetakenintoaccountinclude: Walls shallbefinished toprovideanevenandconsistentappearance,establishedlevelsofworkmanship. 9.5.7 should befollowed. Any damagetotheprotectivecoatingsshouldbemadegoodpriordecorativefinishesbeingapplied. accordance withChapter6.5‘Steelwork’,mustbecompatible withtheprotectivecoating. Decorative finishesappliedtosteelworkthathasbeenprotected bycoatings(includingintumescentpaintforfireresistance)in Decorative finishesmaybeappliedtogalvanisedsteelfollowing suitablepreparationwithamordantwash. Steelwork shallbecoatedtoprovideadequateprotectionandsuitablefortheintendeduse location. 9.5.6 Steel Knotting should: „ „ „ „ „ „ „ „ „ „ „ „ loose deposits be appliedtosurfaces whichareclean,free from dustand recommendations the manufacturer’s be appropriateforthesubstrate, andbeinaccordancewith supplied with,orgiven,acoatofprimerbeforefixing protected fromdamage recommendations manufacturer’s be atwo-coatsystemorinaccordancewiththe provide adequateadhesionandanacceptableappearance applied tosurfaceswhichhavebeensuitablyprepared appropriate cover applied asrecommendedbythemanufacturertoprovide rubbed downwithglasspaperbetweencoats each applicationisafullroundcoatandsurfacesarelightly it isnotthinned(unlessrecommendedbythemanufacturer) cut endsofexternalwoodwork hidden surfacesofexternalwoodwork not beeffective againstheavyexudationofresin) comply withBS1336‘SpecificationforKnotting’ (thismay external masonryandrendering Walls

„ „ „ „ „ „ „ „ „ „ b) „ „ „ „ „ „ „ „ „ „ suitable forthespeciesoftimber. applied whenthesubstrateisdry each coatisappliedwithinonemonthoftheprevious. recommendation ismadebythemanufacturer) one finishingcoatareused(unlessanalternative a minimumofoneprimingcoat,undercoatand rebates forglazingandbacksofbeads. for joinery. be appliedusingabrush,oraspartoftheprimingprocess damage, sulfate attackorotherdetrimentaleffects. could trapmoistureintheconstruction andcausefrost not beappliedtoexternalbrickwork orrenderwherethey reprimed whereprimerisdamaged. as soonpossibleafterdelivery stored undercoverandprimed,wheresupplieduntreated, glazed withlinseed-oilputty. not beappliedtodoororwindowrebateswhichare plaster andplasterboardsurfaces. Painting anddecorating , evenwherethetimberhasbeenpreservative , paintandstainfinishesshouldbecompatible The manufacturer’s recommendations The manufacturer’s CHAPTER 9.5

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2 2 9.59.5

.

’s recommendations. ’s ’s recommendations and the design. recommendations and the ’s ’s written agreement to the application of a to the application written agreement ’s where ironmongery has been removed, it should be correctly replaced removed and reapplied where spilt, splashed or badly applied protected against dirt and damage until handover. they should be properly aligned and neatly fixed they should be properly aligned and neatly removed and electrical switch plates should be temporarily it will tuck behind the papering accurately trimmed so that the fitting upon completion. appropriate sealants should be used in accordance with the manufacturer’s recommendations. surfaces should be stabilised, either with a coat of thinned surfaces should be by the manufacturer paint or with a sealant as recommended be applied. a minimum of two coats of paint should

„ „ „ „ „ „ „ „ „ „ „ „ „ „ „ „

2020

Other surfaces 9.5 CHAPTER Painting and decorating and Painting

evenly applied, free from conspicuous runs or prominent brush marks, and the background or undercoat should not be visible surfaces that are not intended to be painted should be free of paintmarks linseed-oil putty should not be specified surfaces should be sized or sealed as necessary the wallpaper adhesives should be in accordance with manufacturer’s recommendations surfaces should be dry, even and smooth before wallpaper surfaces should be dry, is applied the surface should be rubbed down with glasspaper the surface should be rubbed down with surfaces should be visibly sound, without signs of powdering visibly sound, without signs of powdering surfaces should be or crumbling nail holes and joints should be completed and cracks, surface imperfections filled and dusted, where necessary „ „ „ „ „ „ „ „ „ Painting and decorating should be complete, and: Completed painting and decorating painting Completed 9.5.10 and suitably protected. Completed paintwork shall be to established levels of workmanship The insides of metal gutters (other than aluminium) should be painted with a suitable protective paint. The insides of metal gutters (other than aluminium) should be painted with a suitable finishes. Non-ferrous pipework (e.g. copper pipes) should be painted with the normal decorative Technical Requirement R3. Requirement Technical the manufacturer with a treatment recommended by varying suction, they should be stabilised Where surfaces have of workmanship. of workmanship. For glazing rebates in windows and doors treated with stains: 9.5.9 an even and consistent appearance, to established levels Surfaces shall be finished to provide Where wallpaper or coverings are used: Wallpapering shall be finished to provide an even and consistent appearance, to established levels finished to provide an even and consistent appearance, to established shall be Wallpapering Where building boards are used, coatings should be in accordance with the board manufacturer Where building boards are used, coatings papering Wall 9.5.8 finish should be obtained. finish should with be assessed in accordance rendering, it should resistance of the is part of the weather decorative system Where the coat is applied to plasterboard: Where plaster and skim Plaster and plasterboard surfaces Plaster and plasterboard manufacturer’s for decoration, in accordance with the to dry lining, and surfaces prepared sealing coat should be applied A recommendations. with the manufacturer surfaces should be prepared in accordance Plaster and plasterboard Where bricks have no upper limit on their soluble salt content, the brick manufacturer salt content, the brick on their soluble have no upper limit Where bricks „ „ „ „ „ „ „ „ „ 3

3 9.59.5 Garages CHAPTER 10.1

This chapter gives guidance on meeting the Technical Requirements for integral, attached and detached garages.

10.1.1 Compliance 01 10.1.2 Provision of information 01 10.1.3 Garage foundations 01 10.1.4 Garage floors 02 10.1.5 Garage walls 03 10.1.6 Resistance to fire spread 03 10.1.7 Security 04 10.1.8 Doors and windows 04 10.1.9 Garage roofs 04 10.1.10 Permanent prefabricated garages and carports 05 10.1.11 Services 05 m

e min. 100m min. 100mm hardcor

Also see: Chapter 2.1 Also see: ferential loads and m min. 300m m ground level min. 350m adjacent structures underground services provision for movement. 4.4 ‘Raft, pile, pier and beam foundations’. 5.1 ‘Substructure and ground-bearing floors’. Construction details of the roof structure and coverings. Construction details for walls. Construction details External and internal finishes. Services, where applicable. „ „ „ „ „ „ d) e) f) „ „ „ „ „ „

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10.1 CHAPTER Garages

hazardous ground garages type of foundation required for integral/attached garages and type of foundation required for detached blocks of garages be provided. be constructed on 100mm minimum of properly compacted hardcore have dimensions not exceeding 6m in any direction – for dimensions greater than this, movement joints should have a minimum downstand thickening of 350mm below ground level around the whole perimeter of the slab have a minimum width of edge thickening of 300mm have a minimum thickness of 100mm 4.1 ‘Land quality – managing ground conditions’. 4.1 ‘Land quality – managing ground conditions’. 4.2 ‘Building near trees’. Waterproofing arrangements. Waterproofing Location of garages. Location of garages. to an agreed reference point. Relevant levels, in relation Details of foundations.

„ „ „ „ „ „ „ „ „ „ „ „ Type of foundation required for detached garages and blocks of garages of foundation required for detached garages and blocks Type damage caused by dif Foundations for detached individual garages or blocks of garages should avoid Type of foundation required for integral/attached garages Type the home, unless proper consideration is given to Foundations for integral or attached garages should be the same as those for movement between them. each foundation, and the possibility of differential Hazardous ground the following chapters are relevant: For foundations on hazardous ground, Garage foundations should adequately support the imposed loads, taking account of ground conditions. Garage foundations should adequately ‘Strip and trench fill foundations’. Further guidance is given in Chapter 4.3 Garage foundations shall transmit all loads to the ground safely and without undue movement. Issues to be all loads to the ground safely and without undue movement. Issues Garage foundations shall transmit taken into account include: a) b) c) Garage foundations Garage 10.1.3 Designs and specifications should be issued to site supervisors, relevant specialist subcontractors and suppliers, relevant specialist subcontractors should be issued to site supervisors, Designs and specifications information: and include the following uneven settlement. eWhere the ground is uniform and provides a satisfactory foundation bearing, an unreinforced edge thickened concrete slab may b used. Unreinforced concrete slabs should: Provision of information of Provision 10.1.2 include all relevant a clearly understandable format, shall be produced in Designs and specifications personnel. be distributed to the appropriate information and Garages which comply with the guidance in this chapter will generally be acceptable. with the guidance in this chapter will Garages which comply 10.1.1 Compliance 10.1.1 Requirements. the Technical shall comply with Garages Any existing fill on the site of the garage should be examined and identified. Where any potential health hazard or risk of damage Any existing fill on the site of the garage should be examined and identified. chapters: is indicated, appropriate precautions should be taken, as described in the following „ „ „ „ „ „ „ „ „ „ „ „ 1

1 10.1 „ „ „ „ „ „ unventilated where: Unless ventilationisspecificallyrequired,thevoidbeneathagaragefloorwhichsuspendedprecastconcretemay be Garage floorswillbeacceptablewheretheyareinaccordancewith: Technical RequirementR5. Where reinforcedscreedsare to by an engineerinaccordance with be incorporatedasstructuraltopping, theyshouldbedesigned Structural topping vehicle doorway. When practicable,garagefloors shouldtobelaidfallsensurethatwaterorspillage isdirectedoutofthegaragevia Floor drainage Ground-bearing floors,whereprovided,shouldnotbeless than100mmthick,includingafloatfinish. Thickness offloorslabs be required. Where thefloorisbelowgroundlevel,precautionsshould be takentopreventtheentryofgroundwater Where noDPMisprovided,thefloormayshowsignsofdampness. Resistance ofthefloortomoisturefromground isolating membraneshouldbeprovidedbetweentheconcreteandground. Where protectionisneededtopreventattackbysulfatesineithertheground,groundwaterorfillbelowslab,animpervious Supporting fillshouldcomplywiththerequirementsinChapter5.1‘Substructureandground-bearingfloors’. and BS8103-1. Where thedepthoffillexceeds600mm,concretefloorsshouldbeinaccordancewithChapter5.2‘Suspendedground floors’ Bearing capacityoftheground c) b) a) undue movement.Issuestobetakenintoaccountinclude: Garage floorsshalltransmitallloadstoeitherthefoundationsorgroundsafelyandwithout 10.1.4 Garage floors Movement jointsinfoundationsshouldbeprovided: Provision formovement damage toservicesoccurs(seeChapter5.3‘Drainagebelowground’). Garage foundationsthataretobeaboveornearservicesshouldconstructedsonoexcessivesettlementof Underground services Foundations forgaragesshouldnotimpairthestabilityofhomeoranyotheradjacentstructure. Adjacent structures Generally, aDPMisunnecessary, except where: „ „ „ „ „ „ it isneededtopreventdampnessenteringthehome,or the groundbeneathiswelldrained the floorhasadequatedurability Chapter 5.2‘Suspendedgroundfloors’ Chapter 5.1‘Substructureandground-bearingfloors’ change offoundationtypeordepth between homesandattachedgarageswherethereisa thickness offloorslabs resistance ofthefloortomoisturefromground bearing capacityoftheground „ „ „ „ e) d) „ „ „ „ the guidancegiveninthischapter. foundations areused. at 6mintervalswhereunreinforcedconcreteslab the ground. the floorhastobeprotectedagainstchemicalattackfrom there isunlikelytobeabuild-upofsoilgases. structural topping. floor drainage CHAPTER 10.1 Garages , andtankingmay

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provision for movement to rain and ground water. adequate resistance where there are movement joints in foundations. the use of DPCs and DPMs drainage of ground behind the wall. constructions where nominal half-hour fire resistance can be proven. the guidance given below. the guidance given have piers at the in the case of walls up to 200mm thick, and at intermediate corners (unless buttressed by a return) centres not exceeding 3m. structurally adequate. „ „ „ „ „ „ „ c) d) „ „ „ „ „ „ „

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10.1 CHAPTER Garages

stability of walls above ground stability of walls above ground stability of walls retaining a half-hour fire-resisting floor or ceiling a wall in brickwork, blockwork or fire-resisting studwork up to the underside of the roof covering tanking (see Chapter 5.4 ‘Waterproofing of basements and tanking (see Chapter 5.4 ‘Waterproofing other below ground structures’) between homes and attached garages suitable for the ground conditions be not less than 90mm thick wind loading have adequate lateral restraint against Chapter 6.1 ‘External masonry walls’ masonry walls’ Chapter 6.1 ‘External Chapter 5.1 ‘Substructure and ground-bearing floors’ and ground-bearing floors’ Chapter 5.1 ‘Substructure „ „ „ „ „ „ „ „ „

Fire resistance between homes and integral or attached garages, may be provided by: Fire resistance between homes and integral or attached garages, may be provided Resistance to fire spread fire to Resistance 10.1.6 home from the garage. Garages shall be constructed so as to prevent fire spread to the ground-bearing floors’ or by an engineer in accordance with Technical Requirement R5. Technical Requirement in accordance with or by an engineer ground-bearing floors’ Adequate resistance to rain and ground water Adequate resistance to rain and at a level at least 150mm above the level of protect the wall from rising ground moisture, a DPC should be provided To Movement joints in garage walls, as described in BS EN 1996-2, should be provided: Movement joints in garage walls, as described Where garage walls act as retaining walls, they should be designed in accordance with Chapter 5.1 ‘Substructure and they should be designed in accordance with Chapter 5.1 ‘Substructure and Where garage walls act as retaining walls, Provision for movement Garage walls retaining ground should be: Stability of walls retaining ground Walls for detached garages and external walls for attached garages should: and external walls for attached garages for detached garages Walls Stability of walls above ground Stability of walls adjacent ground. approximately 100mm thick, will not be such as brickwork or blockwork leaf of masonry, Garage walls constructed from a single could become damp. impervious to wind-driven rain and consequently and possibly surface treatment to In areas of severe exposure, single leaf walls may require a high standard of workmanship prevent an unacceptable level of rain penetration. cannot enter the home. Where a garage is integral or attached, the design should ensure that dampness entry of ground water by: Where a wall is below ground level, precautions should be taken to prevent the a) b) Garage walls Garage 10.1.5 to be movement. Issues and without undue safely all loads to foundations shall transmit for garages Walls include: taken into account Garage walls will be acceptable where they are in accordance with: acceptable where they are in accordance Garage walls will be „ „ „ „ „ „ „ „ „ 3

3 10.1 „ Garage roofswillbeacceptablewheretheyareinaccordance with: should be3.35mm (10gauge)x65mmlong galvanizedroundwirenails. All timberbracing totrussedraftersshouldbe atleast100mmx25mmin section andnailedtwicetoeach trussedrafter roofs’, unlesstheroofisdesigned andbracedinaccordancewithPD6693-1. The buildingdesignershould specify allbracing. Trussed rafterroofsshouldbebracedinaccordancewith Chapter7.2‘Pitched Bracing be atleast1mlongandhave three fixingstothewall. centres wheretheroofmembersbearonsupportingwall. Strapsshouldhaveaminimumcross-sectionof30mmx2.5mm, To preventuplift,flatroofsand,where necessary, pitchedroofsshouldbeprovided withholding-downstrapsatnotmorethan2m Holding down c) b) a) Issues tobetakenintoaccountinclude: applied loadsandself-weight,transmitthetowallssafelywithoutunduemovement. Garage roofsshallsatisfactorilyresistthepassageofrainandsnowtoinsidebuilding,support 10.1.9 Care shouldbetakentoensurethatgaragedoorsareinproperworkingorderathandover Proprietary doorsanddoorgearshouldbeinstalledinaccordancewiththemanufacturer Ease ofoperation Frames shouldbeselectedandfixedhavingtakenintoaccountthetypeweightofgaragedoor Robustness Doors andwindowswillbeacceptablewheretheyareinaccordancewithChapter6.7‘Doors,glazing’. a) Garage doorsandwindowsshallbeadequatefortheirpurpose.Issuestotakenintoaccountinclude: 10.1.8 Doors andwindows Where garagesofdifferent ownershiparelinked,wallsshouldpreventdirectaccessfromonegaragetoanother. garages arelinked. Garages shallbeconstructedtoprovidereasonablesecurityagainstunauthorisedentry 10.1.7 Security „ Chapter 7.1‘Flatroofsandbalconies’,or detailing atabutments bracing holding down robustness Garage roofs home garag wall fire-resisting e „ e) d) b) „ Chapter 7.2‘Pitchedroofs’. adequate disposalofrainwater. movement ease ofoperation. home garag partition fire-resisting e ’s recommendations. . fire-resisting ceilingorfloor CHAPTER 10.1 floor isfireresistin insulation requiredwhere Garages . , inparticularwhere g

2020 garage home . Nailing

4 4 10.1 , should have a 2 Wiring Regulations’. . ’s recommendations. ’s , with a total area greater than 6m risk of fire or explosion. provide appropriate weathertightness garages of provide adequate separation between linked ownership. different 8.1 ‘Internal services’. cavity trays that divert water from inside the cavity to the cavity trays that divert roof. external surface of the 7.2 ‘Pitched roofs’. „ „ „ „ „ c) „ „ „ „ „

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protection of water services against frost provision of electricity 5.3 ‘Drainage below ground’ 5.3 ‘Drainage below ground’ have appropriate foundations be structurally adequate 7.1 ‘Flat roofs and balconies’ 7.1 ‘Flat roofs and balconies’ flashings and weatherproofing that allow for flashings and weatherproofing movement differential from metal or other cover flashings formed approved material „ „ „ „ „ „ Permanent prefabricated garages and carports shall be suitable for their intended purpose. Permanent prefabricated garages should: Permanent prefabricated garages and carports All electrical installations should comply with BS 7671 ‘Requirements for Electrical Installations. IET All electrical installations should comply with BS 7671 ‘Requirements for Electrical Risk of fire or explosion be in accordance with any relevant statutory Installation in a garage of an oil or gas burning boiler or heating appliance should regulations. The provision of electric lighting and socket outlets in a garage is at the discretion of the builder The provision of electric lighting and socket outlets in a garage is at the discretion Provision of electricity A rising main should not be located within a garage. A down. water supply or outlet in a garage should have adequate provision for isolating and draining A Pipes should be insulated and located so as to minimise the risk of freezing. Protection of water services against frost a) b) Particular care should be taken to ensure adequate holding down of carports and other light structures against wind action. Particular care should be taken to ensure Services 10.1.11 in accordance with relevant regulations. The provision of any service or appliance within a garage shall be Issues to be taken into account include: Prefabricated garages should be erected in accordance with the manufacturer Prefabricated garages should be erected Permanent prefabricated garages and carports garages prefabricated Permanent 10.1.10 The provision of rainwater should be in accordance with building regulations. should be in accordance with building The provision of rainwater that drain from one to another Individual roofs, or combinations of roofs Adequate disposal of rainwater Adequate disposal Movement be provided with appropriate continued through roof coverings and foundations and the structure should be Movement joints in weather protection. Detailing at abutments Detailing garages, including: or between stepped the main building a garage roof and at abutments between should be taken Precautions rainwater drainage system. discharges onto a garage roof, precautions should be taken to prevent premature Where rainwater from a large roof surface erosion of the lower surface. roof directly to a drive or path. Rainwater should not discharge from the systems, reference should be made to the following chapters, as appropriate: For details on the design of rainwater disposal Where services or appliances are provided in garages, they should comply with the guidance below and with the following Where services or appliances are provided in garages, they should comply with chapters, as appropriate: „ „ „ „ „ „ 5

5 10.1 Drives, paths and landscaping CHAPTER 10.2

This chapter provides guidance on meeting the Technical Requirements for drives, paths and landscaping, including: „„private roads „„shared private drives „„private drives „„car parking areas.

10.2.1 Compliance 01 10.2.2 Provision of information 01 10.2.3 Stability 01 10.2.4 Freestanding walls and retaining structures 01 10.2.5 Guarding and steps 01 10.2.6 Drives, paths and landscaping 02 10.2.7 Materials 06 10.2.8 Garden areas within 3m of the home 07 10.2.9 Garden areas 07 10.2.10 Timber decking 07 10.2.11 Landscaping 07

Also see: Chapter 2.1 Also see: Technical a path is adjacent to a vertical difference in level of more a path is adjacent to a vertical difference than 600mm (including where ground adjacent to the path falls away at an angle of more than 30° from the horizontal). BRE Good Building Guide 14. the ground remediation statement (where applicable). the ground remediation „ „ „ This distance is measured from the external walls. This distance is measured

„ „ „ 2020

‘Design of concrete structures’. ‘Design of masonry structures’. ‘Geotechnical design. Ground investigation and testing’. ‘Building brickwork and blockwork retaining walls’. 10.2 CHAPTER Drives, paths and landscaping and paths Drives,

structures are retaining land more than 600mm high to which people have access a retaining structure is more than 600mm high and the dimension from the top of the retaining wall to the higher ground level is less than 300mm, or BS EN 1996-1 ‘Design of masonry structures’ the design, and „ „ „ „ BS EN 1992 BS EN 1996 BS EN 1997-2 BRE Good Building Guide 27 Retaining structures and steps shall be adequately guarded and allow safe use. Retaining structures and steps shall be adequately guarded and allow Guarding should be provided where: Guarding and steps Guarding 10.2.5 drainage systems. of the foundations of a home should be completed before work starts on the construction Retaining structures that give support to the foundations of the home. Retaining structures should be in accordance with: Freestanding walls and retaining structures shall be adequate for their intended purpose. Freestanding walls and retaining with: Freestanding walls should be in accordance Freestanding walls and retaining structures retaining and walls Freestanding 10.2.4 Where the ground may become surcharged during construction, precautions should be taken to ensure stability. Where the ground may become surcharged or be used to provide support to homes, garages, roads, drives, car parking areas Gabion and timber structures should not Stability 10.2.3 stability of the ground. Precautions shall be taken to ensure All works relating to drives, paths and landscaping should be fully specified. All works relating to drives, paths and landscaping to site supervisors, relevant specialist subcontractors and suppliers. Designs and specifications should be issued Provision of information of Provision 10.2.2 be produced in a clearly understandable format, include all relevant Designs and specifications shall the appropriate personnel. information and be distributed to All works should be completed in accordance with: All works should be be set out in accordance with the design. Formation levels should Drives, paths and landscaping that comply with the guidance in this chapter will generally be acceptable. that comply with the guidance Drives, paths and landscaping up to 20m is the land within the curtilage The ‘garden area’ flat or maisonette. bungalow, includes a house, In this chapter ‘home’ of the home (i.e. not garages/outbuildings). from the habitable parts 10.2.1 Compliance 10.2.1 Requirements. with the Technical shall comply and landscaping Drives, paths Requirement R5. in boundary situations, they should be designed Where timber structures more than 600mm high are used for retaining ground with a desired service life of 60 years. retained soil and the plant species. Where planters are provided, they should be designed to support the volume of All retaining structures, more than 600mm high, should be designed by an engineer in accordance with All retaining structures, more than 600mm high, should be designed by an engineer „ „ „ „ 1

1 10.2 „ „ „ „ „ „ „ „ „ „ „ „ Private roads,sharedprivatedrivesandshould: building regulations. accessible approachcanbefoundinsupportingdocumentsto Guidance fortheprovisionofhandrailstostepsthatforman steps islessthan600mm. external stepsismorethan600mmandthegoingofindividual A handrailshouldbeprovidedwherethetotalriseofaflight regulations should: External stepsthatarenotconsideredunderbuilding Finished groundlevelsshouldbecompatiblewith: Sub-bases shouldbemechanicallyconsolidatedinlayersnotexceeding225mm. up levels. Only suitablefillmaterialcomprisingclean,well-consolidatedcrushedrock,hardcore,slagorconcreteshouldbeused tomake All vegetablemattershouldberemovedfromtheareaofproposedworks. or othersuitablemeansofcollectionanddisposalisprovided). Where abuttingthehome,theyshouldbeatleast150mmbelowDPC,andlaidtofallsawayfromhome(unless achannel Private roads,sharedprivatedrives,carparkingareasandpathsshouldcomplywithrelevantbuilding regulations. General constructionconsiderations car parkingareasandpaths,asappropriate. Homes shouldbeprovidedwithsuitableaccessthroughtheprovisionofprivateroads,shareddrives, c) b) a) shall beprovidedtoandaroundthehome.Issuestakenintoaccountinclude: Appropriate access(includingprivateroads,shareddrives,carparkingand paths) 10.2.6 Drives, paths andlandscaping The guardingshould: „ „ „ „ „ „ „ „ „ „ „ „ of vehiclesgrounding. changes, havesuitabletransitionlengthstoreducetherisk where thegradientismorethan1:10and have amaximumgradientof1:6 parking area provide reasonableaccesstoandfromagarageorcar be appropriatefortheloads cover levelsofdrainageaccesspoints DPC levels be reasonablyuniform. have aminimumgoingof220mm have amaximumriseof220mm not allowa100mmdiameterspheretopassthrough. not bereadilyclimbablebychildren be aminimumof1100mm high construction details drainage general constructionconsiderations

Drives, paths andlandscaping

„ „ e) d) „ „ adjacent surfaces. water anddrains) depth ofundergroundservices(gas,electricity, house pathsandpatios. minimum sub-basethickness 11 00mm 500mm <300mm 500mm CHAPTER 10.2 ramp >600mm less than600mmofland) (even whereitisretaining from thelowergroundlevel wall ismorethan600mm where thetopofaretaining guarding mayberequired 500mm 500mm

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600 700 900 900 Minimum overall width (mm) 450 450 750 900 Minimum width of hard standing (mm) have surfaces with a minimum finished fall of 1:80 where have surfaces with a minimum finished they form private drives and paths or drain to a drain away from the home (and garage), and disposal channel or other suitable means of collection adjacent to the home not drain surface water from private areas onto not be within 2m of a soakaway. Where a garage, carport or car parking area is provided Where a garage, carport a path should be provided to it from within the curtilage, the home. adopted areas „ „ „ „ „ „ „ „ „ „ 2020

Suitable path widths

10.2 CHAPTER Drives, paths and landscaping and paths Drives,

have sub-base levels with the same longitudinal gradient and cross-fall as the finished level have surfaces not flatter than 1:40 or have a camber of 1:40 where no fall is available to avoid ‘flat spots’ have surfaces with adequate falls, cross-falls and drainage have surfaces with adequate falls, cross-falls drained to ensure that surface water is suitably have vertical alignment, finished levels, transition have vertical alignment, finished levels, with the design arrangements and gradients in accordance Where the secondary entrance is to a mid-terrace home or entrance is to a mid-terrace home or Where the secondary path to a secondary access door is not ground floor flat, a required. Where entry to the home can be gained directly from a Where entry to the home secondary access door is not required. garage, a path to a „ „ „ „ „ „ All other cases. Paths adjoining a home (with hard standing 100mm or more from the Paths adjoining a home (with hard standing wall of the home). Paths used for the removal of refuse to the collection point. Paths used for the removal of refuse to Within curtilage to main entrance, or any entrance designated by Within curtilage to main entrance, or any Building Regulations. Location and use Drainage private drives should have adequate rainwater drainage and disposal. Private roads, shared private drives and Paved areas should: Table 1: Table Where appropriate, a drive can be regarded as a path for the provision of access. a drive can be regarded as a path for the Where appropriate, 1:6. On steeper sloping ground, steps may be required. Paths should have a maximum slope of Underground drainage or services that are below a private road, shared private drive, private drive, car parking area, path or patio area, path or patio drive, car parking private drive, private a private road, shared that are below drainage or services Underground below ground’. in Chapter 5.3 ‘Drainage as described protected against damage, should be edge for the a permanent supporting is suitable to form foundation, which have a profile and or kerbing should Edge restraint on the road or drive. expected vehicle loads and the secondary curtilage of each home to the main entrance be provided via a path within the Pedestrian access should entrance where present: Where paving slabs are laid abutting drainage channels and gully grates, etc., the upper surface of the paving slab should be set Where paving slabs are laid abutting drainage channels and gully grates, etc., approximately 5mm above the grating. rainwater drainage system, reference should be Where it is intended to use porous or permeable surfaces as part, or all, of the and Wales. report C522 – Sustainable urban drainage systems design manual for England made to CIRIA „ „ „ „ „ „ 3

3 10.2 Table 2a: with thetablesbelow, oranequivalentalternative. The constructionofprivateroads,shareddrives,drivesandcarparkingareasshouldbeconstructedinaccordance Construction details Table 2b: Pavers Bedding course (wearing course) Surface course (road base) Base Sub-base (base course) Binder course Construction (road base) Base Construction Sub-base (base course) Binder course (wearing course) Surface course Bedding course Pavers Private roadhavingfrequentusebycommercialvehicles Shared parkingandassociatedaccessareashavingfrequentusebycommercialvehicles (1) (1) (weathering, abrasionandslip/skid classes) Block paverstoBS6717ofclass markingsW2, A2 andS3 Sharp sandtoBS7533-3categoryIIofannexD Concrete designation(BS8500-2:table6) Mastic asphalttoBS1447 Hot rolledasphalttoBS594-1 Concrete designation(BS8500-2:table6) bitumen) withcrushedrockaggregatetoBS4987(group2 mix) Dense bituminousmacadam(100/150penpavinggrade bitumen) withcrushedrockaggregatetoBS4987(group1 mix) Dense bituminousmacadam(100/150penpavinggrade MCHW Volume 1Series800 Granular sub-basematerialtype1toclause803table8/2 bitumen) withcrushedrockaggregatetoBS4987(group3 mix) Dense bituminousmacadam(100/150penpavinggrade (BS 8500-2:table6) Concrete designation aggregate toBS4987(group1mix) paving gradebitumen)withcrushedrock Dense bituminousmacadam(100/150pen Series 800 clause 803table8/2MCHWVolume 1 Granular sub-basematerialtype1to aggregate toBS4987(group2mix) paving gradebitumen)withcrushedrock Dense bituminousmacadam(100/150pen (BS 8500-2:table6) Concrete designation Mastic asphalttoBS1447 Hot rolledasphalttoBS594-1 aggregate toBS4987(group3mix) paving gradebitumen)withcrushedrock Dense bituminousmacadam(100/150pen annex D Sharp sandtoBS7533-3categoryIIof slip/skid classes) W2, A2 andS3(weathering,abrasion Block paverstoBS6717ofclassmarkings (2) (6)

(2) Drives, paths andlandscaping (6) Table 3 macadam) (bituminous Road Road type N/A N/A to clause5.2) 100 (0/32mmsize to clause6.5) 60 (0/20mmsize N/A 0/10mm size) 30 (gradeS–40% 30% 0/14) 40 (designation to clause7.4) 30 (0/10mmsize N/A

N/A N/A N/A N/A 100 gradeGEN2 clause 7.4) 30 (0/10mmsizeto clause 5.2) 80 (0/32mmsizeto clause 6.5) 60 (0/20mmsizeto N/A Table 3 Bituminous macadam Road type 5% = Table 3 Where CBRisgreaterthan = 150 Ratio (CBR)is5%orless Where CaliforniaBearing (block pavers) Road 80 N/A N/A clause 6.5) 60 (0/20mmsizeto N/A N/A N/A N/A 50 (3) CHAPTER 10.2 (4)

50 N/A N/A N/A N/A N/A N/A 80 Table 3 Block pavers N/A 225 macadam) (bituminous Footpath N/A N/A N/A clause 6.5) size to 60 (0/20mm N/A N/A N/A clause 7.5) size to 20 (0/6mm N/A

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4 4 10.2

N/A N/A N/A N/A Gravel 3 Table N/A N/A N/A N/A (7) Gravel 3 Table N/A N/A N/A N/A (7) N/A N/A N/A N/A N/A N/A N/A 50 Block pavers 3 Table N/A N/A N/A N/A 50 Block pavers 3 Table 80 N/A N/A N/A N/A N/A N/A N/A 50 N/A N/A 100 grade PAV 1 N/A Concrete 3 Table N/A N/A N/A N/A N/A Concrete 3 Table N/A N/A N/A N/A N/A N/A N/A 150 grade PAV2 N/A .

N/A N/A N/A N/A Road type Bituminous macadam 3 Table N/A N/A N/A 60 (0/20 mm size to clause 6.5) 20 (0/6mm size to clause 7.5) N/A Road type Bituminous macadam 3 Table (5) N/A 80 (0/32mm size to clause 6.4) or (0/20mm size to clause 6.5) 30 (0/10mm size to clause 7.4) 40 (designation 30% 0/14) S-40% 30 (grade 0/10mm size) N/A N/A or less and S4 is 45 or more based on ‘C scale unit’ (for abrasion, or less and S4 is 45 or more based on ‘C scale unit’ 2 ith BS 4987-2 or BS 594-2. ub-base. Where no geotextile membrane is provided, see Table 3. Table ub-base. Where no geotextile membrane is provided, see Volume 7 Section 2 Part 2 HD 25/95 Foundations Chapter 3 Capping and Volume n brackets. should be laid with one single row of stretcher bond set parallel to the edge 2020

(6) (6) (2) (2) Granular sub-base material type 1 to clause 803 table 8/2 Granular sub-base material 1 Series 800 MCHW Volume (100/150 pen paving grade Dense bituminous macadam mix) 1 (group 4987 BS to aggregate rock crushed with bitumen) Concrete designation (BS 8500-2: table 6) Concrete designation (100/150 pen paving grade Dense bituminous macadam mix) 2 (group 4987 BS to aggregate rock crushed with bitumen) (100/150 pen paving grade Dense bituminous macadam mix) 3 (group 4987 BS to aggregate rock crushed with bitumen) Hot rolled asphalt to BS 594-1 Hot rolled asphalt to BS 594-1 Mastic asphalt to BS 1447 6) Concrete designation (BS 8500-2: table annex D Sharp sand to BS 7533-3 category II of A2 and S3 W2, Block pavers to BS 6717 of class markings (weathering, abrasion and slip/skid classes) Mastic asphalt to BS 1447 Concrete designation (BS 8500-2: table 6) Sharp sand to BS 7533-3 category II of annex D A2 and S3 Block pavers to BS 6717 of class markings W2, (weathering, abrasion and slip/skid classes) Granular sub-base material type 1 to clause 803 table 8/2 Granular sub-base material type 1 to clause 1 Series 800 MCHW Volume paving grade Dense bituminous macadam (100/150 pen BS 4987 (group 1 mix) bitumen) with crushed rock aggregate to 6) Concrete designation (BS 8500-2: table Dense bituminous macadam (100/150 pen paving grade bitumen) with crushed rock aggregate to BS 4987 (group 2 mix) Dense bituminous macadam (100/150 pen paving grade bitumen) with crushed rock aggregate to BS 4987 (group 3 mix) (1) (1) Private drives and parking areas having use by cars and light vehicles Private drives and parking areas having Shared drives having infrequent use by commercial vehicles use by commercial having infrequent Shared drives 10.2 CHAPTER Drives, paths and landscaping and paths Drives,

class A2 = maximum result is 23mm, class A1 = no performance determined). A2 = maximum result is 23mm, class class EN 13242 (gravel), 38mm thickness of graded 15/20mm unbound aggregate to BS well rolled and compacted, should be used. A Thicknesses are in mm. Reference to clauses are in relation to the relevant British Standards. In the first column, European harmonised names are used and UK names are i Sub-base gives guidance on capping and sub-base thickness design based on CBR values with and without a capping layer Sub-base gives guidance on capping and sub-base thickness design based on CBR values with and Where a capping layer is specified, sub-base thickness can be reduced. DMRB restraint. Where block pavers are laid abutting drainage channels, gulley grates, etc. the upper surface of the block pavers should be set 3-6mm above the grating. restraint. Where block pavers are laid abutting drainage channels, gulley grates, etc. the upper surface Manufacturer’s declared value markings W3 and S4 are acceptable. Where W3 is 1.0 kg/m Bond and tack coat should be provided for bituminous mixtures in accordance w Asphalt-based materials can be used as a partial replacement of a full thickness granular sub-base type 1 material. Where laid to either a 90 or 45 degree herringbone pattern, the edge perimeter Thickness is based on the provision of a geotextile membrane underneath the s Sub-base Base (road base) Binder course (base course) Surface course (wearing course) Bedding course Pavers Bedding course Pavers Construction Construction Sub-base Base (road base) Binder course (base course) Surface course (wearing course) 7 8 9 Notes 1 2 Table 2d: Table Table 2c: Table 6 4 5 3 5

5 10.2 „ Exposure Assessment (CLEA) guidelinesprovideadviceondeterminingthesuitabilityof topsoil. Topsoil should beofaqualitythatwillnotpresenthazardtousers ofthegardenarea.BS3882andContaminatedLand Blocks, slabs,pavers,edgings,etc.shouldcomplywithrelevant standards,including: with relevantstandards,including: Aggregates used aggregate (graded15/20mmgravel)for in asphaltandmacadammixturesunbound surfacing shouldcomply Table 3: been carriedout,withconsiderationtothe: The thicknessofanyrequiredcappinglayerandthesub-baseshouldbedeterminedafterinvestigationson-sitetestshave Minimum sub-basethickness Hot rolledandmasticasphaltsmacadamshouldcomplywithrelevantstandards,including: Sub-base materialshouldbetype1toclause803 Table 8/2,MCHWVolume ISeries800. frost action. sufficient strengthforitspurposeandbesufficientlydurabletoremainunaffectedbychemicalor Materials shallbesuitablefortheirintendeduse.Concreteofamixdesignwhichwillachieve 10.2.7 Materials joint isnotrequiredattheabutmentwithawallunlessoppositeedgeofconcretealsorestrained. joints, notlessthan10mmwide,shouldbeprovidedacrossthefullwidthofpathatmore4mcentres. be suitabletogiveadurableandfrostresistantsurface,asdescribedinChapter3.1‘Concreteitsreinforcement’. Movement Concrete pathsandpatiosshouldbenotlessthan75mmthickhaveatampedortexturedfinish. hardcore (maximumsize75mm),slagorconcrete,andlaidon25mmofsandblinding1:4cement:sandmortar Paths andpatiosshouldbesupportedonasuitablesub-basesuchas100mmthicknessofclean,wellconsolidatedcrushed rock, House pathsandpatios BS 7533 BS EN1339 BS EN1344 BS EN771 PD 6682-6 BS EN13242 PD 6682-2 BS EN13043 BS EN13108-4 BS EN13108-1 CBR values Less than2% 2-3% 3-5% 5-7% 7-20% „ CBR value Minimum sub-basethicknessforpavedareas

‘Pavements constructedwithclay, naturalstoneorconcretepavers’. ‘Concrete pavingflags.Requirementsandtestmethods’. ‘Clay pavers.Requirementsandtestmethods’. ‘Specification formasonryunits’. ‘Guidance ontheuseofBSEN13242’. ‘Aggregates forunboundandhydraulicallyboundmaterials’. ‘Guidance ontheuseofBSEN13043’. ‘Aggregates forbituminousmixturesandsurfacetreatments forroads,airfieldsandothertraffickedareas’. ‘Bituminous mixtures.Materialspecifications.HotRolled Asphalt’. ‘Bituminous mixtures.Materialspecifications. AsphaltConcrete’. Without geotextileunderneath (consolidated inaccordancewithMCHWVolume 1clause801,table8/1) Minimum thickness(mm)ofsub-base N/A 325 250 150 100 Drives, paths andlandscaping „ „ be affected byfrostheave. the sub-basetoadepthensurethatconstructionwillnot to frost,asuitablecappinglayershouldbeincludedbelow frost susceptibilityofthesub-grade;wheresusceptible

With geotextileunderneath 300 225 150 N/A N/A CHAPTER 10.2 The concretemixshould . A movement

2020

6 6 10.2

Technical Technical Also see: Chapter 3.3 designed by an engineer in accordance with Unsupported cohesive soil should not exceed 9° (1:6). Unsupported cohesive soil should not exceed to conform ground disturbed during construction re-graded to the general shape of the adjacent ground Topsoil provided. a minimum thickness of 100mm topsoil may present a should not contain contaminants which should be hazard to the occupants. Disturbed topsoil reinstated. Requirement R5. Technical „ „ „ „ „ „ „ „ 2020

10.2 CHAPTER Drives, paths and landscaping and paths Drives,

Timber Decking Association, or Decking Timber in accordance with guidance published by the appropriate action, such as rotavating, undertaken to restore appropriate action, such as rotavating, has been compacted the drainage characteristics of soil that during construction old foundations, concrete bases and similar obstructions old foundations, concrete bases and similar removed within 300mm of the finished ground surface Unsupported granular soil should be 5° less than its natural Unsupported granular soil should be 5° angle of repose. „ „ „ „ Where trees or shrubs have been removed, are to be retained or are to be planted by the builder, precautions should be taken to by the builder, Where trees or shrubs have been removed, are to be retained or are to be planted 4.2 ‘Building near trees’. reduce the risk of future damage to homes and services in accordance with Chapter 10.2.11 Landscaping 10.2.11 and layout. Possible future Planting shall be completed in a manner appropriate for the site conditions damage to the home caused by planting shall be minimised. Decking that is more than 600mm above ground level should be: Patios and decking shall be suitable for their purpose. Patios and decking shall be suitable decking, including support, should be naturally durable or treated with preservative. Timber Timber decking Timber 10.2.10 Subsoil should not be placed over topsoil. Construction rubbish and debris should be removed from the garden and other areas Construction rubbish and debris should be removed from the garden and other Subsoil should not be placed over topsoil. around the home. but garden areas, such as narrow strips of land at the top or bottom of retaining walls, Access is not required to small isolated appropriate by steps or other suitable means. should be provided to other areas where Garden areas within 20m of habitable accommodation shall be adequately prepared, stable and provided shall be adequately prepared, 20m of habitable accommodation Garden areas within access. with reasonable with be determined by an engineer in accordance or existing slopes in garden areas should The stability of new following maximum gradients should apply: the Alternatively, Requirement R5. Garden areas Garden 10.2.9 Waterlogging of garden areas within 3m of the habitable parts of the home should be prevented by drainage or other suitable of the home should be prevented by drainage areas within 3m of the habitable parts of garden Waterlogging means. Garden areas within 3m of the home 3m of within areas Garden 10.2.8 up to 3m from the the home areas around and utility immediately access to to provide for adequate In order the home shall not be waterlogged. habitable parts of Garden areas should have: „ „ „ „ 7

7 10.2 NHBC is authorised by the Prudential Regulation Authority and regulated by the Financial Conduct Authority and the Prudential Regulation Authority.

NHBC is registered in England under company number 00320784. NHBC’s registered address is NHBC House, Davy Avenue, Knowlhill, Milton Keynes, Bucks MK5 8FP.

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