Design Guide - JPA TL

1 Design GuideConcrete block masonryCI/SfBFfNovember 19972 Topblock Design GuideThis Topblock Design Guidecontains detailed informationon the Design and performance ofconstructions using Topblockproducts. It draws upon Topblock sunrivalled experience, making it aninvaluable reference Guide will assist in the Design of blockwork to meet projectrequirements, in compliance with building regulations,British Standards andindustry codes of practice. The blockwork solutions presentedhere incorporate the latest researchinto concrete blockworkperformance. Five key aspects ofblockwork masonry performanceare dealt with:- thermal performance, acoustic performance, structural Design , movement control, includes guidance on the safehandling of blocks for both thespecification and sitework phases of product information,including the performancecharacteristics of Topblock products, isgiven in the individualproduct Guideconcrete block masonry1.

2 Thermal Requirements of Building Heat Thermal Limiting air Calculating U Wall Floor solutions172. Acoustic Internal Sound Sound absorption253. Structural Design Unreinforced Reinforced Diaphragm walls324. Movement The causes of Provision for Summary385. Frost Sulphate resistance436. Block Regulations and Safe handling of blocks453 ContentsTopblock Design Requirements ofBuilding RegulationsBuilding Regulation L1 requiresreasonable provision be made forthe conservation of fuel and powerin buildings. The ApprovedDocument to Regulation L1 sets outways of meeting the requirementsfor energy efficiency for new buildand refurbishment projects. Thoseaspects which affect the Design andspecification of blockwork include: insulation of the building fabric; thermal bridging at openings; limitation of air thermal performancerequirements apply to: dwellings; other buildings with total floorarea exceeding are two main exclusions fromthe requirements: intended to have lowlevels of heating do not have tocomply with the requirements:low level heating is defined as anoutput of: not more than 50W/m2floorarea for industrial or storagebuildings; not more than 25W/m2floorarea for buildings other thandwellings.

3 (Where the eventual level ofheating is not known at the timeof construction, the building mustbe designed to comply with therequirements.) a small extension notexceeding 10m2in total floor area,reasonable provision is deemed tobe achieved if it reaches the samelevel of effectiveness as theexisting Heat DwellingsRegulation 14A of the BuildingRegulations requires thepreparation of an energy rating forall dwellings which are new build orcreated by the material change ofuse of an existing building: therating must be calculated using theStandard Assessment Procedure(SAP). Guidance on calculating SAPratings is given in ApprovedDocument L, Appendix are three methods fordemonstrating compliance with therequirement to limit heat lossthrough the building fabric:- Elemental method; Target U value method; Energy Rating method:any one of those methods may be Design Guide1.

4 Thermal Elemental methodTo demonstrate compliance usingthis method elemental U valuesmust not exceed those given intable The U values shown incolumn (a) apply to dwellings witha SAP Energy Rating of 60 or the SAP rating exceeds 60,the U values in column (b) shouldbe Target U value methodTo demonstrate compliance usingthis method the average U value ofthe dwelling must not exceed thecalculated Target U Target U value is calculated as:for dwellings with SAP Rating of 60or less and asfor dwellings with SAP Energy Rating of more than 60 The average U value is calculatedas:This method allows designers totrade-off the thermal performanceof different elements and to takeaccount of benefits from improvedheating efficiency and solar Energy Rating methodTo demonstrate compliance usingthis method the SAP rating of thedwelling must not be less than theappropriate value shown in table floor area (m2)855 Topblock Design Guide80 or lessMore than 80 up to 90 SAP Energy Rating8081 More than 90 up to 10082 More than 100 up to 11083 More than 110 up to 12084 More than 120 Table : SAP values for the Energy Rating methodTotal heat lossTotal area of exposed elementsTotal floor area x + area of exposed elementsTotal floor area x + area of exposed elementsExposed wallsElementFor SAP energy ratings of60 or less: (a)over 60.

5 (b) floors and ground * **Semi-exposed walls and , doors and rooflights** : Standard U values (W/m2K) for dwellingsNotes*Any part of a roof having a pitch of 70 or more may have the same U value as a wall.**For rooms in the roof, or flat roof construction a U value of acceptable to dwellings.**The U values given for windows, doors and rooflights ( or ) are based on a combined area not exceeding of total floor area. However, some flexibility is possible, for example, if improved performance units are used a corresponding increase in area is Buildings other thandwellingsThere are three methods fordemonstrating compliance with therequirement to limit heat lossthrough the building fabric:- Elemental method; Calculation method; Energy Use method:any one of those methods may be Elemental methodTo demonstrate compliance usingthis method elemental U valuesmust not exceed those given intable area of glazing must not exceedthe values given in table unlessthere is a compensatingimprovement in the performance of the glazed Calculation methodTo demonstrate compliance usingthis method the rate of heat lossfrom a proposed building must beno greater than that from a notionalbuilding of the same size and shapewhich has been shown to complyusing the Elemental method.

6 This allows greater flexibility thanthe Elemental method as theU values of elements may be variedwithin the prescribed limits (see ). Energy Use methodTo demonstrate compliance usingthis method the annual energy useof the proposed building must beno more than a similar buildingwhich has been shown to complyusing the Elemental method. This permits the designer to use any valid energy conservationmeasure and to take account ofsolar and internal heat Limiting U valuesFor compliance methods other thanthe Elemental method, the U valuesof exposed building elements mustnot exceed the limiting valuesshown in table *Display windows and shop entrance doors are excludedNotes*Any part of a roof having a pitch of 70 or more may have the same U value as a wall.**To buildings comprising a flat roof or insulated sloping roof with no loft space, a U value of will be acceptable or for residential Design GuideBuilding typeResidential including hotels andinstitutional buildings Places of assembly, offices and shopsIndustrial and storage buildingsVehicle access doorsWindows and doorsRooflights30% exposed wall area20% of roof area40% exposed wall area*15% exposed wall areaAs requiredTable : Basic allowance for windows, doors and rooflightsExposed wallsExposed floors and ground floorsRoofs*Semi-exposed walls and floorsWindows, doors and rooflightsVehicle access and similar large ** : Standard U values (W/m2K) for buildings other than dwellingsDwellingsResidential buildingsOtherbuildingsLimiting U values (W/m2K).

7 Limiting U values forexposed Thermal bridgingThermal bridging can occur aroundwindows and doors, increasing heatloss and leading to localised surfacecondensation. Approved Document L shows anumber of recommended methodsof avoiding thermal bridging(reproduced in figure ) as well as a number of alternatives (see Appendix D of the Approved Document). A method of calculating the effectof thermal bridging is given in BRE Information Paper 12/94 Assessing condensation risk and heat loss at thermal bridgesaround openings .7 Topblock Design GuideNotes1 The thermal conductivity of the blockwork should not exceed (eg Toplite Standard) and the frame should overlap the blockwork by at least 30mm for drylining or alternatively 55mm for lightweight internal faces of metal lintels should be covered with at least 15mm of lightweight plaster; alternatively they can be drylinedInsulating blockwork1 Internal insulationPartial cavity fill2 Full cavity fill2 Figure Reducingthermal bridging around openingsCavities and Limiting airinfiltrationApproved Document L containsrecommendations for limiting theinfiltration of cold external air intobuildings: they consist mainly ofsealing potential gaps in theconstruction.

8 Dry linings to wallsshould be sealed at the perimetersof openings and at floors andceilings by using continuous bandsof plaster or fixing Calculating U valuesU values may be calculated by usingthe tabular method given inApproved Document L,Appendix A, or by the proportionalarea method given in Appendix methods take account of theeffects of repeating thermal recommend calculation on thebasis of known material sizes andproperties as this will result in a moreeconomical bridging effect of mortar jointsin blockwork need be consideredonly when the difference in thermalresistance between block and mortaris greater than Thus forcalculation purposes, walls ofTopcrete or of certain sizes ofHemelite and Lignacite may betreated as homogeneous floor U values may becalculated using the Perimeter/Area method (see ApprovedDocument L, Appendix C).

9 The area of the floor should bemeasured between the finishedinternal faces of the buildingand should include non-usablespace such as stairwells and builders Wall solutionsThe following tables cover theconstructions most likely to be used in the Design of external walls. Where U values have been shownwith no finish (NF) the tables assumethe use of Paint Quality or Fair Faceblocks, where those form part of theproduct range: Toplite blocks areavailable only in a keyed and Topcrete blocks maybe solid, cellular or U values have been calculatedfollowing the recommendations ofApproved Document L and usingthe material and airspace valuesshown in table and All blocks are assumedto have a face size of 440 215mmwith 10mm thick mortar Design GuideGeneral materialsFacing brickMortarRenderDense plasterLightweight plaster orplasterboardInsulation50mmCrown Dritherm full-fill65mm75mmRockwool cavity battsJablite cavity partial fillRockwool HP partial fillWallmate CWCelotex double-R CW2000 Thermal conductivity(W/mK).

10 Conductivities of materialsCavity high emissivityCavity low emissivity10mm airspace behind plasterboard25mm airspace behind foil-backed plasterboardThermalresistance(m2K/W) : Resistance values of airspaces9 Topblock Design GuideU Values (W/m2K) Insulation & Surface FinishDPNF50mm Rockwool Batts = Rockwool Batts = 0.