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One hour CIAT-accredited CPD Seminar for architecture and construction professionals
Loft insulation isn’t working in 80% of UK houses:
What can we do about it?
• Lo#Insula+onRegula+onsandStandards,Installa+onMethodandMarketPenetra+on
• ‘In-UseFactors’whichdiminishinsula+onperformance,includingCarbonTrustsurveyonlo#usage
• Theeffectoflo#insula+oncompressiononU-values• Safetyrequirementsinlo#s,includingRoSPAlo#accidentsta+s+cs• Tradi+onalinsula+onandbuildingmethods,whicharenolongerappropriate
• Alterna+vetechniquestomaximiseinsula+onperformance• Specificdesignconsidera+onsandU-valuecalculator• Summary• TestQues+ons
Orderofcontentofseminar
• Onaverage,25%ofabuilding’sheatlossthroughitsinsulatedexternalenvelopeisthroughtheroof(source:EnergySavingsTrust)
Lo0insula3on:whyit’sneeded
Typeofapplica3on RequiredU-valueforthelo0ceiling(W/m2K)
Requiredthicknessofthermalconduc3vityinsula3oniflaidattheceilingofthelo0
Newbuild U=0.13(EW&NIBRADL1A)U=0.11(ScotlandSTS6.2)
340mm400mm
Retrofit U=0.16(EW&NIBRADL1B)U=0.13(ScotlandSTS6.2)
270mm340mm
• Thisassumesthatmineralfibreinsula+onisusedwithathermalconduc+vitykvalueof0.044W/mK(asfoundinthemostcommonproducts)
• Itispossibletoreduceinsula+onthicknessesbyusingothermaterials• Itisalsopossibletoinsulateabove,betweenand/orbelowthepitchedroof
ra#ers;thiscreatesa‘warmlo#’.Warmlo#sarenotthesubjectofthispresenta+on.
Lo0insula3on:BuildingsRegula3onsandTechnicalStandards
Note:Don’tForgetOverhea3ng• Mineralfibreorplas+cthermalconduc+vityinsula+onkeepsheatinduring
winter.but– Doesnotreadilyletheatoutinthesummer– Doesnotpreventradiantsolarheatfromenteringthepropertyinthesummer
either– Inbothcases,leadingtopoten+aloverhea+ng,affec+ng20%ofhousing
(source:ZeroCarbonHomes)• Considerlo#insula+onwiththeaddi+onalpropertyofhighdecrementdelay/
thermalmass,including:– Cellulosefibreflake(recyclednewspaper)
• easyinstalla+onaroundanyframing– Corkgranules(easyinstalla+on)orboards– Woodfibrebaisorboards– Otherplantfibreinsula+onmaterialsinvariousformats
• ThisisthesubjectofaseparateCPDseminarbyGreenBuildingEncyclopaedia.Contact:forCPD
Step1:layinsula+onbetweenthejoists(usually75or100mmtall)
Step2:rollanotherlayerat90degreestothefirstlayer,togivethetotalrequiredthickness
Thicklo0insula3on:installa3onmethod
• Ofthe23milliondomes+clo#sintheUK:• 15millionhave>100mmofinsula+on
(Source:DECC,2016)• Thevastmajorityhavebeeninsulatedusingmineralfibrerolls,usually
selectedforcheapnessandeaseofinstalla+on• Manyothermaterialsareavailable,whethernatural,non-natural,virgin
orrecycled/re-used.• Othersformatsinclude:loose,blownorsprayedinsula+on,rigidboard
insula+onandmul+-foils• AnsimplecomparisoncanbefoundatSuperhomesandmoredetailed
comparisonsareavailableuponrequestfromLo#Zone.
Lo0insula3on:marketpenetra3on
• Unfortunatelyno,theperformanceisspoiledby:– Significant‘In-UseFactors’,whichmeansthatlo#insula+ondoesnotworkas
wellasitwasdesignedto
• Assumingthattheinsula+onhasbeenfiiedcorrectly,accordingtoPAS2030guidelines:– Withoutgapsand– Perminngcross-ven+la+onateaves
• Thenthe‘In-UseFactors’onthefollowingslidecomeintoplay
Islo0insula3on“fitandforget”?
• Compressionofthelo#insula+ondowntojoistheight– Storageofbelongingsdirectlyontopoftheinsula+on– Placinglo#boardsontothejoists
• Safeaccessdecksinstalledinthelo#,bearingontheceilingjoists– Usuallywellbelowtherequiredthicknessofinsula+on– Compressingtheinsula+onaboveandbetweenthejoists
• Thermalbridgingthroughtheceilingjoists,especiallyifthejoistshavebeenbuiltup,throughtheuseofcross-baiening
• Householderormaintenancecontractorac+on– e.g.movingtheinsula+onawaytocreatesafeaccesspathwaysandthennot
beingabletoreplaceitproperly,oratall• A#erbecomingmoistfromcondensa+onbuildupinthelo#:
– Insula+ondeteriora+on– Performancedropoff
SomeCommonIn-UseFactors:
• Windscourorwindwashingattheeavesandalongthetopoftheinsula+on,drawingheatoutoftheinsula+onsurface
• Verminaiack• Wildlifeinhabita+ondisplacingortunnellingthroughinsula+on• Accumula+onofdustanddebris,especiallya#erroofingwork• Wateringressthrougholdorleakyroofcoverings
SomeLess-CommonIn-UseFactors:
• TestsundertakenbytheNa+onalPhysicalLaboratoryshowedthatcompressingmineralfibrelo#insula+on:– affectstheUvalue– isverysignificant– Ismuchworsethanpreviouslythought
• Compressing270mmto75mm/100mm(typicaljoistheights):
Thebiggest‘In-UseFactor’islo0insula3oncompression
Thickness 270mm 100mm 75mm
Thermalresistancem2K/W 6.11 3.09 2.42
U-ValueW/m2K 0.164 0.324 0.413
Increaseinheatlost - 98% 152%
ObviousexamplesofIn-UseCompression• Storageofbelongings:directlyontotheinsula+on,orondeckingres+ngon
thejoists–inbothcasessquashingtheinsula+on
• Fromathermalconduc+vityinsula+onperspec+ve,thislo#ispoor(atleastinthecentralarea)
• Assumingthereisinsula+onundertheboards,thenitisonlyasdeepasthejoists,anditmaywellhavebeensquashedfromtheBuildingStandardsthicknessdowntojoistheight–whichatleastdoublestheheatlost
Lessobvious,butequallybad
• BothBuildingRegula+onsApprovedDocumentATable4(seebelow)andBS5268:Part3formoderntrussedra#erroofsrequirethelo#ceilingtosupport:– 0.25kN/m2distributedimposedload(forstorage)
• (1/8thoftheloadingforadomes+cfloor)– 0.90kNconcentratedpointload(forapersonaccessinglo#,assumedtobethe
loadthroughoneperson’sleg)• Lightstorageisthereforepermissible,
eventhoughmanybuilderstelltheoccupantsotherwise
• Notethatmanytradi+onalin-situcut+mberroofsareo#enmuchstrongerthantrussedra#erroofs
Myth1:Moderntruss-ra0erroofsarenotdesignedforstorageinthelo0
• Actually,theoppositeisoverwhelminglytrue:– 78%ofUKhouseholderssaylo#storageis“veryimportant”or
“essen+al”– 82%usetheirlo#sforstorage
• Ofthose,78%saytheirsismorethanhalffull– Only26%knowthatsquashinginsula+onisbadforit(Source:CarbonTrustsurvey,BiggesteversurveyofUKloFusers(6,000responses),2012)
• 69%ofpeopleinfullyoccupiedhomesdonothaveenoughspaceforstorage(Source:CABE,HATC,IpsosMori,quotedinRIBA“CaseforSpace”report,2011)
Myth2:Peoplecanbepersuadednottousetheirlo0forstorage
• Es+mated1,500hospitalvisitseachyearintheUKowingto:– fallsfromlo#s– fallsthroughlo#ceilings(Source:RoSPA,basedonlatestavailablesurveyfiguresforA&Edepartments.DataexcludesfataliTes)
• Architectsandbuildershavearequirementtodesign-insafemaintenanceunderCDM2015
• Landlordshavea‘DutyofCare’totheirmaintenancestaff
Safetyinlo0sisalsoanimportantissue:
• Coldwaterstoragetank,ballvalve,watersupplyanddeliverypipes,insula+onandoverflowpipe
• Boilertop-uptank,ballvalve,watersupplyanddeliverypipes,insula+onandoverflowpipe
• Boilerfuelandpowersupply,flues,pipesandinsula+on
• CommunalorDistricthea+ngflowandreturnpipesandinsula+oniffiied
• Hotwatercylinderorsolarcylinder,ballvalve,watersupply,overflowanddeliverypipes,andinsula+on
• Solarthermalpanelexpansiontank,pipesandinsula+on
• SolarPVinverterandcables
• PowerShowerPumps• Extractorfansandducts• MVHRMechanicalVen+la+onwithHeat
Recoveryduc+ng• Poweranddatacablesandconduit• Pipeworkandinsula+on• TVaerial,satellitedish,cableboxand
cables• Domes+csprinklersystempipeworkand
insula+on• Smokedetectorsandcables• WardenCallsystems• Ceilingmounteddownlighters• Ceilingmountedfans• Ceilingmountedaircondi+oningunits
Safelo0accessisrequiredtoservices:
Safeaccesspla]ormscanbethecauseoftop-upinsula3onremovalorcompression
Lo0insula3oncompressionisalimi3ngfactorinmee3ngtheUK’scarbontargets
• Theenergyusedbydomes+cbuildingsintheUKaccountsforapproximately25%oftheUK’stotalemissions(Source:CarbonTrust)
• Andyetwenowseethatlo#insula+onperformsbadlyinsomanybuildings
Ofgemandindependentresearchquan3fica3onoftheIn-UseFactors
• OfgemassumesthatIUFsreducetheeffec+venessoflo#insula+onby35%.Forexample,thisismandatedinlegisla+onfortheECOscheme(Source:ECOMeasuresTable)
• SubsequentresearchcollatedbyLo#Zoneshowsthistobeanunderes+mate,since27.5%isforlo#insula+oncompressionalone(Source:WhitePaperonLoFInsulaTonIUFs)
Sowhatarethesolu3ons?• Raising+mberpaneldeckingabove
exis+ngjoistswithso#woodframingorjoists?
• Deckingontopofrigidfoamed-plas+c
boards?
• Proprietarysupportsanddeckingsystems?
Cross-Ba^eningusedtobecommon
• Theextra+mberis:– Heavyandawkwardtogetinandfitinaconfinedspace– Itmayuseupasignificantpropor+onoftheloadbearingcapacityofthelo#
floor– Unabletocopewithunevenjoistheights–theresul+ngdeckwillbeuneven– Unabletocopewithservices(e.g.pipes)laidontopofthejoists–thesegetin
thewayofthenew+mber• Installersmustremembertoputbackinplaceanyexis+ngtop-upthermal
conduc+vityinsula+onbeforedeckingover• Takingcaretofitgap-freeinsula+onaroundframingorjoists• O#enhardtoinspectforqualityofworkoncetheboardshavebeenscrewedon
top
Butraising3mberpaneldeckingonso0woodframing/joistsisnolongergoodprac3ce
• Theextra+mberactsasathermalbridgethroughtheinsula+on– Linear(ifontopofjoists)orPoint(iflaidatrightanglestoexis+ngjoists)
• PartL1Aofthe2013BuildingRegula+onsinEnglandandWalesmandatethatPsivaluesforthesethermalbridgeshavetobeallowedforintheU-valuecalcula+onfortheroof
• Thiswillrequireanincreaseinthermalconduc+vityinsula+onthicknesstocompensate– Ifthereisnoroominthelo#loca+on,itwillbeneededelsewhere
WatchoutforPartL1Aofthe2013BuildingsRegula3ons!
Deckingontorigidfoamedplas3cinsula3on?
• Foamedplas+csinsula+onarenotnormallymoisturepermeablesovapourbarriersareessen+al-butdifficulttoaddtoexis+ngceilings
• Thelackofavapourbarriercancauseinters++alorsurfacecondensa+on,asmoistairpassingthroughtheceilinginsula+onwillcoolandmaycondenseontheundersideofthedeckboard
• Forconven+onalpitchedroofcross-ven+la+onitisrecommendedthatthereisatleastanadequateairgapbetweenthetopoftheinsula+onandtheundersideofthedeckingboard(source:BRE)– Thismeansthataddi+onal+mbermustbeusedtoraisethedeckingabove
therigidinsula+on.Butthishasthesameproblemascross-baiening.
Risksassociatedwithusingrigidfoamedplas3csinsula3on(1)
• Rigidfoamedplas+csinsula+onmustnotbeallowedtotouchplas+cconduitorplas+csheathingofelectricalcables– Polymermigra+onmaymodifytheperformanceofbothplas+cs
• Plas+cscandissolveaway– Atpar+cularriskareexpandedorextrudedpolystyrenerigidfoamedplas+c
orrigidboardinsula+on,andpolyurethanesprayfoam– Thereismoreinforma+oninatechnicalpaperon“
Themigra+onofplas+cisersfromPVCcablesheathingintoexpandedpolystyreneinsula+on”.
• Finally,onaprac+calpoint,largesec+onsofrigidinsula+on/deckingarealsohardtogetthroughthelo#hatchandfitwithinaconfinedlo#space,withoutgaps
Risksassociatedwithusingrigidfoamedplas3csinsula3on(2)
• Overaperiodofyearstherewasareac+onbetweentheplas+ciserinthePVCcablingandthepolystyreneinsula+on,wherebytheplas+cisermigratedoutofthePVC,so#eningthestyrenewhichadheredtothePVC,leavingabriilecablethatcrackedandsplit,exposing
Exampleoffirecausedbypolymermigra3on
liveconductorswhichcausedafireinvolvingthe+mberswithinthelo#space.(Source:EastSussexFireandRescueService)
• Thereareanumberofnewproductsandsystemsonthemarket• OnlyonesystemhasbeenapprovedbyBBAforuseinconstruc+on:
– Itisstrongenoughtowithstandtherequiredloading– Itistallenoughtomeetmostmoderninsula+onthicknesses– Itavoidscrea+ngasignificantthermalbridgethroughtheinsula+on– Ithasaven+la+ongaptoavoidsurfaceorinters++alcondensa+on
• ThatsystemisLo#ZoneStoreFloor(www.lo#zone.co.uk)• BBACer+ficate15/5269
Newraisedlo0deckingsystems
Lo0ZoneStoreFloor:plas3csupportsandmetalbeamstoraise3mberpaneldecking
Lo0ZoneStoreFloorinstalla3ons(1)
Lo0ZoneStoreFloorinstalla3ons(2)• Innewbuildtruss-roofresiden+alproper+es
Lo0ZoneStoreFloorinstalla3ons(3)• Alsousedforsafeaccesswalkwaysinnon-domes+cbuildings
DesignConsidera3on1:DoestheLo0Zonesystemcauseasignificantthermalbridge
throughitssupports?
• Noitdoesnot.TheBuildingsResearchEstablishmentcalculatedthatthethermalconduc+vitythroughtheplas+csupportswasnegligible,becauseoftheirmaterialchoiceandbecauseofthesmallcontactareas
• TheyneednotbeconsideredinU-valuecalcula+ons• Seenextslideforscreenshotfromthereport
Thermalbridgethroughsupports?
DesignConsidera3on2:SizeofVen3la3onGap• Theven+la+ongapneededtoreducetheriskofinters++alcondensa+onis
dependentonthehumidityoftheairandtheven+la+onlevelsinthelo#• 50mmbetweenthetopoftheinsula+onandtheundersideofthedecking
boardsisdefaultprac+ceandrecommendedbyBBA• BREcalculatedthata29mmven+la+ongapwouldbesufficient,solongas
therewasadequateven+la+oninthelo#(e.g.fromtheeaves)• TheLo#Zonesupportsare279mmtallandareplacedontotheexis+ngjoists
(whichareusually75mmor100mmtall).Thisgivesupto350mmdepthforinsula+onplusa29mmair-gap.Shouldtheinsula+onlevelsbedeeper,thentheLo#Zonesupportswouldberaisedupwithsmallsec+onsof+mberdirectlyunderneaththesupport(noneedtocross-baienhowever).
Client Report: Hygrothermal assessment of LoftZone floor Client report number 275586 Prepared for: Pier Cave LoftZone Ltd 28 November 2011
ToolforDesigners:GBECalculator
• ThereisafreetoolfordesignerstoselectrequiredmaterialschoicesandcalculateU-valueswhenlo#deckingisneeded
• GBECalculatorLo#ZoneStoreFloorUValueA05BRM100117XLSX(linkopensExceldocument)
• Lo#insula+on‘In-UseFactors’,inpar+cularcompression,areamajorissue• Significantnumbersofhousesareaffected,addingconsiderablytoUK
energyandfueldemandsandcarbonoutputsofUKhousing• Storagespaceishighlyimportantinbuildings• Safeaccesstothelo#formaintenancepurposesneedstobedesignedinby
architectsandbuilders• Mosttradi+onalmeansofsolvingtheneedforstoragespaceandsafe
accesswalkwaysarenolongergoodprac+ce• TheLo#ZoneStoreFlooristheonlyproductforthispurposethathasbeen
approvedbyBBAforuseinconstruc+on.
Summary
1. Whatpercentageofhouseholdsusetheirlo#forstorage?(35%,50%,82%)2. Iflo#insula+oniscompressedfrom270mmto100mmjoistheight,byhow
muchdoestheU-valuechange?(Ithalves,itdoubles,itstaysthesame)3. WhatisthegaprecommendedbyBREbetweenthetopoftheinsula+onand
theboiomofthedeck,topreventsurfacecondensa+onontheundersideofthedeckboards,assumingadequateven+la+oninthelo#?(29mm,50mm,82mm).
4. WhatdoesOfgemconsiderthetotalreduc+onintheeffec+venessofUKlo#insula+onowingtoallIn-UseFactorstobe?(35%,50%,82%)
5. Whatistherequirementfortheloadingoftheboiomchordoftrussedra#erroofs?(0.25kN/m2distributedimposedloadplus0.90kNconcentratedpointload0.50kN/m2distributedimposedloadplus0.90kNconcentratedpointload0.82kN/m2distributedimposedloadplus0.90kNconcentratedpointload)
6. Underwhichregula+onsarearchitectsandbuildersrequiredtodesigninsafemaintenanceaccess?(PartL1A,WorkingatHeightRegula+ons,CDM2015)
TestQues3ons:
1. 82%ofhouseholdsusetheirlo#sforstorage2. Uvaluedoubleswheninsula+oncompressed270to100mm3. 29mmcross-ven+la+ongapisrecommendedbyBRE4. Ofgemconsider‘In-usefactors’reduceUKlo#insula+oneffec+venessby
35%5. 0.25kN/m2distributedimposedloadplus0.90kNconcentratedpointload6. CDM2015requiressafemaintenanceaccesstobedesignedin
TestAnswers: