Insulation: Selection And Installation

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Title:
Insulation: Selection And Installation
Physical Description:
Fact sheet
Creator:
Cook, Gary D.
Publisher:
University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication:
Gainesville, Fla.
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Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
Publication Status:
Published
General Note:
"First published: October 1985. Revised: March 1995."
General Note:
"EES-25"

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University of Florida Institutional Repository
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University of Florida
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All rights reserved by the submitter.
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IR00004792:00001


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FactSheetEES-25 Insulation:SelectionandInstallation1 GaryD.Cook2Muchtoooften,abuildingdesignedtocertain insulationvaluestandards(R-value)willnotperform asexpectedafteritisbuilt.Investigationshaveshown themostlikelycauseforthislower-than-expected performanceisduetoimproperamount,selection, and/orinstallationofinsulation.SELECTIONANDINSTALLATIONProperselectionandinstallationofinsulationarevery importantifthetheoreticalR-valueoftheinsulation istobeaccomplished.TestssupervisedbyASTM, Owens-Corning,andtheUniversityofFloridahave shownthatwallsinsulatedwithR-11battsoften performedatonlyR-7orlessbecauseofshoddy installationtechniques. Forexample,anR-11fiberglassbattwillperformat lessthanR-5ifcompressedtohalfthedesigned thickness(31/2inches).Also,ifinsulationisblown orpouredintoanattic,itwillnotperformas expectedunlessitisevenlyrakedtotheproperdepth anddensity. Gapsleftaroundwiring,electricaloutletboxes,piping runs,andnexttoframingmemberscreateheatshort circuitsandconvectivethermaldrafts.Thiscausesa disproportionatedegradationofinsulation performance.Infact,researchhasshownthatgapsin insulationwithinwallcavitiesamountingtoonly3 percentofthetotalareawilldegradetheactual performanceupto20percent. Itisimportanttosealtheopeningswherewiringand pipingrunthroughfloorsandceilingsatthesoleand topplates.Inresidentialconstruction,upto20 percentofinfiltrationheat-lossesoccurbynot attendingtothisproblem.Thereareavarietyof caulkingandfoamproductssuitableforthispurpose. Installationofavaporbarrier,suchasa6mil polyethyleneplasticsheet,betweentheinsulationand thelivingspaceisnotrecommendedonthe conditionedsideofthewallsandceilingsinFlorida homesbecausewatervapormaycondenseinsidethe wallcavity.Ifinsulationsuchasfiberglassbecomes wetfromcondensation,itlosesitseffectiveness. Whenthishappens,mold,mildew,anddamagetothe woodmembersinthewallandceilingmayoccur. Rigidclosed-cellinsulation,suchaspolyisocyanurate andpolystyrenefoamboards,areinherentlyvapor retarders,particularlyiftheyarefoilfaced.These materialsareveryeffectiveasexteriorsheathingin additiontothestructuralrequirements.Astandard 2"x4"studwallwithR-11insulationbattsandfoam sheathingwillprovideabetterinsulationsystemthan 1.ThisdocumentisrevisedFactSheetEES-25,aseriesoftheEnergyExtensionService,FloridaCooperativeExtensionService,InstituteofFood andAgriculturalSciences,UniversityofFlorida.Firstpublished:October1985.Revised:March1995. 2.GaryD.Cook,EnergyExtensionSpecialistandAssistantProfessor,M.E.Rinker,Sr.,SchoolofBuildingandConstruction,Universityof Florida,EnergyExtensionService,InstituteofFoodandAgriculturalSciences,Gainesville. Theuseoftradenamesinthispublicationissolelyforthepurposeofprovidingspecificinformation.Itisnotaguaranteeorwarrantyofthe productsnamed,anddoesnotsignifythattheyareapprovedtotheexclusionofothersofsuitablecomposition. TheFloridaEnergyExtensionServicereceivesfundingfromtheFloridaEnergyOffice,DepartmentofCommunityAffairs,andisoperatedbythe UniversityofFlorida'sInstituteofFoodandAgriculturalSciencesthroughtheCooperativeExtensionService.Theinformationcontainedherein istheproductoftheFloridaEnergyExtensionServiceanddoesnotnecessarilyreflecttheviewoftheFloridaEnergyOffice. TheInstituteofFoodandAgriculturalSciencesisanequalopportunity/affirmativeactionemployerauthorizedtoprovideresearch,educational informationandotherservicesonlytoindividualsandinstitutionsthatfunctionwithoutregardtorace,color,sex,age,handicap,ornational origin.Forinformationonobtainingotherextensionpublications,contactyourcountyCooperativeExtensionServiceoffice.Florida CooperativeExtensionService/InstituteofFoodandAgriculturalSciences/UniversityofFlorida/ChristineTaylorStephens,Dean

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Insulation:SelectionandInstallation Page2theuseofa2"x6"studwallwithR-19insulationbatts alone,asthesheathingservestoinsulatethestuds andanygapsleftinthebattinsulation. Certainconsiderationsshouldbemadeinselecting thetypeofinsulationforaparticularapplication.For example,itisimportantthatinsulationselectedfor wallcavitieswillnotshrinkorsettlewithtime.Inthe past,thereweremanycaseswheretheinitial performanceoftheinsulationwasexcellent,butafter afewyears,performancedeclinedconsiderably becauseofsettlingandmoistureabsorption.New manufacturingstandardshavenowminimizedthese problems.CELLULOSEINSULATION:ABETTER ALTERNATIVEUseofblowndryordampcelluloseisbecomingmore andmorepopularbecauseithasexcellentinsulating ability,costislow,anditismadefromrecycled paper.(CelluloseinsulationhasanR-valuebetween 3.3and3.5perinch,aboutthesameasfiberglassor rockwoolinsulation.)Whencellulosewasfirstused inthe1960sand1970s,itwastreatedwithasulfatebasedchemicaltomakeitfire-resistant.Thissalt absorbedmoisturefromtheairandbecameaweak acid,makingtheinsulationlesseffectiveandcausing ittoslumpandcorrodesurroundingpipesandmetal. Allthishaschanged.Newproductspecifications requiretheuseofboron-basedchemicalstomakethe insulationfire-retardant.Thesechemicalsaremore environmentallybenignandhavetheadditional benefitofrepellingfleas,cockroaches,andmany otherinsects.Celluloseinsulationmayalsoavoid potentialair-qualityproblemslinkedtofiberglassand rockwoolthatisnotencapsulated. Newtechniquesforsprayingcellulosehavemadeitan optionforwallinsulation.Blowingdampcellulose betweenwallcavitiesontheexteriorsheathing providesforcompletecavityfillingincluding aroundwiresandpiping.Theexcesscanbescraped smoothandreused.Thisinsulationshouldbe completelydrybeforesheetrockisinstalledtoprevent futuremildewandmoistureproblems.FIBERGLASSINSULATIONFiberglassinsulationcomesinseveralforms:batts, blown,andboards.Blowninsulationcanbeusedin atticapplications,whilebattscanbeusedinwall cavitiesandtheattic,althoughblowninsulationwill givebettercoverage.Fiberglassboardsareusedin theconstructionofductsandincertainheating,air conditioning,andventilationapplications. Fiberglassshouldbeselectedandusedwithcaution. TheJuly1994issueof EnergyDesignUpdate indicated thatglasswoolwillbelistedas"reasonablyanticipated tobeacarcinogen"inHealthandHumanService's SeventhAnnualReportonCarcinogens (ARC).The useoffiberglassbattsinwallcavitieswillprobably posenorisktooccupantsasitisreasonablyconfined orencapsulatedbytheexteriorandinteriorsheathing. Itshouldnotbeusedasductboardunlessitisfaced withaluminumfoilorothermildew-resistantplastic coatingsonbothsides.Whenfiberglassductboardis unfacedontheinside,itcanposemoisture-related indoorair-qualityproblemsaswellasintroducinga potentialcarcinogenintothehome'sairconditioning system.Iftheductboardbecomeswet,itcanharbor moldandmildew,dustmites,andothercontaminants, aswellasreducetheeffectivenessoftheductboard insulation. Fiberglassisnotrecommendedforuseintheatticas itwillexposethebuildingoccupantsorworkersto fiberglassparticlesifaccesstotheatticisneededfor maintenanceorstorage.RecentresearchbyOak RidgeNationalLaboratoryhasshownthatfiberglass insulationintheatticisnotaseffectiveascellulose insulationbecauseofthecapabilityoffiberglass insulationtosupportconvectiveaircurrents.Ifan existingatticspacehasfiberglassinsulation,either battorblown,itcanbemademoreeffectiveandless riskybyblowingalayerofcelluloseinsulationoverit. Thiswillincreasetheoverallinsulationvalueofthe attic,encapsulatethefiberglassinsulation,andreduce thepossibilityofconvectiveaircurrentsinthe insulationsystem.UREA-FORMALDEHYDEFOAMAfteratwo-yearban,urea-formaldehydefoam insulation(UFFI)isnowallowedforusein residentialapplication.Urea-formaldehydefoams mustbemixedwithgreataccuracy;otherwise,excess shrinkageandharmful,unpleasantfumescanoccur. Onlyabout0.2percentoftheoccupantslivinginthe morethan500,000homeswithUFFIinsulationhave reportedhealth-relatedproblemssuchasheadaches, eyeirritations,andrespiratoryproblems. Ifunacceptablelevelsofformaldehydefumesare determinedtooriginatefromUFFI,contactan

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Insulation:SelectionandInstallation Page3Table1. GenericBuildingInsulationComparison GenericInsulation R/inch lb/ft3 Advantages Disadvantages Battsandblankets Fiberglass 3.2 0.6-1.0 Lowcost,noncombustiblewithout facings,stable Facingsmaybecombustible, bindersmayburn,suspected carcinogen Rockwool 3.6-3.7 1.5-2.5 Lowcost,noncombustiblewithout facings,stable Facingsmaybecombustible, bindersmayburn,suspected carcinogen Boards Cellularglass 2.63 8.5 Highcompressivestrength, noncombustible,impermeableto moisture,stable Highcost,lowRperinch,freezethawdamagepossiblewhenin contactwithwater Mineralfiberwith binder 3.45 15 Providesstructuralsupport,fire resistant,stable Moderatecost,modestRperinch, bindermaybecombustible Polyurethaneand polyisocyanurate foam Unfaced:6.2-5.8; Faced:7.1-7.7 2.0 HighRperinch,mayprovide infiltrationseal,lowmoisture absorption,stable Moderatecost,combustible(polyisocyanuratelesssothan polyurethane),nonstructural Fiberglass 4.25 3.0 GoodRperinch,lowcombustibility, goodacousticalabsorption,stable Highcost,bindersmayburn, suspectedcarcinogen Expanded polystyrenefoam Extruded:5.0; Molded:3.9-4.4 0.8-3.0 GoodRperinch,mayprovide infiltrationseal,lowmoisture absorption,stable Combustible,nonstructural Insulatingconcrete 0.8-2.0 20-40 Noncombustible,canprovide structuralsupport,stable LowRperinch Loosefill Cellulose 3.2-3.7 2.2-3.0 Lowcost,goodRperinch, availability,environmentallyfriendly, repelsinsects Highmoisturepermeabilityand someabsorption,maysettle0-20% ifinstalledattoolowadensity. Fiberglass 2.2 0.6-1.0 Lowcost,noncombustible Airandmoisturepermeability,may settle,suspectedcarcinogen Rockwool 2.9 1.5-2.5 Lowcost,noncombustible Highmoisturepermeability,may settle,suspectedcarcinogen Perliteand Vermiculite 2.5-3.7 2-11 Lowcost,noncombustible,stable Highmoisturepermeability Foaminplace Polyurethane/ polyisocyanurate 5.8-6.2 2 HighRperinch,mayprovide infiltrationseal,lowmoisture absorption Moderatecost,combustible (polyisocyanuratelesssothan polyurethane),maysuffersome shrinkage Ureabasedmixtures 4.2 0.6-0.9 HighRperinch,mayprovide infiltrationseal Moderatecost,combustible; improperlyinstalledfoammayshrink significantlyand/orcauselingering formaldehydevapors Reflectiveinsulation Twolayer R-5 Low-cost,non-combustible,can provideinfiltrationseal,lowthermal mass,veryeffectiveasaradiantheat barrier Dustonreflectivesurfacesmay reduceperformance,bestwhen usedwithconventionalinsulation Threelayer R-7.5 AdaptedfromU.S.Navy'sBuildingMaterialCompilation

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Insulation:SelectionandInstallation Page4insulationcontractorwhomaytakeorrecommend certainstepstominimizethedanger. Table1canassistthebuilderandcontractorin selectingtheproperinsulationforajob.REFERENCESHardenbrook,H., Walker'sInsulationTechniquesand EstimatingHandbook, ed.G.D.Cook.(Chicago: Walker,1983). Nisson,J.D.Ned,ed.,"FiberglasstoBeIncludedin U.S.CarcinogenReport," EnergyDesignUpdate 14(1994):7,1.