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A designer’s guide to specifying warranted austenitic stainless steel fasteners and sealants
CI/SfB Reference by RIBA SfB Agency
Xt6January 2008
email: [email protected]: 0113 2085 578TechnicalFax: 0113 2085 539 1
Contents
Introduction to the SFS Group of companies
Section 1 Introduction 1.1 Performancecriteriaoffastenersandsealants 1.2 Industryassociationsandpartnershipswithleadingsystemsuppliers 1.3 Examplesofrecentinnovations
Section 2 Durability (Corrosion resistance) 2.1 Theproblem 2.2 Fastenermaterials 2.3 Limitationsofcoatedcarbonsteel 2.4 Typesofstainlesssteel 2.5 Carbonorstainless?Specificationselectionconsiderations 2.5aSystemmaterials 2.5bDesignliferequirements 2.5cExternalenvironment 2.5dInternalenvironment/buildinguse 2.5eProject-basedlongtermwarrantyrequirements 2.6 Fastenermaterialselectortable 2.7 SFSintecausteniticstainlesssteelfastenerrange
Section 3 Weathersealing 3.1 Theproblem 3.2 Washerdesign 3.3 Specialistfastenerdesignforweathersealing 3.4 Specialistwarrantedsealants&clampingfastenersforweathersealing
Section 4 The “Part L” issue - Airsealing and thermal bridging 4.1 OverviewofBuildingRegulations-2002&2006-Theproblem 4.2 Eliminationofthermalbridgingbythermallybrokenfasteners 4.3 Achievingairtightnesswithwarrantedsealants&clampingfasteners
Section 5 Aesthetics by design 5.1 Theproblem 5.2 Factory-colouredsolutions 5.2a Mouldedheadsolution 5.2b Unobtrusiveheadsolution 5.2c Obtrusiveheadsolution 5.2d Singlepointglassfixings
Section 6 Technical performance 6.1-6.15 Technicalperformancecriteria
Section 7 Specification design support 7.1 Modelspecifications 7.2 Innovationandquality 7.3 Technicaladvisoryservice 7.4 Training-CPDSeminarsandon-siteSection 8 Case studies
A designer’s guide to the specification of warranted fasteners and sealants
Co
ntents
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Introduction to the SFS Group of companies
TheSFSGroupofcompanies,whichhasitsheadquartersinHeerbrugg,Switzerland,isoneoftheworldsleadingdevelopers,manufacturersandsuppliersofhighprecisioncomponentsforavarietyoftechnicalindustries.
TheSFSGroupdirectlyemploysover3900personnelandin2006turnedover£530million.
Global manufacturingTheGrouphasglobalmanufacturingthroughcentresinSwitzerland,France,USA,Italy,SwedenandUK.
Global sales and marketingProductsaresuppliedintotheglobalmarketthroughSFSsalesandmarketingorganizationsstrategicallylocatedinmanycountries.
UK HeadquartersTheUKheadquarters,whichincludesmanufacture,logistics,andsalesandmarketing,isbasedinLeeds.FastenershavebeenmanufacturedonthisKirkstallRoadsiteforover100yearsandin1997theplantwasredevelopedresultinginafacilityunrivalledintheUKfastenerindustry.FromthissiteSFSintecLtdcanofferarchitects,designers,consultingengineersandcladdingenvelopecontractorsaprovencommitmenttoproductquality,soundtechnicalsolutionsandefficientservice.
Commitment to investment and innovationTheSFSGrouphasaphilosophyofgrowingitsbusinessbyitscommitmenttoreinvestingtoensurestate-of-the-artfacilitiesand,throughitsextensiveresearchanddevelopmentdepartment,tocontinualinnovationofnewproductsandservices.
Industry associations SFSintecisactivelyrepresentedonthetechnicalcommitteesoftheleadingroofingandcladdingassociationswhoseektoencouragebestpracticeandconformancetoallrelevantregulations.
A designer’s guide to the specification of warranted fasteners and sealants
Globalsalesandmarketing
Globalmanufacturing
Section 1 IntroductionThespecificationofthefastener,despitebeingsuchasmallcomponent,iscriticaltotheperformanceoftheroofingandcladdingsystem.Thefastenerworksinclosecombinationwithsealingproducts,thereforethespecificationofthefastenerandsealingproductsneedtobeaddressedattheearlystagesofdetaildesignoftheprojecttoenablethecompletedenvelopetoperformitsrequiredfunctionthroughoutthefulltermofthesystem’sserviceanddesignlife.
1.1 Performance criteriaThisguideaddressestheprincipleperformancecriteriaoffastenersandsealants,namely;
Durability (corrosion resistance)WeathersealingThe “Part L” issues of airsealing and thermal bridgingAestheticsTechnical performance
Eachparticularapplicationwillneedthevariousproductstocomplywithatleastthreeofthesecriteriaandoften,aswithexternallyexposedfasteners,willrequireallfive.Failureoftheproductstosatisfythesecriteriamayleadtotheinevitable,andsometimescatastrophic,failureofthesystemor,attheveryleast,costlyremedialworks,sometimesevenbeforetheprojectcanbehandedovertotheClient.
Thisguidewillgiveyouthekeyinformationneededforyoutospecifyfastenersandassociatedsealstominimizetheriskofsystemfailure.
1.2a Industry associations Theguidancegiveninthisdocumentisgenerallyconsistentwithpublicationslistedbelowfromtheseassociations,aswellasthatgivenwithinBS5427:Part1:1996-thecodeofpracticefortheuseofprofiledsheetforroofandwallcladdingonbuildings.
NFRC -TheNationalFederationofRoofingContractorsAguidetogoodpractice,ThirdEdition1999andsubsequentTechnicalBulletinsMCRMA -TheMetalCladdingandRoofingManufacturersAssociationDesignGuides&TechnicalPapersEPIC-EngineeredPanelsInConstruction
SPRA-TheSinglePlyRoofingAssociationSingleply-CodeofPractice
MMC Alliance-Modernmethodsofconstruction
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A designer’s guide to the specification of warranted fasteners and sealants
Sectio
n 1Intro
ductio
n
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1.2b Partnerships with leading system suppliersSFSintecalsoworkscloselywithmanyoftheUK’sleadingmanufacturersofroofandcladdingmaterialstokeepuptodatewiththeirowndevelopmentsaswellasseekingtodevelopmoreefficientfasteningandsealingsolutionsfortheirsystems.
1.3 Examples of recent innovations
1.3a Development with Corus Building Systems (KalZip)DevelopmentofSDKselfdrillingfastenersforsecuringaluminiumhalterstoreduceinstallationtimeoftheKalZipsystemandensurehalterfastenerscannotbeoverdriveninsiteconditions.
1.3b Development with SarnafilDevelopmentofathermallybrokenfasteningsystemtoeliminatetheeffectofcoldbridgingwithinsulationandmembranefasteners.
1.3c Development with Ward Insulated PanelsDevelopmentofaself-coringfastenertoeliminatetimeconsumingprecoringandbackfillingontheirTopdekpreengineeredinsulatedroofmembranesystem.
A designer’s guide to the specification of warranted fasteners and sealants
Section 2 Durability ( Corrosion resistance )Definition-“likelytolast”,“remainingusefulforlongperiods”,
“resistingwearanddecay”Ref;Oxford Dictionary
2.1 The problemIfthecontractorisallowedtousecarbonsteelfastenersfortheroofingandcladding,corrosionwillresultinanumberofproblems,andifallowedtoprogress,ultimatefailureofthesystemmayoccur.
2.1a Problems due to corrosion of the head and washerStainingofthecladding
Reductioninpulloverperformance
Potentialleakageinto/throughthesystem
Increasedmaintenance&remedialwork
2.1b Problems due to corrosion of the shankReductionintensileperformance
Reductioninshearperformance
Reductioninpulloutvalues
Stainingtointeriorsurfaces
2.1c Problems due to hidden corrosionWhilstcorrosionofexposedheadsontheexternalfaceofthebuildingandcorrosionofthevisibleshankinsidethebuildingarebotheasilyidentified,whatisconsideredamuchgreaterstructuralandsecurityriskisthatofcorrosionwithintheroofingorcladdingsystem.Thiswouldnotbevisibleandwouldonlymanifestitselfuponultimatefailureofthefastener,whichwouldresultinpartial,andpotentiallytotal,detachmentofthesystem.
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A designer’s guide to the specification of warranted fasteners and sealants
Sectio
n 2D
urability
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2.2 Fastener materialsThreadedfastenersforroofingandcladdingsystemsareavailableinthemarketplacemostcommonlyintwomaterials,coatedcarbonsteelandstainlesssteel.
Aluminiumthreadedfastenersarealsoavailable,howevertheirrangeofapplicationisgenerallyrestrictedtosecuringaluminiumprofilestotimbersupportsandlimitedapplicationsofaluminiumtoaluminium.
2.2a Coated carbon steelCarbonsteelrapidlycorrodesonexposuretohumidity.Fastenersinthismaterialaresuppliedwithsomeformofprotectivecoating,typicallymetallicororganic,oracombinationofthetwo.Cadmiumhasinthepastalsobeenusedasaprotectivecoatingbysomefastenermanufacturers.However,thisisacontrolledsubstancethatishazardoustohealthandthereforereputablemanufacturerswhooperaterecognisedQualityandEnvironmentalManagementSystems,aswellasenforcingHealthandSafetyProcedures,nolongerusecadmiumasaprotectivecoatingonthreadedfasteners.
2.2b Stainless steelForincreaseddurability(corrosionresistance),fastenersarealsomanufacturedinvariousgradesofstainlesssteel.
TherelativemeritsofthesegradesarediscussedingreaterdetailinSection2.4
OverthefollowingparagraphsinSection2.3ofthisguidewillbeexplainedthelimitationsofcoatedcarbonsteelandthetypesof“stainless”steelsappropriatetoroofingandcladdingfasteners,andthedifferentaspectsthatshouldbeconsideredinorderthatthechoice,appropriatetotheproject,canbemadebetweencoatedcarbonor“stainless”steel.
A designer’s guide to the specification of warranted fasteners and sealants
2.3 Limitations of coated carbon steel
2.3aUncoatedcarbon steel rapidly corrodesuponexposuretohumidityandpollutedenvironments
Surfacecoatingswithexcellentcorrosionresistancecanbeappliedtoprolongafastener’slifebuttheywillonly slow down the corrosionprocess
Theeffectivenessofthesecoatingscanonlybegaugedafterconsideringtheconditionof the coating once the fastener has been appliedwithintheconstruction
Thesecorrosionresistantsurfacecoatingstendtohavepoor abrasion resistance
2.3b Pitched roofing and cladding systems;Coatingsonfastenerswithinmosttypesofmetalpitchedroofingandcladdingsystemswillinevitablysufferdamage during installationasthemajorportionoftheshankpenetratesthemetalweathersheetandpurlin.
2.3c New flat roof constructionsThereislessriskofcoatingdamagewithinnew“flat”roofingconstructionsasthefastenerisusuallyappliedthroughlessabrasivematerialssuchastheinsulationboardsandweatherproofinglayer(s)-thereforethecoatingsaremoreeffective,however;
2.3d Refurbishment over flat roofsThereisanincreasedriskofcorrosionofcarbonsteelasthecoatingmaybeabradedasitpassesthroughmaterials(chippings)withintheexistingbuild-up.Additionallythereistheprobabilityofincreasedmoisturecontentwithintheexistingbuildupwhichwouldacceleratethecorrosionrate.
2.3 Keynote summaryWill coated carbon steel satisfy all your requirements?
Coating damage reduces fastener life
Corrosion leads to reduced technical performance
Corrosion leads to potential water ingress
Corrosion reduces aesthetic value
Coated carbon steel may be adequate for some less onerous applications - however consider possible change in use during building lifespan
Corrosion of carbon steel fasteners may lead to high consequential damage costs, disruption costs and expensive remedial costs
Fasteners must have at least an equal life to the proposed roof system
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A designer’s guide to the specification of warranted fasteners and sealants
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A designer’s guide to the specification of warranted fasteners and sealants
2.4 Other types of “stainless” fasteners.Becauseofthehightechnologicalinvestmentrequiredforthemanufactureofbi-metallicausteniticstainlessselfdrillingfasteners,alternativematerialsandmethodsofhardeninghavebeenintroducedbysomedistributorsclaimingaperformancecomparabletobi-metalausteniticgrades.Independenttestshavehighlightedfundamentalweaknesseswiththesealternativestainlessproducts.
2.4a Nitrided stainless fastenersThereisaprocessavailablewhichhardensstainlesssteelthreadedwire,includingausteniticgrades,sufficientlytoenablethemtoself-drillmildsteelwithouttheneedtoincorporatethehardenedcarbonsteeldrillpoint(bi-metallic)element.
However,theprocessusedresultsinchromiumbeingwithdrawnfromthesurfaceofthestainlesswirewhichreducesitscorrosionresistance.Thismethodisreferredtoasnitriding.
Toreinstatecorrosionprotection,thefastenersmaythenbecoatedwith,typically,azinc/organiccoating….similartothecoatingappliedtocarbonsteelfasteners.
Itisthiscoatingthatprovidesthecorrosionprotectionand,asdescribedinSection2.1&2.3,thecoatingwillbeinevitablydamagedduringinstallation,whichwouldacceleratethecorrosionrateandthusprovideonlytemporarycorrosionprotection.
2.4b Modified martensitic stainless fastenersWhilstmartensiticgradesofstainlesssteelfastenerswithonly11%chromiumareknowntohavepoorcorrosionresistance,someaspectsoftheircorrosionperformancemaybeimprovedbymodificationofthematerialinvolvingchangingtheelementmixoftheirformulationandapplyingcertainmanufacturingtechniques.
Onesuchmanufacturingtechniqueinvolvesutilizingawirewithanextremelyhardsurface(>550HV)whichenablesthemtoselfdrillmildsteelwithouttheneedtoincorporatethehardenedcarbonsteeldrillpoint(bi-metallic)element.SuppliersclaimthismaterialoffershigherresistancetocorrosionwhensubjectedtoacceleratedKesternichandSaltspraytests-thisissubjecttothethreadformingqualityachievedwhichhasbeenshowntobevariable.
Hydrogen and stress corrosion brittleness
However,real-lifeexposuretestsinanumberofenvironmentalconditionshaveshownthistypeoffastenermaterialtobesubjecttohydrogenandchlorideinducedstresscorrosionandbrittleness-thiswouldn’thavebeenevidentunderKesternichandSaltspraytesting.Thistypeofbrittlecorrosionisinherentinthehardmaterialandisnotnecessarilyvisibletothenakedeye.
AsaresultofextensiveresearchworkcarriedoutbycorrosionexpertsinGermany,SwedenandtheUKonthistypeofmaterial,SFSintechavebeenadvisedthattherisksassociatedwithmodifiedmartensiticfastenersforroofingandcladdingaresignificantandthereforewecontinuetocomplywithindustryguidelinesandStandardsbymanufacturingstainlesssteelselfdrillersfromausteniticgradeswithabi-metallichardeneddrillpoint.
2.4 Keynote summaryAustenitic stainless steel fasteners, such as grades 304 and 316, have been proven over a period exceeding 40years in environmental conditions worldwide. Austenitic grades are the only type recommended within BS5427:Part :1996.
To enable selfdrilling through mild steel (of up to 14mm thickness), fasteners in these grades are manufactured with a bi-metallic hardened carbon steel drillpoint.
A designer’s guide to the specification of warranted fasteners and sealants
Corrosionofnitridedstainless
Non-chromesurfacelayeronnitridedstainless
Brittlefailureofmodifedmartensiticstainless
Stesscracksinmodifedmartensiticstainless
2.4 Types of stainless steel“Rusting”isregardedbymanyasaprocesswhichisnotapplicabletostainlesssteel-thisishoweverincorrect.“Stainless”steelisagenerictermcoveringover200differenttypesofalloywhichall,tovaryingdegrees,stain-lessthancarbonsteel.Stainlesssteelscanbeclassifiedintothreemaingroups;
Austenitic, Ferritic and Martensitic.
2.4a Austenitic stainless steelOnlygradesconformingtoBS5427:1996(seenote1)Containsatleast17%chromiumContainsatleast8%nickelMolybdenummaybeaddedforenhancedcorrosionresistanceNon-hardenable(seenote2)Non-magnetic(seenote3)Lowthermalconductivity;25%ofcarbonandmartensiticstainlesssteelBestknowngradesare304and316
Excellentcorrosionresistance(seenote4)
These characteristics make austenitic stainless steels the only suitable type for selfdrilling/threadforming fasteners for roofing and cladding.
2.4b FerriticContainsatleast12%chromiumLowerductilitythanmartensiticsandausteniticsCannotbehardenedSusceptibletobrittleness
These characteristics make ferritic stainless steels unsuitable for the manufacture of selfdrilling/threadforming fasteners for roofing and cladding.
2.4c MartensiticContainstheminimumchromiumcontentof11%PoorcorrosionresistanceSusceptibletostresscorrosionCanbehardened(attheexpenseoffurtherstresscorrosionrisk)Highthermalconductivity(similartocarbonsteel)MagneticModifiedformsavailablebutstresscorrosionconsideredtoogreatarisk
(see2.4bonpage11)
These characteristics make martensitic stainless steels unsuitable for self drilling/threadforming fasteners for roofing and cladding.
Note 1-Clause2.8.3fromBS5427:Part1:1996-Codeofpracticefor:Theuseofprofiledsheetforroofandwallcladdingonbuildings.Part1:Design.Note 2-Thethreadrollingprocesshardensthethreadssufficientlytothreadformbutnotenoughforselfdrillingintomildsteelsupportsegpurlinsandrails.Therearespecialtechniqueswhichincorporateaheattreated(hardened)carbondrillpointtobejoinedtoanausteniticstainlessfastenertoallowselfdrilling.Thesemaybereferredtoasbi-metalfasteners.Itisvitalthat,onceinstalled,allthreadswithinandabovethesupportareausteniticstainless.Note 3-Extremecoldformingofausteniticstainlesssteelwirecanimpartasmalldegreeofresidualmagnetismwithoutadverselyaffectingthematerialsproperties.Note 4-Itisacknowledgedwithinindustrydocumentationthatcertaingradesofstainlesssteel,includingsomeausteniticgrades,maybeatriskofchlorine-inducedstresscorrosioninconditionswhichmayoccurforexample,inswimmingpoolhalls.Poolhalldesign,plannedoperatingandmaintenanceconditionsmustbecarefullyconsideredbywatertreatmentexperts,aswellasarchitectsanddesigners,tominimiseanyrisk.Gradesofstainlesssteelwhichmaybesusceptibletochlorine-inducedstresscorrosionshouldbelimitedtothosecomponentsusedin“nonsafety-critical”applications,i.e.inthoseconditionswhichwouldnotresultinpersonalrisk/injuryintheeventoffailure.Thereisnohistoryoffailureofthreadformingroofingandcladdingfastenersoverswimmingpoolsandwewouldnotconsidersuchfastenersforsecuringoverpurlin/railmetalcladdingsystemsas“safety-critical”.Austeniticstainlessfasteners,typically304,offerthedesignerappropriateandreadilyavailablesolutionswithproveninsignificantrisk.
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2.5 Coated carbon or austenitic stainless steel? Selection considerations:Inorderthatadesignerorspecifiercanmaketheappropriateselectionbetweencoatedcarbonsteelorausteniticstainlesssteel,thefollowingconsiderationsshouldbeaddressed;
2.5a System materials2.5b Design life requirements2.5c External environment2.5d Internal environment / building use2.5e Project-based long term warranty requirements
All these should be considered in the overall risk assessment.
TheseconsiderationshavebeentabulatedunderSection2.6toassistinfastenermaterialselection.
A designer’s guide to the specification of warranted fasteners and sealants
2.5a System materials
2.5a i) Pitched roofing and cladding systemsCompatibilitywiththesheet/systemmaterialaswellasthepurlin/railwillinfluencethechoicebetweencoatedcarbonsteelorausteniticstainlesssteelfasteners.
Typicalmaterialsforthesystemandsupportmayinclude;
StainlesssteelCoatedmildsteelAluminiumFibrecementCementitiousboardsHighpressurelaminates“Plastics”-GRP,polycarbonatesandPVCTimber
2.5a ii) Flat roofing systemsItisgenerallythecompatibilityofthedeckthathasadirectinfluenceonthechoicebetweencoatedcarbonsteelorausteniticstainlesssteelfasteners.
Decktypesinclude;Coated(galvanized)steelAluminiumTimber“Concrete”
2.5a iii) Cautionary notes;Refurbishment over existing roof coverings -generallyflatroofing.Theinsulationtypewithinflatroofingdoesn’tgenerallyinfluencethefastenermaterial,however,onrefurbishment,wheretheexistinginsulationandweatherproofingistoremain,itistheconditionratherthantypeoftheexistingbuildupwhichwillinfluencethefastenermaterialchoice.Ifthereisdampnesswithintheexistingbuildupitwouldbeprudenttouseausteniticstainlessfasteners.
Timber preservatives;Timbercomponentsusedwithinconstructionareoftentreatedwithpreservatives.GuidanceontimberpreservationisincludedwithinBS4072:Part2:1987andBS5268:Part5:1989.GenerallytreatmentsfallintoeithertheOSorCCAtype(organicsolventsorcopper/chromium/arsenic).OStypetreatmentsarenotconsideredtohaveanycorrosiveeffectoncoatedcarbonsteelfasteners,however,ifthetimberislikelytobecomewet,corrosionwouldbeexpected.ThepresenceofCCApreservativesintheseconditionswillincreasetheriskofcorrosion.“Ifthetimberislikelytobecomewetandalongservicelifeisrequired,usefittingsofausteniticstainlesssteel…inpreferencetoothertypese.g.carbonsteel”.
2.5a Keynote summaryIt is industry practice to use austenitic stainless steel fasteners in combination with aluminium and stainless sheet/system materials. Coated carbon steel fasteners could be considered with all other system materials depending on their suitability relative to the following Selection considerations under 2.5 b) - e).
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A designer’s guide to the specification of warranted fasteners and sealants
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2.5b Design life requirementsTheclient,orhisagent,shouldspecifytheintendeddesignlifeoftheproposedbuildingandindividualproducts,componentsorassemblies.
BS7543:1992 Guide to: Durability of buildings and building elements, products and components
GuidanceisgiveninTables1and2belowandourinterpretationwithregardsfastenermaterialselectionisreproducedopposite.
Table 1 - Categories for design life for buildings
Note 1:Specificperiodsmaybedeterminedforparticularbuildingsinanyofcategories2to5providedtheydonotexceedtheperiodsuggestedforthenextcategorybelowonthetable;forexamplemanyretailandwarehousebuildingsaredesignedtohaveaservicelifeof20years.Note 2:Buldingsmayincludereplaceableandmaintainablecomponents-seeTable2below
It is clearly evident that many of the buildings where fasteners and cladding envelope sealants are used within the roofing and cladding construction are going to be, at the least, in Category 3, Medium Life, 30 years minimum.
Table 2 - Categories of design life for components or assemblies
DependinguponthedesignlifeforthecompletebuildingasselectedfromTable1,thecomponentsandsystems,forexampletheroofingandcladdingenvelope,arethenselectedbutalsohavetobecategorizedfromTable2aseitherreplaceable,maintainableorlifelong.
ExtractsfromBS7543:1992arereproducedwiththepermissionoftheBSI.CompleteeditionsofthestandardscanbeobtainedfromBSICustomerServices,389ChiswickHighRoad,LondonW44AL
A designer’s guide to the specification of warranted fasteners and sealants
Category Description Building life
of Category
Examples
1. Temporary Agreedperiod
upto10years
NonPermanentsitehutsandtemporaryexhibitionbuildings
2. ShortLife Minimumperiod
10years
Temporaryclassrooms;buildingsforshortlifeindustrialprocesses,office
internalrefurbishment;retailandwarehousebuildings
3. Mediumlife Minimumperiod
30years
Mostindustrialbuildings;housingrefurbishment
4. NormalLife Minimumperiod
60years
Newhealthandeducationalbuildings;newhousingandhighquality
refurbishmentofpublicbuildings
5. LongLife Minimumperiod
120years
Civicandotherhighqualitybuildings
Category Description Life Typical examples
1. Replaceable Shorterlifethanthebuildinglifeand
repacementcanbeenvisagedatdesignstage
Mostfloorfinishingsandserviceinstallation
components
2. Maintainable Willlast,withperiodictreatment,forthelifeof
thebuilding
Mostexternalcladdings,doorsandwindows
3. Lifelong Willlastforthelifeofthebuilding Foundationsandmainstructuralelements
2.5b Design life requirementsAshasbeennotedfromtheTable1onthepreviouspage,thedesignlifeforthemajorityofindustrial,commercialandpublicsectorbuildings,aswellasotherspecialistusebuildings,willfallwithintheMediumLifecategoryofaminimum30years.Table2thengivesthedesignlifeforthecomponentsorassembliesusedwithintheconstruction.
Fasteners and sealant design life relative to Table 2:
2.5b i) Question: Can fasteners and cladding envelope sealants be classed as “Replaceable” ?Non-exposedfastenersandsealingproducts,bothweatherandairseals,canoftenonlybeaccessedbyremovaloftheexternalweatheringsheet.Insomecasesremovaloftheweatheringsheetinordertoaccessconcealedfasteners,withinitsrequireddesignlife,maynecessitatethatitbetotallyrenewed.Iffastenersandsealsweretodegradewithinthedesignlifeofthesystem,theninstallingnewfasteners,bothexposedandnon-exposed,intotheirexistinglocationwouldoftenresultingreatlyreducedpulloutvaluesandthereforepresentastructuralrisk(unlessapurpose-designed“repair”fastenerwereused).Asafurtherexample,insulatedpanelfastenershaveenlargedthreadsundertheheadto“support”theouterskinandmaintainaweatherseal(section3.3a).Ifthefastenerprematurelycorrodes,thentheresultingleakagemaydamagethesheetaroundtheholesuchthatsimplyinstallinganewfastenermaynotprovidetherequiredlevelsofsheetsupport.
Answer-FastenersandsealingproductsarenotclassedasReplaceable
2.5b ii) Question: Can fasteners and cladding envelope sealants be classed as “Maintainable” ?Asnotedabove,non-exposedfastenersandsealscanonlybeaccessedbyremovaloftheexternalweatheringsheet.Exposedfastenersmay,intheory,havetheirvisibleparts“recoated”butthisshouldnotberegardedasacceptableatthedesignstageofaproject.Furthermore,applyinganewcorrosionprotectivecoatingtothevisiblehead,providinganappropriatepretreatmentcanbecarriedout,aswellasbeing,inmostcases,aestheticallyunacceptable,wouldnotreinstatecorrosionprotectiontotheconcealedshankwhichmayalsobesufferingfromcorrosion.
Answer-FastenersandsealingproductsarenotclassedasMaintainable
2.5b Keynote summaryFasteners and cladding envelope sealants are not Replaceable or Maintainable. They therefore have to be designed and selected to be Lifelong. ie they must have a design life at least equal to that of the roofing and cladding system within which they are used.
Coated carbon steel fastenerscouldbeconsideredforonlyTemporaryandShortLifebuildingsandlimitedbuildingtypesintheMediumLifecategory.Austenitic stainless steel fastenersshouldbeconsideredasthepreferredchoiceforMediumLifecategoriesandtheonlyappropriatechoiceforNormalandLongLifecategories
Weather and air sealing product specificationsshouldalsobecompatiblewiththedesignlifeofthesystemanditsfasteners.
A designer’s guide to the specification of warranted fasteners and sealants
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2.5d Internal environment / building useSomebuildinguses,andtheprocessestheyhouse,canpresentveryonerousinternalenvironmentalconditionsuponthefastenersandseals.Insuchcases,coatedcarbonsteelwouldnotbeconsideredanappropriatefastenermaterialchoice.
2.5d i) Building use - “At risk” categories;Duetotheirgeneralfunctionandinternalconditions,austeniticstainlesssteelfastenersshouldbeconsideredonthefollowingbuildingcategories
Leisureindustry…Swimmingpools,sportscentres,stadia.
Schools
Hospitals
Transportindustry…Airportterminalsandbuildings,ferryanddocklandfacilities,railwaybuildings
Waterindustry…sewageandwatertreatmentworks,pumpingstations
Powerstations
Manufacturing…Paper,pharmaceuticals,chemicals,brick&masonryproducts,breweries,textiles,food&drink
2.5d ii) Building use - further “At risk” categories;Additionally,therearesomeotherbuildingcategorieswhich,eventhoughtheirinternalenvironmentmaybenon-aggressive,demandthatausteniticstainlessfastenersbeconsidered.Thepotentialforleakageresultingfromcorrosionofcoatedcarbonsteelmayresultindamagetoexpensive/sensitiveequipmentandcouldalsobeextremelydisruptivetotherunningofthebusiness.
Hygiene,Foodprocessing
Electronics,computerequipment
Highvaluegoods
2.5d iii) Building use - lower risk categoriesTypicalbuildinguseswherecoatedcarbonsteelfastenershavebeenshowntoperformadequatelyforperiodsoffunctionallifeexpectancyupto25yearsandthereforewherecoatedcarbonsteelcouldbeconsideredinclude;
Retail
Distribution
Manufacturingof“dry”goodssuchasassemblylines,windowsanddoors,automotiveproducts,whitegoodsetc.
2.5d Keynote summaryFrom the above it can be seen that the internal environment / building use has a major influence on the choice of fastener material and that austenitic stainless steel should, in most instances, be specified. Specifying austenitic stainless would also eliminate any future risk if the building use changes.
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A designer’s guide to the specification of warranted fasteners and sealants
2.5c External environmentTheUKsclimateisclassedaswarmtemperatewithraininallfourseasons.BuildingsintheUKarethereforesubjectedtoawiderangeofexternalenvironmentalconditionswhich,initself,presentsonerousconditionsforroofingandcladdingsystemsintermsofresistancetowind,wateringress,UVandcorrosion.
Inadditiontotheclimaticconditionspresentduringeachseason,thelocalatmosphericconditionsintheimmediatevicinityofthebuildingarecriticalintheselectionofcoatedcarbonorausteniticstainlesssteelfasteners.
Typical atmospheres may be divided as in the following table;
Marine Upto2kmfromthesea.Highlevelsofchlorides
Coastal Between2kmand10kmfromthesea
Industrial Atmosphereheavilypollutedbysulphurdioxideandother pollutants,typicallynitricoxides,chlorine,hydrogenchloride, formicacid,aceticacid,allinthevicinityofcorresponding industrialplants.
Urban Denselypopulatedandpollutedbysulphurdioxide
Rural Smallertownsandvillagesgenerallyfreefromatmospheric pollutionconducivetocorrosion.
Note;Veryoftenthesedifferenttypesofatmosphereoverlap,thuspresentinganevenmoreaggressiveexternalenvironmentforboththecladdingsystemanditsfasteners.Forexample,therearemanymarineandcoastalareaswhichareheavilyindustrialised.
2.5c Keynote summaryThe corrosion rate of coated carbon steel fasteners is difficult to predict, however it can be stated with a degree of certainty that;
Coated carbon steel fastenerswouldcorrodewhenexposedtoanyoftheseexternalenvironmentsandthecorrosionratewillincreaseasyoumoveupthetable.
Austenitic stainless steel fastenersaredurableinalltheseexternalenvironmentsandshouldbespecifiedinmarineandcoastalenvironmentsand,inmanycases,wouldberecommendedinindustrialatmospheres.
Cladding envelope sealing productsspecificationsshouldalsobecompatiblewiththedesignlifeofthesystemanditsfasteners.
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A designer’s guide to the specification of warranted fasteners and sealants
Marine
Rural
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2.5e Project-based long term warranty requirementsThereisanincreasingdemandbyclientsandbuildingownersfortheperformanceofproductswithinthebuildingconstructionandenvelopetobewarranted.Theroofingandcladdingindustryhasrespondedtothesedemandsandvariouswarrantyschemesarenowavailable.
2.5e i) Industry Association system based;Warrantiesareavailablethroughanumberofindustryassociations-somewarrantworkmanshipaswellasmaterials.Usuallyaninsurancepremiumisrequiredtobepaidwhichisapercentageoftheenvelopecontractvalue.
2.5e ii) System suppliers warranty schemes;Theprinciplesystemsuppliermayoperatewarrantyschemesforthecompletesystem.Sotheycaneliminatetheriskofsystemfailureduetoancillaryproducts,theprinciplesystemsupplierwillspecifycomponentstobeusedinconjunctionwiththeirproductstomakeupatotalsystem.Warrantiesarethenobtainedfromtheirpartnersuppliersandinstallersandasingletotalsystemproject-specificwarrantyisthenpassedtotheclient.
Systemsupplierwarrantyschemesdonotnecessarilyrequireapolicypremiumtobepaidbytheclient.
SFSintecworkscloselywiththeleadingsystemsupplierswhospecifyfastenersandancillaryproductssuchassealantsappropriatetothewarrantyperiodrequired.
2.5e iii) Component suppliers warranties;Asanalternativetothewarrantyschemesabove,theclient(throughhisarchitect/designer)maywishtospecifyandobtainseparateindividualproductwarrantiesfromallthevarioussupplierswhosecomponentsareusedorspecifiedwithinthesystem,andalsotheinstallerifworkmanshipistobewarranted.
2.5e Keynote summaryProject-specific warranty;Clientsshouldbeencouragedtoobtainwarrantieswhichareproject-specific,andoftenupto30years-andtheseshouldincludeallcomponentscriticaltothebuildingenvelope.Onlyausteniticstainlessfastenerswouldbedeemedtoprovidetherequiredlevelofperformance.
Beware,warrantiesshouldnotbelimitedtosimplysupplyingmoreproducts-theclientshouldseekthere-assurancethatthewarrantycovers“making good the roof”.Theclientshouldensurethesuppliertakesfullresponsibilitywithinthewarrantyoffered.
Products Liability Insurance;ThechoiceofsuppliershouldalsobelimitedbywhethertheirproductionplantsoperateQualityandEnvironmentalManagementSystemsandhavecertificationshowingconformanceto,forexample,ISO9001:2000andISO14001:1996.
A designer’s guide to the specification of warranted fasteners and sealants
2.6 Fastener material selector table Thesections2.1to2.5ofthisguidehavedrawntotheattentionofthedesignerandspecifiertheproblemsrelatingtofastenerDURABILITYandexplainedthedetailedconsiderationsthatmustbemadeinorderthatthecorrectfastenermaterialcanbespecified.Thetablebelowhasbeendesignedtoassistthespecifierintheselectionofthemostappropriatefastenermaterialforeachindividualproject.
Table showing guide to selection of exposed fastener material
Note 1 -Sheet/deckmaterial
Thistablegivesguidanceonthefunctional life expectancyoftheexposedfastenerinvarioussheetmaterials.Consultwiththesheetmanufacturerregardingthemostappropriatesheetmaterialandcoatingsystemanditsfunctionallifeintheparticularenvironment.
Note 2-Non-exposedfasteners
Forcarbonsteelfastenerswhicharenon-exposedtotheexternalenvironmentthefunctionallifewouldbesimilartothosetabledaboveforcarbonsteelwithintegralcolourhead.
Note 3-Warranty
TheperiodsshownintheTableareforfunctional life expectancy.Asitisdifficulttopredictapreciselifeexpectancyofcarbonsteel,itwouldbeprudenttousetheminimumperiodsfordesignpurposes.
Whereafastenerwarrantyisrequired,SFSinteccanwarrantcarbonsteelupto10yearsandausteniticstainlesssteelupto30years.PleaserefertoSection2.5eonpage18forwarrantyoptionsandconsultSFSintecforyourProject-SpecificWarranty.
A designer’s guide to the specification of warranted fasteners and sealants
Fastener material
Environment Functional life expectancy of fastener
Max Sheet/deck material ( see note 1 )warrantyof fastener
Internal External Aluminium Coated steel Stainlesssteel
GRP/PVC fibrecement
Coated carbon steel & push-on cap
Dry/LowHumidity
Urban/rural 10/20 10 0 ✔ 0 ✔
Industrial 10/15 10 0 c 0 c
Coastal/Marine - - 0 ✘ 0 ✘
HighHumidity
Urban/rural 10/15 10 0 c 0 c
Industrial 10 10 0 c 0 c
Coastal/Marine - - 0 ✘ 0 ✘
Coated carbon steel with integral colour head
Dry/LowHumidity
Urban/rural 15/25 10 0 ✔ 0 ✔
Industrial 15/20 10 0 c 0 c
Coastal/Marine - - 0 ✘ 0 ✘
HighHumidity
Urban/rural 10/15 10 0 c 0 c
Industrial 10 10 0 c 0 c
Coastal/Marine - - 0 ✘ 0 ✘
Austentitic stainless steel
AllConditions
Urban/rural 30+ 30 ✔ ✔ ✔ ✔
Industrial 30+ 30 ✔ ✔ ✔ ✔
Coastal/Marine 30+ 30 ✔ ✔ ✔ ✔
Key Recommended✔ NotRecommended✘ Unsuitable0 Checkwithmanufacturerregardingsuitabilityc
XLInsurancecertificate
SFS
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CorusPanelsandProfilesLtd
KingspanLtd
email: [email protected]: 0113 2085 578TechnicalFax: 0113 2085 539 19
APPLICATION DESCRIPTION CODE FASTENER
APPLICATION DESCRIPTION CODE FASTENER
SX3/10-L12-S16*-5.5 x 28S19 washer to roof
S19 washer to roof
SX14/12-L12-S16*-5.5 x 40
SXL2-L12-A14-5.5 x 22
SXCP5-S19*-5.5 x Length
SXCP14-S19*-5.5 x Length
SLP2-S-A14-4.8 x 20
SDK2-S-377-6.0 x 35/45
SDK3-S-377-6.0 x 35/45
SX2/18-A166.3 x 35/45
TDC-S-S16-6.3 x Length
TDB-S-S16-6.3 x Length
SX3/10-D12-5.5 x 28
SX3/10-S16*-5.5 x 28
SX14/12-S16*-5.5 x 40
SL2-S-S14-4.8 x 22
TI-S-6.3 x Length
Telescope TH-75 x Length Fastener IT2-S-C-4,8xLengthTelescope TH-42 x Length Fastener IT2-S-C-4,8xLength
GA-AS-S16-6.5 x45 C
GAZ-811-Ø 22 x 32mm
41AL-PUNKT-30-8Metric Screw M8x45Wood Screw 8x60
41AL-SENK-30-6CountersunkBolt M6x40Wood screw 6x60
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A designer’s guide to the specification of warranted fasteners and sealants A designer’s guide to the specification of warranted fasteners and sealants
Drillerforcoldrolledsteelwithirius®head,colouredwherevisible.
Drillerforhotrolledsteelwithirius®head.
Drillerforclamping/stitchingwithirius®head,colouredwherevisible.
DrillerforinsulatedpanelstocoldrolledsteelwithcolouredSelamouldedhead.
DrillerforinsulatedpanelstohotrolledsteelwithcolouredSelamouldedhead.
Drillerforclamping/stitchingwithcolouredSelamouldedhead.
Drillerforsecuringstandingseamsystemhalterstodeckswithspecialdrivesystemtoeliminateovertorque.
Drillerforsecuringstandingseamsystemhalterstocoldrolledpurlins/tophatswithspecialdrivesystemtoeliminateovertorque.
Drillerforsecuringstandingseamsystemhalterstocoldrolledpurlins/tophatswithhexagonalhead.
Tapperforcoldrolledsteelwithhexagonalhead.
Tapperforhotrolledsteelwithhexagonalhead.
Drillerforsecuringstandingseamsystemclipstocoldrolledpurlins/spacerswithlowprofilehead.
Drillerforsecuringmetaldeckingtocoldrolledpurlinswithhexagonalhead.
Drillerforsecuringmetaldeckingtohotrolledpurlinswithhexagonalhead.
Drillerforclamping/stitchingdecksidelapswithhexagonalhead.
Thermallybrokenfasteningsystemforinsulationtometaldeck,comprisingofafastenerinstalledthroughapolyamide“telescopetube”
Thermallybrokenfasteningsystemforinseamfasteningofsingleplymembranesthroughinsulationtometaldeck,comprisingofafastenerinstalledthroughapolyamide“telescopetube”
Tapperforattachmentofbracketsandsupportstoconcrete.
TapperforsecuringHPLpanelstosteel,aluminiumandtimbersubstrateswithmalethreadonheadtotaketheGAZDesignerRangebelow.
Powdercoatedaluminiumormillfinish304gradeausteniticstainlessDesignerHeads.
304gradestainlesssteeloraluminiumsinglepointraisedheadglassfixings.
304gradestainlesssteeloraluminiumsinglepointflushheadglassfixings.12
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Single ply membrane over insulationon metal deck.
Rainscreen systems.
Single point glass fixings - raised head.
Single point glass fixings - flush head.
Site assembled liner panel systems.
Insulated panel systems.
Aluminium standing seam systems.
Clip fix systems.
2.7 SFS intec austenitic stainless steel fastener range Having explained in Section 2 the durability benefits associated with austenitic stainless fasteners, designers can be reassured that austenitic stainless fasteners for virtually all roofing and cladding applications are available in the marketplace.
Thetablesinthissectiongivesexamplesoffastenersavailablerelativetothevarietyofroofingandcladdingsystems.Unlessnotedotherwise,allfastenersshownaremanufacturedfrom300seriesausteniticstainlesssteel.TherearemanyothertypesavailableandSFSintecwillbepleasedtogiveadviceonspecificapplicationsonthecontactdetailsbelowore-mailingdetails/[email protected]
SFSintechas,inconsultationwithaleadingsealantmanufacturer,developedarangeofweatherandairsealantsdesignedexclusivelytoaspecificationwhichenablesthemtobewarrantedforperiodsupto30yearsandthuscompatiblewiththeSFSintecausteniticstainlesssteelfastenersshownabove.ThesizesofthestripsealantsareasrecommendedbyleadingsystemsuppliersandeitherSFSintecortheappropriatesystemmanufacturercouldbeconsultedforthepositioningandsizeofthestripsealantsspecifictothechosensystem.TherangeissupportedbytestdataconductedinaccordancewiththeNFRCTechnicalBulletin36andisclassedasacross-linkedbutylTypeA+andiscolouredpinkforeaseofidentification.FurtherinformationwithregardsweatherandairsealingisgiveninSections3.4&4.3ofthisguide.
6mmx5mmSFSsealTypeA+pinkstrip
4mmbeadSFSsealTypeA+pinkstrip
6mmbeadSFSsealTypeA+pinkstrip8mmbeadSFSsealTypeA+pinkstrip
18mmx4mmUSFSsealTypeA+pinkstrip
22mmx5mmUSFSsealTypeA+pinkstrip
50mmx1mmSFSPolybandTypeA+pinkstripType A+ sealants for metal roofing
and cladding
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Section 3 Weathersealing
3.1a Poor washer designExposedfastenersi.e.thosewhichpenetratetheexternalweatheringsheet,havetosealthepenetrationinthesheetforthedesignlifeoftheroofingandcladdingsystem.Exposedfastenersarethereforesuppliedwithasealingwasher.Thedesignofthewasher,andinsomeapplicationsthedesignofthefasteneritselfatthesheetinterface,isthereforecriticaltoensurelongtermperformancecompatiblewiththerestofthesystem.
The total sealing washer design must therefore be resistant to the following;
Environmental conditions;General weathering
Water ingress
Acid rain
Ultra-violet rays
Ageing
Mechanical loadings;Pullover (wind suction)
Abrasion
Splitting
Vibration
Movement (wind/thermal) of sheet
Site applications;Overdriving
Oblique/Non-perpendicular driving
3.1b Poor sealant designEndlapsandsidelapsonprofiledexternalroofsheets,aswellastheexternalflashingsatalljunctions,needtobeeffectivelysealedtoprovidecontinuityoftheweathertightenvelope
Thesesealantshavetowithstandmanyoftheenvironmentalconditionsandmechanicalloadingsasnotedaboveforthefasteners.Manyofthesealantsuppliersarenotpreparedtogivemeaningfulwarrantiesontheirstandardsealantranges,suchthattheycouldbecompatiblewithafastenerorsystemwarrantyof30yearsasreferredtounderSection2.5ofthisguide.
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3.2 The sealing washer solution.Long-term securitySFSintechasconsideredallthevariousperformancerequirementsofthesealingwasher,inconjunctionwiththefastenerdesignrelativetotheparticulartypeofroofingsystem,andhasengineeredweathersealingdesignstoprovidelong-termsecuritycompatiblewiththefastenerandthematerial/systembeingfastened.
3.2a EPDM sealing elementSealingwashersshouldbespecifiedwithanEPDMelastomer(EthylenePropyleneDieneMonomer)asthesealingelement.Anelastomerisamaterialwhichcanberepeatedlystretched(andcompressed)toatleasttwiceitsoriginallengthandwillthenreturntoitsoriginallengthimmediatelytheloadisreleased.Duetoitsoverallperformance,EPDMisanestablishedmaterialwithinthefastenerandbuildingindustriesand,inmostinstances,hasreplacedneoprenewhoselimitationsincludereducedresistancetogeneralweathering,ultra-violetradiation,waterandtemperature,aswellasageing.
ThethicknessandhardnessoftheEPDMshouldbedesignedrelativetothefastenertypeandwasherdiameter,forexamplewherasthenormalhardnessis70/80shore,onclampingandinsulatedpanelfastenersamuchsofterEPDMof40shoreisused,referto3.3a&b.
3.2b Metal backingToensuretheEPDMcompressesevenlyandformsasealagainstboththesheetandthefastenershank,theEPDMshouldbevulcanizedtoametalbackingwasher.Merelyglueing,asisthepracticeofsomemanufacturers,wouldpresentariskoftheEPDMdelaminating.Theproblemwithloosesealingelementsisclearlyillustratedonthepreviouspagewhere,foranumberofreasonsassociatedwithpoorfastenerdesign,thesealingelementhas“extruded”beyondtheheadofthefastenerandhasbeendestroyedwiththeresultthatthesealwillnolongerbeeffective.
3.2c DiametersSealingwashersareavailableinawiderangeofdiametersfrom,typically,12mmto32mm.
Forprimaryvalleyfixingofthrough-fixedmetalroofweathersheetsandinsulatedroofpanels,19mmisusuallythepreferreddiameter.
For“plastics”rooflightprofiles-typicallyGRPandpolycarbonate,largerdiameterwashers,typically32mm,orinsomeinstancescrownsaddlewashers,arerecommended.
Forwallingsystemsandsecondary(clamping)fasteners,smallerdiameters,typically12mm-16mm,areused.
A designer’s guide to the specification of warranted fasteners and sealants
19mm&32mm
12mm&16mm
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3.3 Specialist fastener designs to ensure weathersealing3.3a Insulated panel fastenersThe problemFactoryformedinsulatedpanels,andalsosite-assembled,bytheirverynature,havea“non-rigid”section(theinsulationcore)betweentheexternalskinandthesupportingpurlin.Notallinsulatedpanelfastenersareadequatelydesignedfortheapplicationandthereforefailtoprovidethelong-termcompressionandsealingofthewasherleadingtowateringress.
Purpose-designed insulated panel fastenersThesearedesignedwith“dualthreads”.Theloweronesthreadformintothepurlinandaretypically5,5mmdiameter.Attheheadandwasherendofthefastenerthereisatopthreadsectionofanincreaseddiameterdesignedtosupporttheouterskinofthepanelandthusimpartpermanentcompressionofthewasher.
Top thread performanceThishastobedesignedtoaccommodateallpositiveloadingconditionsincludingconcentratedfootloads.Thetopthreadshouldbedesignedtosupportaloadof1.26kNconcentratedonthepanelaroundthefastener.AtestthatcouldbeadoptedisdefinedinBS5427:Part1:1996,AnnexA,ClausesA.4.3&A.5.c.Insulatedpanelfastenersshouldbedesignedwithaminimumtopthreaddiameterof7mmwiththisperformancerequirementinmind.Manyalternativesuppliershavetopthreadssignificantlylessthan7mm,typically6.1-6.4mmmaximum,andthereforethesupportgivenwillinevitablybereducedthusleadingtoaweathersealrisk.
Thread-free sectionForoptimumperformance,designsmayalsoincorporateathread-freefeatureimmediatelybehindandbelowthewasheroninsulatedpanelfasteners.ThisenablestheweatherskintobepermanentlysupportedthuscompressingtheEPDMwasher.Thiscompressionandsealwillbemaintainedeveninconditionswherethefastenerisusedtodrawthepanelbacktothesupportorwherefastenersareoverdriven.Alternativedesignswithtopthreadsextendingrightuptotheheadpresentamajorriskinboththeseconditions.
3.3b Clamping fasteners to ensure weathersealingClampingfastenersarepurpose-designedtoclampthinmaterialstogether(e.g.sidelapsofprofiledmetalsheets)andforfixingflashingsandclosurestoprofiledmetalsheetsandtothemselves.Useofinnappropriatefastenersmayleadtoovertorqueinwhichcase,notonlyisweatherandairtightnesscompromised,butalsothestructuralperformanceofthefastenerislostandcomponentsmaybecomedetached.Clampingfastenersshouldincorporatefeaturestoensurestructuralperformanceandweathertightness.
Reduced diameter drillpoint-highpulloutandclampingforcesWRS washer-thickerandsofter(40shore)thanonprimaryfastenerstoensureasealoverarangeofapplicationthinnesses.Thread free (free spin) zone-todrawandclampthematerialstogetherandtoeliminateanyweatherandairtightnessriskassociatedwithover-driving.
3.4 Specialist warranted sealants to ensure weathersealing Refertosection4.3.
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A designer’s guide to the specification of warranted fasteners and sealants
Insulatedpanelfasteners
Clampingfastener
Section 4 The “Part L” issue - Airsealing & Thermal Bridging
4.1a Overview of April 2002 Part AD-L2A ThechangesintheBuildingRegulations,whichbecameeffectiveinApril2002,soughttoaddresstheproblemsresultinginheatlossthroughthecladdingenvelope.Thosemostrelevanttofastenersandsealantsresultedininsulationthicknessesinthecladdingenvelopevirtuallydoubling(U-valuereductions)andareductionintheproblemofair-leakagethroughthesystemprincipallybyinstallingadditionalairseals.Anothercontributortoheatlossisthermalbridgingthroughthesystem.Thiscouldbethroughpoordesignatjunctionsandalsoviametalfastenerswhichpassthroughthewholesystem,particularlyonmechanicallyfastenedflatroofingsystemswherethereistypicallyahigherdensityoffasteners.
4.1b April 2006 Part AD-L2A England & Wales Part F2:2006 N. Ireland and Section 6:2007 Scotland (in preparation)
AfurtherenhancementoftheRegulationsrequiresthedesignerstousetheNationalCalculationMethodology(NCM)todeterminetheenergyuseofthewholebuilding,includingthefabric,lighting,heating,ventilationandcoolingsystems.Thenewsoftwarecalculationtool-theinterfaceforSimplifiedBuildingEnergyModel(iSBEMv1.2.a)isusedwithintheNCMforbuildingsotherthandwellings.ThetargetistofurtherreducetheTER(TargetEmissionRate)fromthe2002notionalbuildinglevelbyaround24%.
What impact will these changes make on the external cladding envelope?- U-values -Itisgenerallyfeltthat,withthenewcalculationmethodologyforthebuildingsCO2emissions,afurtherreductioninU-values(ie.increasinginsulationthicknesses)ofthecladdingenvelopewillonlyhaveminimaladditionalpracticalimpactonthebuildingsenergyefficiencyoverthechangesalreadyimplementedin2002.
- Natural lighting -Oncertaintypesofbuilding,theprovisionofnaturalrooflightingmayallowareductionintheuseageofelectriclightingthusmakingsignificantcontributionstothebuildingsenergyefficiency.ThiswillusuallymorethancompensateforthehigherU-valuesnormallyassociatedwiththerooflightelementoftheroof.
- Cold Bridging-Elimination/reductioninthermalbridgeswillremainanimportantdesignconsiderationatjunctions,interfacesandfasteners.
- Air-tightness-Increasingair-tightnessfromthe2002levelsof10m3/sqm/hrwillgenerallyshowagreaterbenefitandafurtherincreaseinair-tightnessmaybechosenbythedesignerasasignificantcontributoryfactortocompliancetotheBuildingRegulations.
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4.2 Elimination of cold bridges by using thermally broken fastenersOnmechanicallyfastenedinsulationboardsandroofingmembranes,“thermallybroken”fasteners(Telescope)presentapracticalandeconomicsolution.Itshouldalsobenotedthatthethermalconductivityofausteniticstainlesssteelfastenersisonly25%ofcarbonsteelfasteners(referto2.4c)andthisgivesafurtheroptiononthrough-fixedflatandpitchedcladdingsystems.
4.3 Achieving airtightness with warranted sealants Generally,toachievetheserequiredlevelsofairtightness,additionalsealingmaterialshavetobeincludedwithinthesystem.Thesesealsareusuallyinstalledattheinnerliningpositioniebelowtheinsulation…thefollowingsection4.3givesfurtherinformationonthespecificationoftheseals.
CorusColorshavepublishedaTechnicalPaperentitled“Creatinganair-tightbuildingenvelope-April2006”whichgivesfurtherusefulguidanceonachievingair-tightnessonbuilt-upandinsulatedpanelsystems.
Warranted sealantsThereareanumberofmechanicalandacceleratedtestsdevelopedbysealantmanufacturersforroofingandcladding.ThebasictestsdeemwhetherthesealsareclassedasTypeAorTypeB.TheNFRCpublishedTechnicalBulletin36whichgivesasummary.However,thereisaneedforthesealstobewarrantedforupto30yearsthusbeingcompatiblewiththeausteniticstainlessfastenersandsheetsystemasreferredtoinsection2.5.SFSintecworkedcloselywithaleadingsealantmanufactureranddevelopedahighperformancebutylstripsealantrangeforprofiledroofingandwallingsystems.TheirperformanceunderallthemechanicalandacceleratedtestsexceededthebasicrequirementofaTypeAsealantsuchthatSFSintecareabletoissueawarrantyforupto30years.ThiswarrantedSFSintecsealantisreferredtoasTypeA+andiscolouredpinkforeaseofidentification.
Clamping fasteners (referto3.3b)
Toensurethatthewarrantedsealantsperformeffectivelywithintheapplication,theyhavetoworkincombinationwiththepurposedesignedclampingfastenersdiscussedwithinsection3.3b.
A designer’s guide to the specification of warranted fasteners and sealants
ThreadfreezoneforweathertightclampingonSFSstitchingfasteners
Coldbridgingviaall-carbonsteelfasteners
Section 5 Aesthetics by designHistorical backgroundDuringthe1970s,themarketshareforcolour-coatedcladdingmaterialsdramaticallyincreasedprincipallywithintheindustrialandretailbuildingsectors,andtodaycolour-coatedcladdingrepresentsover90%oftheirtotalmarket.
Colour-coatedmaterialsarealsonowwidelyusedaspartofthecladdingenvelopeonmanyotherbuildingtypessuchaseducational,healthcare,residential,leisureandtransport-relatedbuildings.
Freedom of designTherangeofshapesandprofilestowhichthesecolouredmaterialscanbeformedhasgiventhearchitectmuchfreedomofdesignandgreatattentionisnowpaidtotheaestheticsofconstructiondetailsandinterfacesratherthanmerelytheirfunctionalperformance.Designersareabletousecolourandshapetocreateaestheticappealandimpacttoattractinvestorsandtosupporttheirclientscorporateimage.
Colouring of fastenersWherevisiblefastenersareusedtosecurethesecolouredmaterials,itis,virtuallywithoutexception,desirablethatthefastenerheadispermanentlycoloured.
5.1 The problemSomecontractorsmaychoosetofixthecolouredcladdingmaterialswithplainhexagonalheadedfastenersandthensite-applyapush-fitcolourcap.
There are many potential problems with this option;
i)Capsmaybemissedoff
ii)Capsmaybecomedislodgedafterinstallation
iii)Capsareexpensivetoreplace
iv)The“plastic”maysufferUVdegradation
v)Thecapmaysufferfromcolourinstability
vi)Capsmayentrapmoisture-leadingtocorrosionstaining
vii) Capsdonotofferlifespansmatchingthecladding
viii) Capsareslowtoinstall
Theseareproblemsforboththecontractor,whomayhavetomakereturnvisitstoreplacecaps(snagging),andtothebuildingownerwhosuffersalossofaestheticappealandimageandtheexpenseassociatedwithrestoringtheoriginalintendedfinish.
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5.2 Factory-coloured solutionsToaddressthemanyproblemsassociatedwithpush-fitcaps,SFSintechasdevelopedrangesofcolouredandaestheticallyshapedfasteningsystemswhichhaveevolvedwiththeintroductionofnewcladdingmaterialsandprofiles.Thesehavebeendesignedwiththedesiresofthespecifiers,contractorsandbuildingownerstakenintoconsideration.
5.2a The moulded head solutionTheoriginalSelacolouredheadwasdevelopedbackinthe1980sandisproducedbyinjectionmouldingthethrough-coloureddryvirginnylonaroundthemetalheadformofthefastenertoformanintegralbi-hexagonalcolouredhead.Thistraditionalmouldeddesignensuresapermanentcolour-matchedheadfromthemomentofinstallation,thusprovidingthecontractorandbuildingownerwithasimplesolutiontoalltheproblemsassociatedwithpush-fitcaps.
5.2b The “unobtrusive” solutionWherethedesignerselectsawallcladdingmaterialorprofileforitshighaestheticappeal,itmaybemoredesirablethatthefasteningsystemisunobtrusiveandblendsinwiththecladding.Somewallingsystemsaredesignedsuchthatthefastenersaretotallyconcealed,forexample,flatormicro-ribbedinsulatedwallpanelsareoftenfixedthroughtheir“tongue&groove”joint.
However,therearemanywallingsystemswhicharevisiblyfixedandtheraisedheadsoftraditionalmouldedheadedfasteners,eventhoughtheymayofferlongtermcolourmatching,maynotmeettheaestheticrequirements.
Lowprofilecolouredheadformshavebeendevelopedspecificallyforapplicationswherethefastenerhastofulfillallitsnormalstructuralrequirementswhilst,atthesametime,blendinunobtrusivelywiththecladding.
Theirius®headformmaybepowdercoatedforcolourmatchingpurposesandtheinnovativeunderheaddrivesystemenableseaseofinstallationwhilstalsoofferingahighleveloftamper-resistance-aestheticswithsecurity.
A designer’s guide to the specification of warranted fasteners and sealants
Selaheadform
Irius®headform
UnobtrusiveIrius®atWalesMillenniumCentre
ColouredIrius®headform
5.2c The “obtrusive” solutionAsacompleteoppositetothe“unobtrusive”headstyleoftheirius®range,thedesignermaywishthatthefastenersaredeliberately“obtrusive”andcreatesurfacefeatureson,forexample,flatcladdingpanels.
SFSintecthereforedevelopedthedesignerrangeoffastenerswheretheboldoutstandingheadformishighlyvisible.
Thereisarangeofprofileheadsineitherausteniticstainlessoraluminium,whichmaybepowdercoatedforcolourmatchingorcontrastingpurposes.
Thefeatureheadsaremanuallyscrewedontothemalethreadontheheadoftheprimaryfastenerwhichsecuresthepanelstothestructure.
Topreventtheheadsfrombeingremoved,forexampleoninstanceswherethefastenersmaybewithinreach,theyarefactory-coatedwithathreadlockingcompoundwhichisactivatedduringapplication.
5.2d Glass attachment with style and eleganceGlasshasneverbeeninsomuchusearchitecturally.Therearestructurallystrongandaestheticallypleasingfixingsystemsavailableforavarietyofglassapplications;
Single-point fixings-Single-pointglassfixingsystemsaredesignedtomeetthestringentrequirementsintermsofboththeirvisualappearanceandtheirstructuralsafety.Thecombinationofchromiumandglassoffersanappealingeffectpopularwithbothclientsandarchitectsalike.Combiningthepracticalwiththeaestheticallypleasingoftencreatesrealarchitecturalworksofart.
Canopy attachment systems-Canopysystemsarenowavailableasaninnovativetotalpackagewhichenablesglasscanopiestobeattachedwithsingle-pointglassretainers.Theindividualcomponentsofthesystemcanbecombinedtosuitthetypeofcanopyandsubstructure.Theentiresystemremainsbiaxiallyflexiblethroughtheuseofforksandrings.Theadvantageofthisisthatthecanopystructureisresistanttopressureandsuctionloading.
Balustrades and Staircases-Glassfixingsalsoenablebanistersandbalustradestobecreatedsimplyandeconomically.Theholdersaredesignedassleeves.Noweldingonsiteisnecessaryastheretainersarefastenedwithpress-fitnutsandcorrespondingbolts.Highqualitymaterialsandfinishesprovideapermanentandsecureretentionoftheglasspanels.
SFSinteccanworkwiththearchitectandglasssystemsuppliertoprovidefixingsolutions.
A designer’s guide to the specification of warranted fasteners and sealants
email: [email protected]: 0113 2085 578TechnicalFax: 0113 2085 539 29
Sectio
n 6Technical
Section 6 Technical performance criteriaApartfromdurability,weathersealing,airsealing,andaesthetics,fastenershavetobecapableofwithstandingawiderangeofloadingsandotherperformancecriteria.Thesetechnicalperformancecriteriatendtobespecifictotheparticulartypeofcladdingsystemandthereforefastenersaredesignedsuchastogiveoptimumperformancecompatiblewiththerequirementsoftheparticularsystem.
Typicaltechnicalperformancecriteriawhichinfluencefastenerdesigninclude;
6.1 Pullout and tensile forces 6.9 Clamping & sealing6.2 Pullover resistance 6.10 Shear performance6.3 Concentrated foot loadings 6.11 Non-fragility6.4 Dynamic bend resistance 6.12 Material compatibility6.5 Unwinding 6.13 Windloadings 6.6 Clamping of membrane 6.14 Fastener frequencies 6.7 Thermal/cold bridging 6.15 Tooling6.8 Overdriving resistance
6.1 Pullout and tensile resistanceThisistheabilityofthefastenersthreadedconnectionbetweenthetwocomponentstoremainintactandresistallaxialandtensileloadings.
Selfdrilling fastenersItisnowawidelyacceptedindustrypracticethatselfdrillingfasteners,whichareinstalledinasingleoperation,arepreferredtotappers,whichrequiretheadditionalpredrillingoperation.
Selfdrillersarenowavailableforthemajorityofcladdingsystemsformetalsupportthicknessesupto14mm.
Thebenefitofselfdrillersisnotlimitedtotheobviousoneoftimesaving.Selfdrillersalsoprovidemoreconsistentandoptimumpulloutresistancefromthesupportingmaterial.Tappersrequiretheinstallertouseanon-worndrillofthecorrectdiameterspecifictothemetalthickness,andtopredrillwithoutwobble,otherwisethepulloutvaluesachievedwillbevaried(ahighstandarddeviation)andsignificantlylowerthanpublisheddatafromlaboratorytesting.
Selfdrillersaremanufacturedwiththeirownintegraldrillpointswhichareengineeredtoefficientlydrillandthreadformintoapredeterminedmetalthickness,resultinginmuchmoreconsistentperformancethusreflectingpublishedtestvalues.
Thedrillpointdiameterandlengthispurpose-designedforaspecificrangeofmetalthicknesses.
Toassisttheengineerandspecifier,SFSintecpublishesresultsoflaboratorytestingonallfasteners.Thisincludesfastenerpullout,showingthemeanultimatefailureloadandalsothestandarddeviation.Thisenablesthecalculationofthecharacteristicvalueforeachfastenertowhichanappropriatesafetyfactorcanthenbeapplied.BS5427:Part1:1996AnnexBmaybeusedforreference.
A designer’s guide to the specification of warranted fasteners and sealants
Pullouttesting
Purpose-designeddrillpoints
Section 6 Technical performance criteria continued
6.2 Pullover resistanceThisistheabilityofthefastenertopreventthesheetmaterialfailingbypullingovertheheadofthefastener.
AsreferredtoinSection3onWeathersealing,resistancetopulloverfailureofthesheetisinfluencedbythesheetmaterialthicknessandtensilestrengthincombinationwiththestrengthanddiameterofthewasher.
Thefastenersupplierspecifiedshouldbeabletoprovidetheengineerwithpublishedtestresultsofvariouswasherdiametersinvarioussheetmaterialsandthicknesses.
6.3 Concentrated foot loadingsThetwoprincipleapplicationswherefootloadingshavetobeconsideredinfastenerdesignaremetalfacedinsulatedroofpanelsandsingleplyroofmembranesoverinsulationboards
Insulated roof panels
AsdescribedinSection3.3a,thetopthreadofinsulatedpanelfastenershastobedesignedsothatitwillcontinuetosupporttheexternalskinofthepanelagainsttheconcentrateddynamicloadsimpartedbyfoot-traffic.Withtheappropriatesafetyfactor,thetopthreadshouldbedesignedtosupportaloadof1.26kNconcentratedonthepanelaroundthefastener.AtestthatcouldbeadoptedisdefinedinBS5427:Part1:1996,Codeofpracticefor:Theuseofprofiledsheetforroofandwallcladdingonbuildings,AnnexA,ClausesA.4.3&A.5.c.
SFSintecsinsulatedpanelfastenersaredesignedwithaminimumtopthreaddiameterof7mmwiththisperformancerequirementinmind.
Manyalternativesuppliershavetopthreadssignificantlylessthan7mm,typically6.0-6.4mm,andthereforethesupportgivenwillinevitablybereducedthusleadingtoaweathersealrisk.
Thisenlargedthreadalsoworksincombinationwiththethread-freezone,whosefunctionisalsodescribedinSection3.3a,toensurebothawalkableandweathertightconnection.
Single ply membranes over insulation boards
Themembranemustbeprotectedagainsttheriskoftheinsulationandmembranefastenerpuncturingthemembraneasaresultoffoottrafficcausinglocalcompressionoftheinsulationboard.
TelescopesystemssuchastheSFSintecIsotakrangeareautomatically“treadfast”asthefastenerheadissetdowntowardsthebottomofthetelescope.
Onallmetalfastener/washercombinations,thefastenershouldhaveanenlargedthreadontowhichtheinsulationandseamwasherissupported.
A designer’s guide to the specification of warranted fasteners and sealants
Pullovertesting
SheetsupportandthreadfreesectiononSFSinsulatedpanelfasteners
“Treadfast”telescope
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6.4 Dynamic bend resistanceWhereinsulatedpanelsarethrough-fixed,thefastenersarealsosubjecttorepetitivebendingforces.Theseforcesaretypicallygeneratedbypaneldeflectionsfrom(wind)loadingsandthermalmovement.Thisbendingtendstobegreaterinhot-rolledsteelpurlinswhichtendtobelessflexiblethanthinnercold-rolledpurlins.
TheEuropeanConventionforConstructionalSteelwork(ECCS)Document66,PreliminaryRecommendationsforSandwichPanelsdefinesatestmethodtowhichfastenermanufacturershavetobeabletodemonstratecomplianceandadvisethemaximumallowabledeflectionrelativetosteelsupportandpanelthickness.
6.5 UnwindingPitched roofing systemsHistorically,thisphenomenomhasnotbeenwidespreadwithinpitchedroofingsystems.However,whereconditionsofpotentiallyhighdifferentialmovementbetweenthesheetand“lightweight”framingpresentthemselves,cautionintheselectionofthemostappropriatefastenertypeshouldbeexercised,andSFSintecwouldwelcomebeingconsulted.
Flexible membrane systems to “thin” metal decksAsthewindpassesovertheflexiblemembraneaneccentricforcepassesthroughthefastener.TheSFSisofastsystemisabletoaccommodatethesedynamicwindloadsbynatureofits“reduced”diameterdrillpoint,thetaperedlead-inthreadsectionanditsshallowthreadpitchangle.Thesefeaturescombinetogivetotalthreadengagementwithinthedeckandtoalsoprovidetheoptimumpulloutfrom“thin”,0.63mmminimum,steeldecks.
6.6 Clamping of membraneOnin-seamfastenedsingleplymembranes,thewasherorstressplateisdesignedtoresistanysidewardsmovementofthemembranewhichcouldultimatelyleadtotearing,slippageandfailureofthemembrane.SFSinteccanofferavarietyofstressplatedesignswhich,duetotheirhighclampingqualitiesmayallowa25%increaseinthefastenersafeworkingload.
Unlessthemembranesuppliertakesfullresponsibilityforthefastenerfrequencycalculations,confirmationshouldbesoughtfromtheparticularmembranesupplierthattheproposedfasteningsystemanditspermissibleloadingsareappropriatetotheirmembrane.
6.7 Thermal/cold bridgingApprovedDocumentAD-L2:2006requiresthedesignertocalculatethermalbridgesandconsidertheireffectonbothcondensationandalsoheatlossthroughthebuildingenvelope.
Incertaintypesofroofingandcladdingsystems,fastenersmayaddtoheatlossdependingontheirspecification.
Thethermalconductivityofcarbonsteelasafastenermaterialis60W/mKwhereasausteniticstainlessisonly17W/mK.ThereforespecifyingausteniticmayallowthinnerinsulationtobeusedandstillachievecompliancewiththeBuildingRegulations.
Asanexample,inatypicalflatroofapplicationwith4fastenerspersqm,theadditionalheatlossthrough100mminsulationwithcarbonfastenersexceeds1.5%comparedtoonly0.25%withausteniticstainlessfasteners.Wherecoatedcarbonsteelofferssufficientdurability,thenusingathermallybrokentelescopicsystem(seesection4.2)wouldalsoallowthinnerinsulationtobeused.
A designer’s guide to the specification of warranted fasteners and sealants
SFSisofastdrillpointandthreadform
Coldbridgingviaall-carbonsteelfasteners
ECCSBendtest
Section 6 Technical performance criteria continued
6.8 Overdriving resistanceOverdrivingoffastenersmayleadtothreadstrippingwithinthesupportingstructure,particularlyin“thin”coldrolledsections.“Traditional”designsofselfdrillingthreadedfastenersrelyupontheinstallertotakethenecessarycarenottooverdrive,eitherbyuseofdepthlocatorsonscrewgunsorexperience.Fortwoparticularapplicationswherethefastenerperformanceiscriticialfortheintegrityofthesystem,SFSintechasdevelopedinnovativesolutionswhich,bydesign,cannotbeoverdriven.
SDK fasteners for aluminium haltersDuetothehighexpansionrateofaluminiumsheets,fastenerssecuringhaltersforaluminiumstandingseamsystems,suchasKalZip,EuroseamandKeyBemo,oftenhavetowithstandveryhighandrepetitiveshear/tensileforces.Toeliminatetheriskofsystemfailureduetooverdrivenfasteners,theSDKdesignoffastenerisdrivenviathesquarepegontheheadwhichisdesignedtobreakoffwhenthefasteneristightenedtothecorrectlevel.
“Thick to thin” applicationsOnsomebuilt-upmetalsystems,particularlywherethereisanacousticand/orhighinsulationrequirement,a“thick”tophatmaybeinstalledontothe“thin”liner/deck.Traditionallyarivetwouldhavebeenusedastheriskofoverdrivingwith“standarddesign”drillersisconsideredtoogreat.Howeverarivetisextremelyslowtoinstall.
SFSintecdevelopedtheselfdrillingfastenershownoppositewhichcombinesspeedwithsecurity-thefastenercannotbeoverdrivenasthespeciallydesignedwasherflattenswithinthefree-spinzonetoaccommodatethecombinedthicknessesofthetophatandliner/deck.
6.9 Clamping & sealingInSections3and4theimportanceoffastenerswithregardsweatherandairsealingwasdiscussed.SFSintecsstitchingandclampingfastenersarepurpose-designed.BehindthesoftEPDMwasherisanunthreaded(free-spin)zonewhichenablesthetwothinsheetstobedrawnandclampedtogetherthuscompressingtheweatherorairsealant.
6.10 Shear performanceInsomeapplicationsfastenersaresubjectedtoadirectshearloading.SFSintecpublishesdocumentationwhichgivestheengineertheshearvalueofthefastenerandalsoofthefastenerinarangeofapplications.
6.11 Non-fragilityTheAdvisoryCommitteeforRoofwork(ACR)publishanumberofguidancedocumentswhichallcontributetotheaimofenablingroofworktobedesignedandcarriedoutwithminimalrisktoanypersonnelwhoeitherconstructtherooforwhosubsequentlyneedtotrafficacompletedroof.
Fastenertypesandfrequenciesplayamajorroleinachievinganon-fragilestatusformetalroofsystemsandtheRedBook-ACR[M]001:2005detailsthetestingmethodologyfornon-fragility.
Important note:itisnowacceptedpracticetouse5.5mmdiameterwasheredfastenersforroofliningpanelsratherthan4.8mmnon-washeredfasteners.Forlongtermnon-fragilitybeyondtheconstructionphase,austenitic stainlesssteel fastenerswouldbetherecommendedchoiceduetotheirprovendurability.
A designer’s guide to the specification of warranted fasteners and sealants
SFSintecclampingfastener
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6.12 Material compatibilityTheriskofcorrosionofthesheetmaterialduetothefastenerandalsothefastenerduetothematerialitisfasteninginto/throughhastobeconsideredbythedesigner.
Bi-metallic corrosionPD6484:1979-“Commentaryoncorrosionatbimetalliccontactsanditsalleviation”maybereferredtoinorderthatanyriskcouldbeassessed.Considerationmustalsobemadetotherelativesurfaceareasofthemetalsincontactandthemoisturecontentaroundtheconnection.Generally,thefastenermustbemorecorrosion-resistantthanthematerialitisfasteninginto/through.Therefore,itisconsideredappropriateforausteniticstainlessfastenerstobeusedincombinationwithaluminiumorgalvanizedsteelsheets/supports.Zinccoatedcarbonsteelfastenersshouldonlybeconsideredforgalvanizedsheets-refertotableinsection2.6.
Corrosion within timberTimbermaybeincorporatedintotheroofingandcladdingsystemasabeam,purlin,spacer,counterbattenand/ortilingbatten.Timberisamoistureabsorbentmaterialandsotoprolongthelifeoftimberitmaybetreatedwithapreservative.Thesetreatmentsaretypicallydividedintotwotypes-OrganicSolvents(OS)andCopperChromeArsenic(CCA)andarecoveredinBS4072:Part2:1987andBS5268:Part5:1989.
TheCCAtreatments,inparticular,canbeverycorrosivetozinccoatedcarbonsteelfastenersanditisthereforerecommendedthatwithCCAtreatments,andalsowithOStreatmentsifthemoisturecontentislikelytobeat>15%forprolongedperiods,austeniticstainlessfastenersbespecified.
6.13 WindloadingsBS6399:Pt2:1997isthecodeofpracticeforwindloadsandisreferencedintheBuildingRegulationsforEngland,ScotlandandWales.InIreland,CP3:ChapterV:1972isreferenced.
WindloaddataisoftenprovidedbytheEngineer,andusedbytheContractorand/orthesystemsupplierinthedetaileddesignandspecificationoftheroofingandcladdingsystem.
Wherethisinformationisnotavailable,fastenersuppliersmaybeconsultedtoassist,uponrequest,andsubmitwindloadcalculationsrelevantforthefasteningproposalsoftheroofingandcladdingsystem.Suchcalculationsshouldbeverifiedbytheprojectengineer.6.14 Fastener frequenciesSFSintecpublishesawiderangeoftechnicalperformancedataonitsfasteners.Generallythepublishedvaluesaretheultimatemeanandthestandarddeviationvalues.Safetyfactorshavetobeappliedtothesefigurestoestablishthesafeworkingloadofthefastener.BS5427:Pt1:1996AnnexBgivesguidanceonthiscalculation.SFSinteccanhelpinterprettheseloadsrelativetotheproposedroofingandcladdingsystem.
Theremayalsobetestdatacompiledbythesystemmanufacturerfromwhichthemaximumallowablefastenerloadshavebeendetermined.
Onceallrelevantloadings,structuralframedetailsandtheproposedroofingandcladdingsystemspecificationhavebeenestablished,thefastenersuppliermaybecalledupontoworkincloseco-operationwiththerelevantparty,eg.designer,systemsupplier,contractor,todeterminethefastenerfrequenciesspecifictotheproject.
6.15 ToolingSections6.1to6.14showsthewiderangeofperformancecriteriafastenershavetobecapableofwithstanding.Thesecriteriatendtobespecifictotheparticulartypeofroofingandcladdingsystemandthereforefastenersaredesignedsuchastogiveoptimumperformancecompatiblewiththerequirementsoftheparticularsystem.Whilstsomefastenershavebeendesignedsuchthattheycannotbemis-installed(referto6.8&6.9),toolingsystemsforotherfastenertypesareavailablewhichassisttheContractorintermsofbothspeedandconsistency,aswellasprovidingsecuritytotheClient.
A designer’s guide to the specification of warranted fasteners and sealants
Windcreates+veand-ve(suction)loadsonroofingandcladding
Sectio
n 7S
pecifi
cation
Section 7 Specification design support
7.1 Fastener and sealant specifications for roofing and cladding
Specification advisory service for architects and designersAttheearlydetaildesignstageofaprojectcomplexandsometimesconflictingrequirementscanplacediversedemandsonthefastenerandsealants.Consultationwithanexperiencedtechnicalteamfromthefastenersuppliercanhelpyoutoresolvefastenerandsealingissuesduringtheplanningstages,workingsidebysidewitharchitectsanddesignerstoensurethatperformancerequirementsofthebuildingenvolopearemet,andthecontractspecificationproceedswithoutahitch.
Assessing and specifying the right productsEverycontractisdifferent,andwiththeincreasingnumberofproductsonthemarket,andevermorepressureonyourtime,justhowdoyousiftthroughthemassofinformationavailabletospecifythecorrectfastenersandsealants.
The answer is to let SFS intec help.
TheSFSintecspecificationteamisgeareduptoworkingwitharchitects,designers,contractorsandstructuralengineerstoprovideinformed,detailedandreliablespecificationguidance.
SFSinteccanprepareproject-specificfastenerandsealantspecificationsforinclusionwithintenderdocumentation.Thesespecificationsmaybeineitherprescriptiveorperformanceformatasadoptedbytheparticularpractice.
NBS Plus ForthosethatprescribetoNBS,SFSintecausteniticstainlessfastenersandwarrantedsealantsarenowlistedwithinNBSPlus,partoftheNBSindustrystandardspecificationsoftwareusedbyarchitects,engineers,buildingsurveyorsandotherconstructionindustryprofessionals.ThismeansthatthetechnicalinformationandguidanceforourproductsispresentedtoNBSsubscribers,inNBSformat,atthepointinthespecificationappropriatetoourproducts.Furthermoreyouwillbeabletoaccessourwebsitewww.sfsintec.biz/ukthroughthedirectlinkfromNBSPlustoobtainfurtherinformation.WecanalsoprovideguidanceforthecompletionofNBSclausesuponrequest.AllinformationfoundwithinNBSPlusisupdatedthreetimesayearensuringthatspecifiershaveaccesstoourmostrecentproductinformation.
CPD seminars SFSintecalsooffertheirRIBA-accreditedCPDtechnicalseminarwhich,inconjunctionwiththisguide,helpsyoutobecomefamiliarwithissuesconcerningfastenersandsealants,aswellasenablingyoutoacquireyourRIBACPDpoints!Contactusonthedetailsbelow.
A designer’s guide to the specification of warranted fasteners and sealants
email: [email protected]: 0113 2085 578TechnicalFax: 0113 2085 539 35
A designer’s guide to the specification of warranted fasteners and sealants
Examplespecificationforprimarylinerpanelfasteners.
Examplespecificationforinsulatedpanelfasteners.
Examplespecificationforsealants. ExamplespecificationforinsulatedpanelfastenersandsealantpreparedinNBSformat.
7.1a Project-based specification sheets
Examplesofthetypesofproject-basedspecificationsforfastenersandsealantsareshownbelow.ByusingthecodesanddescriptionspreparedbySFSintec,thespecifierhasthechoiceofissuingspecificationsineitherperformance,prescriptiveorNBSformats.
7.2 Innovative solutions to benefit everyone – from architect through to client Asbuildingdesignmovesforward,architects,designers,andcontractorsfacenewchallengesandnewproblems–whichmustbemetwithinnovativeproductsolutions.AtSFSintecweaimtomeet–andexceed–yourexpectationsofproductperformancethroughconstantresearchanddevelopmentintopractical,effectivefastenersandairsealingsolutions.Throughourcloserelationshipwithtesthouses,researchlaboratoriesandmanufacturersofroofingandcladdingsystems,plusourownin-houseresearchintometallurgy,drilltechnologyandcorrosiontesting,weareabletobringyouthemosttechnologicallyadvancedsolutionstotoday’smarketneeds.
Long-term partnerships with roofing system suppliersRoofingandcladdingsystemmanufacturersareconstantlyimprovinganddevelopingtheirproducts,andSFSintecismatchingthesedevelopmentswithnewfastenertechnologies.IntheUKandworldwide,SFSintectechnicalspecialistsareworkinginpartnershipwiththemarketleadingsystemmanufacturersinexternalcladding,insulationsystemsandroofingsystemstobringcompetitive,high-performancefastenersolutionstothemarket.SFSintecproductsareendorsed–sometimesexclusively–bymanyoftheUKindustry’smajorsystemssupplierssuchasCorusPanelsandProfilesandtheirPlatinumWarrantySystem–testimonytoourcommitmenttoapartnershipapproachtoprovidingpractical,customisedsolutionsfortoday’scompetitivemarket.
Adding value to the project: the SFS intec quality guaranteeInthiscompetitivemarket,clientsarealwayslookingforaddedvalue–whetheritmeansahigherlevelofspecification,greaterlongevityofthebuilding,lowmaintenanceorimprovedperformance.Creatingthataddedvaluemeansbeingabletorelyoneventhesmallestcomponentinthebuildingtosupportthedemandforoverallquality.
Recognisedworldwideforitscommitmenttothehigheststandardsofproductperformanceandcustomerservice,SFSintecfastenerproductsandairsealingsolutionscanplayanimportantpartinhelpingyoutodelivercustomersatisfaction.ThroughouttheSFSintecorganisation,specialised,on-goingtrainingensuresthatyoubenefitfromaninformed,technicallyawareandexperiencedteam–atalllevels.Intermsofproduction,theSFSintecexactingqualityassurancesystemstandsuptoanyinternationalrequirement,soyoucanhavecompleteconfidenceinthetechnicalvaluesandperformancespecificationsoftheproductsyouspecifyanduse.
Quality and environmentSFSintecproductsandinstallationsystemsaremanufacturedtothehighestqualitystandards,soyoucanspecifywithconfidence.Since1987,SFSintechasbeencertifiedtoISO9001.Earlyin1996,ourmainmanufacturingplantgainedtheISO14001environmentalstandardalongwithVDANo6.Fromproductionthroughtopackaging,wedon’tjustaimtomeetquality,environmentalandsafetyrequirements–weworktoexceedthem.
A designer’s guide to the specification of warranted fasteners and sealants
CorusPanelsandProfilesLtdPlatinumWarranty
email: [email protected]: 0113 2085 578TechnicalFax: 0113 2085 539 37
7.3 Achieving results through technical advisory service
Helping you choose the right fastening systemChoosingtherightfasteningsystemcanbedecisiveintermsofthelongevityandsafetyoftheroof.AswellasoutliningSFSintec’spolicyoncustomerservice,fastenerproductdevelopmentandcost-effectivesystemstechnology,thisproductselectorgivesyouaclearguidetothemostsuitablefastenersfordifferentapplicationswithinthefieldofpitchedroofingandcladding,makingspecificationquickerandsimpler.Butifyoudoneedpersonaladvice,pleasedon’thesitatetogetintouchwithourtechnicalteamwhocanadviseyoufurther.
Total technical support from specification to site testsIncorrectcalculations,specificationdetailsorinstallationcanleadtocostlydelaysonsite.Butasthedemandsonbuildingstructuresincrease,andthevarietyofoptionswidens,choosingthecorrectfastenerandairsealingsolutionforthejobisbecomingmoreofatestingtask.Tohelpyoutogetthingsrightfromstarttofinish,theSFSintectechnicalteamiscommittedtoprovidingyouwiththesupportyouneed,including:
• Expert product specification and air sealing solution advice.• Guidance on choosing a system to meet the specific warranty requirements of your contract.• Training your team in the best use of your chosen system.• Help with calculating fastener quantities and costs.• Informed, reliable technical help whenever you need it throughout the contract.
7.4 TrainingCPD seminars SFSintecalsooffertheirRIBA-accreditedCPDtechnicalseminarwhich,inconjunctionwiththisguide,helpsyoutobecomefamiliarwithissuesconcerningfastenersandsealants,aswellasenablingyoutoacquireyourRIBACPDpoints!Contactusonthedetailsbelow.
On-site trainingPrecisionduringinstallationcanbethedifferencebetweenasecurerooforperformanceproblems.Tohelpyoueliminateanyrisk,SFSintecoffersfreetrainingintheuseofSFSinteconsitefastenerinstallationtools,whicharepurpose-designedensuringthatconsistencyoffixingisachieved.Whetheryourequireoneofourtechnicaltrainingteamtocarryouttrainingon-site,oryouprefertovisitthetechnicaltrainingcentreatourLeedsoffices,ourexpertiseisonlyaphone-callaway.
A designer’s guide to the specification of warranted fasteners and sealants
Section 8 Case studies
8.1 Heathrow Airport, Terminal 5
Specialist contractor; HathawayRoofingLtd Project requirements; Durability Section 2.5b & d Componentsupplierwarranty Section 2.5e Aesthetics Section 5 Technicalperformance Section 6 Designsupport Section 7
SFS intec products; Austeniticstainlesssteel Section 2.7 SFSproject-specificwarranty Section 2.5e iii) irius®colourheads Section 5.2b SDKhalterfixings Section 1.3a & 6.8 Clampingfasteners Section 3.3, 4.3, 6.9 Technical&designsupport Section 6 & 7
A designer’s guide to the specification of warranted fasteners and sealants
Sectio
n 8C
ase studies
email: [email protected]: 0113 2085 578TechnicalFax: 0113 2085 539 39
A designer’s guide to the specification of warranted fasteners and sealants
Section 8 Case studies
8.2 British Car Auctions, Bedford
Specialist contractor; CommercialCladdingServicesLtd Project requirements; Durability Section 2.5b Systemsupplierswarranty Section 2.5e Aesthetics Section 5 Weather&airsealing Section 3 & 4 Technicalperformance Section 6
SFS intec products; Austeniticstainlesssteel Section 2.7 Project-warrantytosystemsupplier Section 2.5e ii) irius®colourheads Section 5.2b Clampingfasteners Section 3.3, 4.3, 6.9 Weather&airsealantsTypeA+ Section 3.4 & 4.3
A designer’s guide to the specification of warranted fasteners and sealants
Section 8 Case studies
8.3 Wales Millennium Centre, Cardiff
Specialist contractor; KelseyRoofingIndustriesLtd Project requirements; Durability Section 2.5b & c Componentsupplierwarranty Section 2.5e Aesthetics Section 5 Technicalperformance Section 6 Designsupport Section 7
SFS intec products; Austeniticstainlesssteel Section 2.7 SFSproject-specificwarranty Section 2.5e iii) irius®colourheads Section 5.2b SDKhalterfixings Section 1.3a & 6.8 Clampingfasteners Section 3.3, 4.3, 6.9 Technical&designsupport Section 6 & 7
A designer’s guide to the specification of warranted fasteners and sealants
NOTES
To make you more competitive.
SFS intec Ltd.Fastening Systems153 Kirkstall RoadLeeds LS4 2AT
Tel: 0113 2085 500Fax: 0113 2085 539Email: [email protected]: www.sfsintec.biz/uk
For further information please contact:
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CPD seminars SFSintecofferstheirRIBA-accreditedCPDtechnicalseminarwhich,inconjunctionwiththisguide,helpsyoutobecomefamiliarwithissuesconcerningfastenersandsealants,aswellasenablingyoutoacquireyourRIBACPDpoints!Contactusonthedetailsbelow.