A designer’s guide to specifying warranted 316 austenitic ... · 1.1 Performance criteria of fasteners and sealants 3 1.2 Industry associations and partnerships with leading system

CI/SfB Reference by RIBA SfB Agency

Xt6October 2015

A designer’s guide to specifying warranted 316 austenitic stainless steel fasteners and sealants

WelcometothelatesteditionoftheSFS“Adesigner’sguidetospecifyingwarranted316austeniticstainlesssteelfastenersandsealants”.

WehaverevisedandupdatedthepublicationtoreflectchangesinourproductsandservicestomeetchangesinUKconstructionlaw.InparticularthemandatoryuseofCEmarkingforconstructionmaterialsfrom2013togetherwiththeintroductionofnewENandrevisedBSstandardswhicharereplacingtheoldBSversionsacrossalldisciplines.Forexample,fordurabilitystandards,wenowworktoEN12944andthe2015revisededitionofBS7543andforwindloads,EN1991ratherthanBS6399.

ThesenewENstandardsareinsomecasesmoreonerousthantheoutgoingBSbuthaveadistinctadvantageinthattheyarerecognisedEurope-wide,simplifyingregulationandcross-bordertradingatatimewhenUKconstructorsareincreasinglylookingtoEuropeforbusinessopportunities.

email: [email protected] Helpline: 0113 2085 578

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Contents

Introduction to the SFS Group of companies

Section 1 Introduction 3 1.1 Performancecriteriaoffastenersandsealants 3 1.2 Industryassociationsandpartnershipswithleadingsystemsuppliers 3 1.3 Examplesofrecentinnovations 4

Section 2 Durability (corrosion resistance) 5 2.1 Theproblem 2.2 Fastenermaterials 6 2.3 Limitationsofcoatedcarbonsteel 7 2.4 Typesofstainlesssteel 8-9 2.5 Carbonorstainless?Specificationselectionconsiderations 10 2.5aSystemmaterials 11 2.5bDesignliferequirements 12-13 2.5cExternalenvironment 14 2.5dInternalenvironment/buildinguse 15 2.5eProject-basedlongtermwarrantyrequirements 16 2.6 Fastenermaterialselectortable 17 2.7 SFSintecausteniticstainlesssteelfastenerrange 18-19

Section 3 Weathersealing 20 3.1 Theproblem 20 3.2 Washerdesign 21 3.3 Specialistfastenerdesignforweathersealing 22

Section 4 The “Part L” issue - Airsealing and thermal bridging 23 4.1 OverviewofBuildingRegulations-2002,2006,2010&2013-Theproblem 23 4.2 Eliminationofthermalbridgingbythermallybrokenfasteners 24 4.3 Achievingairtightnesswithwarrantedsealants&clampingfasteners 24

Section 5 Aesthetics by design 25 5.1 Theproblem 25 5.2 Factory-colouredsolutions 26 5.2a Paintedheadsolution 26 5.2b Unobtrusiveheadsolution 26

Section 6 Technical performance 27 6.1-6.15 Technicalperformancecriteria 27-31

Section 7 Specification design support 32 7.1 Modelspecifications 32-33 7.2 Innovationandquality 34 7.3 Technicaladvisoryservice 35 7.4 Training-CPDSeminarsandon-site 35

Section 8 Case studies 36

Co

ntentsContents

www.sfsintec.biz/uk2

Introduction to the SFS Group of companies

TheSFSGroupofcompanies,whichhasitsheadquartersinHeerbrugg,Switzerland,isoneoftheworldsleadingdevelopers,manufacturersandsuppliersofhighprecisioncomponentsforavarietyoftechnicalindustries.

TheSFSGroupdirectlyemploysover7000personnelandin2014turnedover£880million.

Global manufacturingThegroupmanufacturesglobally,withplantsacrossEurope,NorthAmerica,ScandinaviaandAsia.

Global sales and marketingProductsaresuppliedintotheglobalmarketthrough70SFSsalesandmarketingorganisationsstrategicallylocatedin25countries.

UK headquartersTheUKheadquarters,whichincludesmanufacture,logistics,andsalesandmarketing,isbasedinLeeds.FastenershavebeenmanufacturedonthisKirkstallRoadsiteforover100years.FromthissiteSFSintecLtdcanofferarchitects,designers,consultingengineersandcladdingenvelopecontractorsaprovencommitmenttoproductquality,soundtechnicalsolutionsandefficientservice.

Commitment to investment and innovationTheSFSGrouphasaphilosophyofgrowingitsbusinessbyitscommitmenttoreinvesting,toensurestate-of-the-artfacilitiesand,throughitsextensiveresearchanddevelopmentdepartment,tocontinualinnovationofnewproductsandservices.

Industry associations SFSintecisactivelyrepresentedonthetechnicalcommitteesoftheleadingroofingandcladdingassociationswhoseektoencouragebestpracticeandconformancetoallrelevantregulations.

Globalmanufacturing

Globalsales&marketing


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Sectio

n 1Intro

ductio

nIntroduction

Section 1 IntroductionThespecificationofthefastener,despitebeingsuchasmallcomponent,iscriticaltotheperformanceoftheroofingandcladdingsystem.Thefastenerworksinclosecombinationwithsealingproducts,thereforethespecificationofthefastenerandsealingproductsneedtobeaddressedattheearlystagesofdetaildesignoftheprojecttoenablethecompletedenvelopetoperformitsrequiredfunctionthroughoutthefulltermofthesystem’sserviceanddesignlife.

1.1 Performance criteriaThisguideaddressestheprincipleperformancecriteriaoffastenersandsealants,namely;• Durability (corrosion resistance)• Weathersealing• The “Part L” issues of airsealing and thermal bridging• Aesthetics• Technical performance

Eachparticularapplicationwillneedthevariousproductstocomplywithatleastthreeofthesecriteriaandoften,aswithexternallyexposedfasteners,willrequireallfive.Failureoftheproductstosatisfythesecriteriamayleadtotheinevitable,andsometimescatastrophic,failureofthesystemor,attheveryleast,costlyremedialworks,sometimesevenbeforetheprojectcanbehandedovertotheClient.

Thisguidewillgiveyouthekeyinformationneededforyoutospecifyfastenersandassociatedsealstominimizetheriskofsystemfailure.

1.2a Industry associations Theguidancegiveninthisdocumentisgenerallyconsistentwithpublicationslistedbelowfromtheseassociations,aswellasthatgivenwithinBS5427:Part1:1996-thecodeofpracticefortheuseofprofiledsheetforroofandwallcladdingonbuildings.

NFRC -TheNationalFederationofRoofingContractorsAguidetogoodpractice,ThirdEdition1999andsubsequentTechnicalBulletins

• The Rainscreen Association

MCRMA -TheMetalCladdingandRoofingManufacturersAssociationDesignGuides&TechnicalPapers

EPIC-EngineeredPanelsInConstruction

SPRA-TheSinglePlyRoofingAssociationSingleply-CodeofPractice


1.2b Partnerships with leading system suppliersSFSintecalsoworkcloselywithmanyoftheUK’sleadingmanufacturersofroofandcladdingmaterialskeepinguptodatewiththeirdevelopmentsand,inpartnershipwiththem,seekingwaystoproducemoreefficientfasteningandsealingsolutionsfortheirsystems.

1.3 Examples of recent innovations

1.3a Development with Kalzip Ltd DevelopmentofSL3“thicktothin”selfdrillingfastenersforsafeandsecurefixingoftophatsectionstothinmetaldecks.

1.3b Development with single ply manufacturers including the Sika GroupDevelopmentofisoweld®-arevolutionaryheat-inductionweldingsystemforthesecurementofsingleplymembranesinafieldpatternratherthanin-seam.

1.3c Development with Kingspan Insulated PanelsDevelopmentofaself-coringfastenertoeliminatetimeconsumingprecoringandbackfillingontheirTopdekpre-engineeredinsulatedroofmembranesystem.

Introduction


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Section 2 Durability (corrosion resistance)• Definition-“likelytolast”,“remainingusefulforlongperiods”,“resistingwearanddecay”Ref;Oxford Dictionary

2.1 The problemIftheinstallerisallowedtousecarbonsteelfastenersfortheexternalenvelope,theinevitablecorrosionbroughtaboutbyexposuretotheelementswillresultinanumberofproblems;iftheseareleftunattendedthenultimatefailureofthesystemisaveryrealpossibility.

2.1a Problems due to corrosion of the head and washer• Stainingofthecladding

• Reductioninpulloverperformance

• Potentialleakageinto/throughthesystem

• Increasedmaintenanceandremedialwork

2.1b Problems due to corrosion of the shank• Reductionintensileperformance

• Reductioninshearperformance

• Reductioninpulloutvalues

• Stainingtointeriorsurfaces

2.1c Problems due to hidden corrosionWhilstcorrosionofexposedheadsontheexternalfaceofthebuildingandcorrosionofthevisibleshankinsidethebuildingarebotheasilyidentified,whatisconsideredamuchgreaterstructuralandsecurityriskisthatofcorrosionwithintheroofingorcladdingsystem.Thiswouldnotbevisibleandwouldonlymanifestitselfuponultimatefailureofthefastener,whichwouldresultinpartial,andpotentiallytotal,detachmentofthesystem.

Totalerosionofacarbonsteelfastenershank.Notethatthisproductwasoriginallymanufacturedwithastainlesssteelcapformedoverthehead,whichhasnotcorrodedtothesameextent.Thecorrodedportionwasbehindtheweathersheetandnotexposedtotheelements.

Sectio

n 2D

urability

Durability (corrosion resistance)


2.2 Fastener materialsThreadedfastenersforroofingandcladdingsystemsareavailableinthemarketplacemostcommonlyintwomaterials,coatedcarbonsteelandstainlesssteel.

Aluminiumthreadedfastenersarealsoavailable,howevertheirrangeofapplicationisgenerallyrestrictedtosecuringaluminiumprofilestotimbersupportsandlimitedapplicationsofaluminiumtoaluminium.

2.2a Coated carbon steelCarbonsteelrapidlycorrodesonexposuretohumidity.Fastenersinthismaterialaresuppliedwithsomeformofprotectivecoating,typicallymetallicororganic,oracombinationofthetwo.Cadmiumhasinthepastalsobeenusedasaprotectivecoatingbysomefastenermanufacturers.However,thisisacontrolledsubstancethatishazardoustohealthandthereforereputablemanufacturerswhooperaterecognisedQualityandEnvironmentalManagementSystems,aswellasenforcingHealthandSafetyProcedures,nolongerusecadmiumasaprotectivecoatingonthreadedfasteners.

CR6andCR3coatings

Hexavalentchromate[CR6]finishesonzincplateditemsarealsohazardousandarenowbannedinsomeareasofindustryacrosstheEU.Trivalentchromatefinishes[CR3]arestillusedinthefastenerindustrybutSFShavenotusedthemforsometime.

2.2b Stainless steelForincreaseddurability(corrosionresistance),fastenersarealsomanufacturedinvariousgradesofstainlesssteel.

TherelativemeritsofthesegradesarediscussedingreaterdetailinSection2.4

OverthefollowingparagraphsinSection2.3thisguidewillexplainthelimitationsofcoatedcarbonsteelandthetypesof“stainless”steelsappropriatetoroofingandcladdingfasteners.Wewillalsoexaminethedifferentaspectsthatshouldbeconsideredinorderthatthechoice,appropriatetotheproject,canbemadebetweencoatedcarbonor“stainless”steel.

AsfortheUKconstructionindustryhasnowmovedtomandatoryCEmarkingofbuildingmaterialsfrom2013,SFSnowusesthemethodologyfoundinEN12944forassessingbuildingdurability.EN12944istheEuropeanstandardandhasadetailedtableofexposurecategories.BS7543:2015canalsobeusedforassessingthedurabilityofthebuildinganditscomponents.


CorrosionofcoatedcarbonsteelunderKesternichtesting

Austeniticstainlesssteelfasteners


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2.3 Limitations of coated carbon steel

2.3a• Uncoatedcarbon steel rapidly corrodesuponexposuretohumidity

andpollutedenvironments

• Surfacecoatingswithexcellentcorrosionresistancecanbeappliedtoprolongafastener’slifebuttheywillonly slow down the corrosionprocess

• Theeffectivenessofthesecoatingscanonlybegaugedafterconsideringtheconditionof the coating once the fastener has been appliedwithintheconstruction

• Thesecorrosionresistantsurfacecoatingstendtohavepoor abrasion resistance

2.3b Pitched roofing and cladding systemsCoatingsonfastenerswithinmosttypesofmetalpitchedroofingandcladdingsystemswillinevitablysufferdamage 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 summary Will 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



2.4 Types of stainless steel“Rusting”isregardedbymanyasaprocesswhichisnotapplicabletostainlesssteel-thisishoweverincorrect.“Stainless”steelisagenerictermcoveringover200differenttypesofalloywhichall,tovaryingdegrees,stain-lessthancarbonsteel.Stainlesssteelscanbeclassifiedintothreemaingroups;

Austenitic, Ferritic and Martensitic.

2.4a Austenitic stainless steel• OnlygradesconformingtoBS5427:1996(seenote1)• Containsatleast17%chromium• Containsatleast8%nickel• Molybdenummaybeaddedforenhancedcorrosionresistance• Non-hardenable(seenote2)• Non-magnetic(seenote3)• Lowthermalconductivity;25%ofcarbonandmartensiticstainlesssteel• Bestknowngradesare304and316• Excellentcorrosionresistance(seenote4)

These characteristics make austenitic stainless steels the only suitable type for selfdrilling/threadforming fasteners for roofing and cladding.NoteBSEN10088-2hasintroducedarevisedsteelcodingsystem;theoldgradeAustenitic304isnow1.4301andAusteniticgrade316isnow1.4401.Specialhighperformancegrade1.4547hashighMolybdenumcontentforextraresistancetoChlorideattack.[seenote4]

2.4b Ferritic• Containsatleast12%chromium• Lowerductilitythanmartensiticsandaustenitics• Cannotbehardened• Susceptibletobrittleness

These characteristics make ferritic stainless steels unsuitable for the manufacture of selfdrilling/threadforming fasteners for roofing and cladding.

2.4c Martensitic• Containstheminimumchromiumcontentof11%• Poorcorrosionresistance• Susceptibletostresscorrosion• Canbehardened(attheexpenseoffurtherstresscorrosionrisk)• Highthermalconductivity(similartocarbonsteel)• Magnetic• Modifiedformsavailablebutstresscorrosionconsideredtoogreatarisk

(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.Wherefastenersareusedforstructuralorsafetycriticalapplications,measuresshouldbetakentoensurethatasoundandreliablevapourbarrierisinplacetopreventChlorinerichcondensationfromreachingthefastenersinquestion.Wherethisisnotpractical,thenalternativefastenermaterialssuchasaluminiumorAusteniticstainlesssteelgrade1.4547shouldbeconsidered.


SFS316austeniticstainlessselfdriller

HarryBrearley(1871-1948)-creditedwiththeinventionof“rustlesssteel”in1913atSheffield


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2.4 Other types of “stainless” fastenersBecauseofthehightechnologicalinvestmentrequiredforthemanufactureofbi-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 brittlenessHowever,real-lifeexposuretestsinanumberofenvironmentalconditionshaveshownthistypeoffastenermaterialtobesubjecttostresscorrosionandbrittleness-thiswouldn’thavebeenevidentunderKesternichandSaltspraytesting.Thistypeofbrittlecorrosionisinherentinthehardmaterialandisnotnecessarilyvisibletothenakedeye.

AsaresultofextensiveresearchworkcarriedoutbycorrosionexpertsinGermany,SwedenandtheUKonthistypeofmaterial,SFSintechavebeenadvisedthattherisksassociatedwithmodifiedmartensiticfastenersforroofingandcladdingaresignificantandthereforewecontinuetocomplywithindustryguidelinesandStandardsbymanufacturingstainlesssteelselfdrillersfromausteniticgradesusingthetriedandtested‘bi-metal’format.

2.4 Keynote summaryAustenitic stainless steel fasteners, such as grade 316, have been proven over a period exceeding 40 years 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.

Corrosionofnitridedstainless

Non-chromesurfacelayeronnitridedstainless

Brittlefailureofmodifiedmartensiticstainless

Stresscracksinmodifiedmartensiticstainless



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.



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2.5a System materials2.5a i) Envelope systemsCompatibilitywiththesheet/systemmaterialaswellasthepurlin/railwillinfluencethechoicebetweencoatedcarbonsteelorausteniticstainlesssteelfasteners.Typicalmaterialsforthesystemandsupportmayinclude;• Stainlesssteel• Coatedmildsteel• Aluminium• Fibrecement• Cementitiousboards• Highpressurelaminates• “Plastics”-GRP,polycarbonatesandPVC• Timber

2.5a ii) Flat roofing systemsItisgenerallythecompatibilityofthedeckthathasadirectinfluenceonthechoicebetweencoatedcarbonsteelorausteniticstainlesssteelfasteners.Decktypesinclude;• Coated(galvanized)steel• Aluminium• Timber• “Concrete”

2.5a iii) Cautionary notesRefurbishment over existing roof coverings -generallyflatroofing.Theinsulationtypewithinflatroofingdoesn’tgenerallyinfluencethefastenermaterial,however,onrefurbishment,wheretheexistinginsulationandweatherproofingistoremain,itistheconditionratherthantypeoftheexistingbuildupwhichwillinfluencethefastenermaterialchoice.Ifthereisdampnesswithintheexistingbuildupitwouldbeprudenttouseausteniticstainlessfasteners.Phenolicfoaminsulationwasusedonaverysmallnumberofflatroofprojectssomeyearsago.Ifitispresentbeneathaleakingroof,corrosionofgalvanisedmetalcomponentswithinthebuildupmayoccurasaggressivechemicalscanleachoutofthefoamboard.Contact SFS technical department for further information.

Only grade 1.4401 [316 Grade] stainless steel fasteners should be used to fix through Phenolic foam insulation boards.

2.5a Keynote summaryIthasalwaysbeengoodindustrypracticetouseausteniticstainlesssteelfastenersincombinationwithaluminiumandstainlesssteelmaterialstoavoidbi-metallicreactions.However,therearemanyfactorsthatinformtheselectionofthefastenermaterialinotherapplications.UsingtheexposureguidancegiveninBSEN12944[seesection2.6],higherperforminggradessuchas1.4401[316grade]and1.4547[A5grade]shouldbeactivelyencouragedwheretheservicelifeoftheenvelope/waterproofingmaterialisexpectedtoexceed20years.


“Old”rooftobeoverlaid


2.5b Design life requirementsTheclientordesignershouldspecifytheintendeddesignlifeoftheproposedbuildinganditsindividualbuildingelements,productsandcomponents.Referencemaybemadetothe2015revisededitionofBS7543.Asaguide,wegivebelowourinterpretationofextractsofBS7543:2015relativetofastenersaspartoftheroofingandcladdingenvelope.

Theclientshoulddefinethedesignlifeofthebuildingintheinitialbrief,whichshouldreflecttheoverallrequirements.DesignlifecategoriesforpartsaregiveninTable1andcategoriesforeffectsoffailurearegiveninTable2.Inadditiontheclientmightwishtospecifythedesignlifeforspecificassets,forexample,thefasteners.AnexampleofreferenceservicelivesforspecificcomponentsisgiveninAnnexDofthestandard.

Table 1 - Categories of design life

Category

Description

Life

Short-term Shorterlifethanthebuildingandreadilyreplaceable

Replaceable Shorterlifethanthebuildingandreplacementcanbeenvisagedatdesignstage

Maintainable Lasts,withperiodictreatment,forthelifeofthebuilding

Lifelong Lastsforthelifeofthebuilding

OtherthanShort-termbuildings,typically10yeardesignlife,carbonsteelfastenersarenotconsideredsuitable.

Thisflowchartbelow,Figure3fromBS7543:2015,asksthequestionsaboutaccessibilityofcomponentsandalsowhethertheycanbemaintainedorreplaced.Ifnot,thenthedesignhastobebasedonlastingthelifeofthebuilding,or,asinthecaseoffasteners,thelifeofthematerialtheyarefastening.Figure 3 - Decision process in support of categorization of design life (offasteners)

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

BSIStandardsPublicationBS7543:2015



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2.5b ii) Question: Can fasteners and cladding envelopesealants be classed as “maintainable” ?Asnotedabove,non-exposedfastenersandsealscanonlybeaccessedbyremovaloftheexternalweatheringsheet.Exposedfastenersmay,intheory,havetheirvisibleparts“recoated”butthisshouldnotberegardedasacceptableatthedesignstageofaproject.Furthermore,applyinganewcorrosionprotectivecoatingtothevisiblehead,providinganappropriatepretreatmentcanbecarriedout,aswellasbeing,inmostcases,aestheticallyunacceptable,wouldnotreinstatecorrosionprotectiontotheconcealedshankwhichmayalsobesufferingfromcorrosion.Answer-Fastenersandsealingproductsarenotclassedasmaintainable

Table 2 - Categories of effects of failure

Category Effect Life

A Dangertolife(orinjury) Suddencollapseofstructure

B Riskofinjury Loosestairnosing

C Dangertohealth Seriousdamppenetration

D Costlyrepair Extensivescaffoldrequired.Durabilitycriticalcomponentfailure(seenotebelow)

E Costlybecauserepeated Windowfasteningreplacement

F Interruptiontobuildinguse Heatingfailure

G Securitycompromised Brokendoorlatch

H Noexceptionproblems Replacementoflightfittings

Note - Individual failures can be in two or more categories.

Manyofthebuildingswherefastenersareusedtosecuretheroofingandcladdingenvelopehavedesignserviceliferequirementsintherangeof25to60yearsand,asthefastenersarepotentiallyofrelativelyhighrisk,typicallycategoryA,B,CorDasdefinedintable2above,andtheyarenotconsideredreplaceableormaintainable,theywouldneedtobedesignedtobelifelongastable1(totheservicelifeoftheroofing/claddingsystem)

2.5b Keynote summaryCoated carbon steel fastenersshouldbeconsideredonlyforshortlife,temporarybuildingsandthoseincategoryC1intheEN12944tableshownin2.6,page17ofthisGuide.

Forallotherapplications,Austenitic stainless steel fasteners in Grade A2 or A4isthepreferredchoiceforallotherbuildings-specifiersshouldselecttheappropriategradetosuittheexpectedexposureandservicelifeusingthetableabove

Weatherandairsealingproductsshouldmatchthedesignlifeoftheroofingorcladdingsystemandtheappropriatefastenermaterial.


Fastenerscanbeclassedas”highrisk”-CategoriesA-D


2.5c External environmentTypicalUKatmospheresmaybedividedasinthefollowingtablewhichshouldbeconsideredtogetherwiththeBSEN12944tableinsection2.5b:

Inadditiontotheclimaticconditionspresentduringeachseason,thelocalatmosphericconditionsintheimmediatevicinityofthebuildingarecriticalintheselectionofcoatedcarbonorausteniticstainlesssteelfasteners.

Typical atmospheres may be divided as in the following table;

Marine C5-M Upto2kmfromthesea.Highlevelsofchlorides

CoastalC4 Between2kmand10kmfromthesea BS7543:2015ClauseA.1.3Coastalregions; Seafogsormistsmightalsolingerwithinseveralmiles ofcoasts.Particularconsiderationshouldbegivento wind-blownsaltatmosphereandhowfarinlandthiswill impactthedesignspecification.

Industrial C5-I Atmosphereheavilypollutedbysulphurdioxideandother pollutants,typicallynitricoxides,chlorine,hydrogenchloride, formicacid,aceticacid,allinthevicinityofcorresponding industrialplants.

Urban C3 Denselypopulatedandpollutedbysulphurdioxide,also propertiesadjoiningbusymotorwayjunctionsorelevated sectionswhichcanbeexposedtoroadsaltsprayinwinter.

Rural C2 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 fastenerswouldcorrodewhenexposedtoany

oftheseexternalenvironmentsandthecorrosionratewillincreaseasyoumoveupthetable.

• Austenitic stainless steel fastenersaredurableinalltheseexternalenvironmentsandshouldbespecifiedinmarineandcoastalenvironmentsand,inmanycases,wouldberecommendedinindustrialatmospheres.A4(316)gradeisparticularlyrecommendedforindustrialandcoastalregionswheredesignliferequirementexceed15-20years.

• Cladding envelope sealing productsspecificationsshouldalsobe

compatiblewiththedesignlifeofthesystemanditsfasteners.

Marine

Rural



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2.5d Internal environment / building useSomebuildinguses,andtheprocessestheyhouse,canpresentveryonerousinternalenvironmentalconditionsuponthefastenersandseals.Insuchcases,coatedcarbonsteelwouldnotbeconsideredanappropriatefastenermaterialchoice.

2.5d i) Building use - “at risk” categoriesDuetotheirgeneralfunctionandinternalconditions,austeniticstainlesssteelfastenersshouldbeconsideredonthefollowingbuildingcategories

• Leisureindustry…swimmingpools,sportscentres,stadia.

• Transportindustry…airportterminalsandbuildings,ferryanddocklandfacilities,railwaybuildings

• Waterindustry…sewageandwatertreatmentworks,pumpingstations

• Powerstations,wastetoenergyplants

• Manufacturing…paper,pharmaceuticals,chemicals,brick&masonryproducts,breweries,textiles,food&drink

2.5d ii) Building use - further “at risk” categoriesAdditionally,therearesomeotherbuildingcategorieswhich,eventhoughtheirinternalenvironmentmaybenon-aggressive,demandthatausteniticstainlessfastenersbeconsidered.Thepotentialforleakageresultingfromcorrosionofcoatedcarbonsteelmayresultindamagetoexpensive/sensitiveequipmentandcouldalsobeextremelydisruptivetotherunningofthebusiness.

• Hygiene,Foodprocessing

• Electronics,computerequipment

• Highvaluegoods

• Schools

• Hospitals

2.5d iii) Building use - lower risk categoriesTypicalbuildinguseswherecoatedcarbonsteelfastenershavebeenshowntoperformadequatelyforperiodsoffunctionallifeexpectancyupto25yearsandthereforewherecoatedcarbonsteelcouldbeconsideredinclude;

• Retail

• Distribution

• Manufacturingof“dry”goodssuchasassemblylines,windowsanddoors,automotiveproducts,whitegoodsetc.

2.5d Keynote summaryFromtheaboveitcanbeseenthattheinternalenvironment/buildingusehasamajorinfluenceonthechoiceoffastenermaterialandthatausteniticstainlesssteelshould,inmostinstances,bespecified.Specifyingausteniticstainlesswouldalsoeliminateanyfutureriskifthebuildingusechanges.



2.5e Project-based long term warranty requirementsThereisanincreasingdemandbyclientsandbuildingownersfortheperformanceofproductswithinthebuildingconstructionandenvelopetobewarranted.Theroofingandcladdingindustryhasrespondedtothesedemandsandvariouswarrantyschemesarenowavailable.

2.5e i) Industry association system basedWarrantiesareavailablethroughanumberofindustryassociations-somewarrantworkmanshipaswellasmaterials.Usuallyaninsurancepremiumisrequiredtobepaidwhichisapercentageoftheenvelopecontractvalue.

2.5e ii) System suppliers warranty schemesTheprinciplesystemsuppliermayoperatewarrantyschemesforthecompletesystem.Sotheycaneliminatetheriskofsystemfailureduetoancillaryproducts,theprinciplesystemsupplierwillspecifycomponentstobeusedinconjunctionwiththeirproductstomakeupatotalsystem.Warrantiesarethenobtainedfromtheirpartnersuppliersandinstallersandasingletotalsystemproject-specificwarrantyisthenpassedtotheclient.

Systemsupplierwarrantyschemesdonotnecessarilyrequireapolicypremiumtobepaidbytheclient.

SFSintecworkcloselywiththeleadingsystemsupplierswhospecifyfastenersandancillaryproductssuchassealantsappropriatetothewarrantyperiodrequired.

2.5e iii) Component suppliers warrantiesAsanalternativetothewarrantyschemesabove,theclient(throughthearchitect/designer)maywishtospecifyandobtainseparateindividualproductwarrantiesfromallthevarioussupplierswhosecomponentsareusedorspecifiedwithinthesystem,andalsotheinstallerifworkmanshipistobewarranted.

2.5e Keynote summaryProject-specific warrantyClientsshouldbeencouragedtoobtainwarrantieswhichareproject-specific,andoftenupto30years-andtheseshouldincludeallcomponentscriticaltothebuildingenvelope.Onlyausteniticstainlessfastenerswouldbedeemedtoprovidetherequiredlevelofperformance.

Beware,warrantiesshouldnotbelimitedtosimplysupplyingmoreproducts-theclientshouldseekthere-assurancethatthewarrantycovers“making good the roof”.Theclientshouldensurethesuppliertakesfullresponsibilitywithinthewarrantyoffered.

Products liability InsuranceThechoiceofsuppliershouldalsobelimitedbywhethertheirproductionplantsoperateQualityandEnvironmentalManagementSystemsandhavecertificationshowingconformanceto,forexample,ISO9001:2000andISO14001:1996.X

LInsurancecertificate

SFS

intecprojectwarranty

TataSteelPanelsandProfiles



17

2.6 Exposure and corrosion - selecting the correct productBSEN12944givesguidanceonvariousenvironmentalexposuresandassociatedcorrosionrisks.Theremaybetimesandlocationswheretheexposurecategoryishigherthanexpected.ForexamplealightingcolumnlocatedbyanelevatedmotorwaymightbeconsideredtobecategoryC3,butwhensubjectedtolocalconditionssuchaswintersaltspray,mightinfactbeexposedtocategoryC5-M.

Recommended fastener material to suit EN 12944 exposure categories

Thisrevisedandupdatedapplicationtablesimplifiestheselectionoftheappropriatefastenermaterial.

Warranted performanceStainlesssteeltype304austeniticfastenersarewarrantedforcategoryC1,C2,C3and,withpriorapproval,categoryC4.Stainlesssteeltype316iswarrantedforallapplicationsuptoandincludingC5-I,andwithpriorapproval,categoryC5-M.Stainlesssteeltype1.4547iswarrantedforanyswimmingpoolhallsandcertainchemicalprocessingplants.*priorapprovalisrequiredasapplicationsvaryfromprojecttoproject.Itisnotpossibletocoverallpossibilitiesindatasheetsandsoconsultationisrequired.Therefore,giventhecomplexchemistryinvolved,usersarestronglyadvisedtocontactSFStechnicaldepartmenttodiscussindividualprojectsintheC5-IandC5-Mcategories.Wewouldbepleasedtoadviseanddevelopspecificationstosuit.

Service lifeTherearemanyfactorsthataffecttheservicelifeofmetalproductsinconstructionprojects.Theservicelife,unlikethewarrantyperiod,isforguidanceonlyandisgenerallytakentobetheuseful,practicalworkinglifeofaproductasinstalled.Forfasteners,becausethereisnomaintenanceinterval[fastenersbeingconsideredtobeinaccessibleandnotserviceableoncefixed]theusefulservicelifewouldcometoanendwhen,forexample,

• thebuildingisdismantledoralterationsarecarriedoutwhichrequireremovaloftheweatherproofinglayer andassociatedfasteners

• thefixinghasfailedorissoheavilycorrodedthatmechanicalfailureisimminent

• deteriorationoftheweatherproofinglayerbecomestooextensivetoremainwindandweathertight

• weatherpenetrationoffastenersealingwashershasoccurredorairleakageissignificant.

Forcarbonsteelfasteners,servicelifeinaC1categorymaybeacceptable,perhaps15-20years,butthesameproductusedinsaycategoryC3mightstarttosuffercorrosionwithin12monthsofinstallationandbeattheendoflifeandreadyforreplacementinlessthan7years.InC4conditions,corrosionmightberapid,withfailurewithin5years.

Poorworkmanship,incorrectproductselection,adverseweatherconditions,exposuretoindustrialoratmosphericpollutants,distancefromthesea,winterroad-saltsprayfromadjoiningbusyroads,accidentaldamage,alterationstothebuilding,highinternaltemperaturesorhumiditylevels,interstitialcondensation,highradiationlevelsandincompatiblemetalcomponentswillallaffecttheservicelifeofthecomponent.

Constructionprofessionalsmustselectanappropriatefastenermaterialthatwillmatchtherequiredservicelife,warrantyperiodandbuildingfabriclifegiventheexposurecategorythatisanticipated.SpeculativebuildingprojectsshouldbeconsideredtobecategoryC3asaminimumsinceoccupiersofrentedbuildingsmaybefromanyindustryandtheimpactoftheirproductionprocessesonthefabricwillbeentirelyunpredictable.

Corrosivity Category C1-verylow C2-Low C3-Medium C4-High C5-I-Veryhigh

(industrial)C5-M-Veryhigh(Marine)

Swimming Pools& Chemical Plants

Examplesoftypical

environmentsina

temperateclimate

(informativeonly)

Interior-Heatedbuildingswith

cleanatmosphere

Ruralareas-lowlevelsofpollution

-Unheatedbuildingswhere

condensationmayoccur

Urbanandindustrialareas

moderatepollutionCoastalarea

withlowsalinity-Productionroomswithhighhumidity

andsomeairpollution

Industrialandcoastalareaswithmoderatesalinity

Industrialareaswithhighhumidityandaggressiveatmosphere.Permanent

condensationandhighpollution

Coastalandoffshoreareaswithhighsalinity

Permanentcondensationandhighpollution

Withinpoolhallsand

certainchemicalprocessing

plants-fastenersthatpenetrateorarebelowvclandexposedtochlorinevapour

A5 1.4547Max Warranty

✔40+

✔40+

✔40+

✔35

✔25

✔25

✔20

A4 - 316 1.4401Max Warranty

✔40+

✔40+

✔40

✔30

✔20

✘✔15

✘-

A2 - 304 1.4301Max Warranty

✔30

✔25

✔20

✘✔15

✘✔10

✘-

✘-

KEY✔ ✔ ✘✔ ✘

Suitable but not economic Recommended Requires approval Not suitable

Popular Name

EN Name



APPLICATION DESCRIPTION CODE FASTENER


SX3/9-L12-S19-6.0 x 29 x A4 (x colour if applicable)

(x colour if applicable)

SX14/12-L12-S19-5.5 x 40 x A4

SL2-S-L12-S14-6.3 x 28 x A4 x colour

SXC5-S19-5.5 x Length x A4 x colour


SL2-S-S16-6.3 x 28 x A4 x colour

SDK2-S-377-6.0 x 35/45

SDK3-S-377-6.0 x 35/45

SL3/2-5-S-SV16-6 x 27 x A4

SX2/18-A16 5.8 x 38SX2/28-A16-5.8 x 48

SX3/9-S16-6.0 x 29 x A4

SX14/12-S16-5.5 x 40 x A4

SL2-S-S14-5.5 x 27 x A4

Telescope tube R75 x length fastener BS-S-4,8 x length Telescope tube R45 x length fastener BS-S-4,8 x length

m1tr- M8, M10 or M12 x Length

MBRK-S4-H18-10 x Length

SX-S16 x Length x A4

SX3/15-D12-5,5 x 30 x colour

SLA5/4-6-S4-6.0 x 19

SFS

TSFS

T

20

1617

SFS

TSFS

T

20

18

Drillerforcoldrolledsteelwithirius®powdercoatedcolouredheadwherevisible.

Drillerforhotrolledsteelwithirius®head.

Drillerforclamping/stitchingwithirius®powdercoatedcolouredheadwherevisible.

Drillerforinsulatedpanelstocoldrolledsteelwithpowdercoatedcolouredhead.

Drillerforinsulatedpanelstohotrolledsteelwithpowdercoatedcolouredhead.

Drillerforclamping/stitchingwithpowdercoatedcolouredhead.

Drillerforsecuringstandingseamsystemhalterstodeckswithspecialdrivesystemtoeliminateovertorque.

Drillerforsecuringstandingseamsystemhalterstocoldrolledpurlins/tophatswithspecialdrivesystemtoeliminateovertorque.

Drillerforsecuringstandingseamsystemhalterstocoldrolledpurlins/tophatswithhexagonalhead.

Drillerforsecuringtophatspacertosteellinerdeck.

1

2

3

4

5

6

7

8

9

10

10

Site assembled liner panel systems.

Insulated panel systems.

Aluminium standing seam 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*,allfastenersshownaremanufacturedfrom316seriesausteniticstainlesssteel.TherearemanyothertypesavailableandSFSintecwillbepleasedtogiveadviceonspecificapplicationsonthecontactdetailsbelowore-mailingdetails/[email protected]



19



SX3/9-L12-S19-6.0 x 29 x A4 (x colour if applicable)

(x colour if applicable)

SX14/12-L12-S19-5.5 x 40 x A4

SL2-S-L12-S14-6.3 x 28 x A4 x colour



SL2-S-S16-6.3 x 28 x A4 x colour

SDK2-S-377-6.0 x 35/45

SDK3-S-377-6.0 x 35/45

SL3/2-5-S-SV16-6 x 27 x A4

SX2/18-A16 5.8 x 38SX2/28-A16-5.8 x 48

SX3/9-S16-6.0 x 29 x A4

SX14/12-S16-5.5 x 40 x A4

SL2-S-S14-5.5 x 27 x A4

Telescope tube R75 x length fastener BS-S-4,8 x length Telescope tube R45 x length fastener BS-S-4,8 x length

m1tr- M8, M10 or M12 x Length

MBRK-S4-H18-10 x Length

SX-S16 x Length x A4

SX3/15-D12-5,5 x 30 x colour

SLA5/4-6-S4-6.0 x 19

SFS

TSFS

T

20

1617

SFS

TSFS

T

20

18

Drillerforsecuringmetaldeckingtocoldrolledpurlinswithhexagonalhead.

Drillerforsecuringmetaldeckingtohotrolledpurlinswithhexagonalhead.

Drillerforclamping/stitchingdecksidelapswithhexagonalhead.

Thermallybrokenfasteningsystemforinsulationtometaldeck,comprisingofafastenerinstalledthroughapolyamide“telescopetube”.

Thermallybrokenfasteningsystemforinseamfasteningofsingleplymembranesthroughinsulationtometaldeck,comprisingofafastenerinstalledthroughapolyamide“telescopetube”.

316austeniticsteelthroughboltforsecuringrainscreenbracketrytoconcretesubstrate.

Selfdrillerforsecuringverticalaluminiumrailstoaluminiumbrackets.

Selfdrillerforsecuringaluminiumrainscreenpanelstoaluminiumrailsandframeworkover2.5mmthicknesswithpowdercoatedlowprofilecolouredhead.

Nylonplugand316austeniticscrewforthroughfixingbracketrytoconcrete/masonrysubstrates.

Drillerforbracket,thermalpad,boardlinerintosteelframingsystem.

11

12

13

14

15

18

17

19

20

1514

13

12

11

Single ply membrane over insulationon metal deck.

Rainscreens - Bracket to steel framing

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+ Pink Strip sealants for metal

roofing and cladding

Rainscreens - Rail to bracket

Rainscreens - Panel to rail

16

19

20



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.

Loosesealingelementnotretainedunderhead

PoorqualityEPDMshowingUVdegradation

Weathersealing


21

Sectio

n 3W

eathersealing

3.2 The sealing washer solutionLong-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,forexamplewhereasthenormalhardnessis70/80shore,onclampingandinsulatedpanelfastenersamuchsofterEPDMwithahighrecoveryfromcompressionvalue(70%)isused,referto3.3a&b.

3.2b Metal backingToensuretheEPDMcompressesevenlyandformsasealagainstboththesheetandthefastenershank,theEPDMshouldbevulcanizedtoametalbackingwasher.Merelyglueing,asisthepracticeofsomemanufacturers,wouldpresentariskoftheEPDMdelaminating.Theproblemwithloosesealingelementsisclearlyillustratedonthepreviouspagewhere,foranumberofreasonsassociatedwithpoorfastenerdesign,thesealingelementhas“extruded”beyondtheheadofthefastenerandhasbeendestroyedwiththeresultthatthesealwillnolongerbeeffective.

3.2c DiametersSealingwashersareavailableinawiderangeofdiametersfrom,typically,12mmto29mm.

Forprimaryvalleyfixingofthrough-fixedmetalroofweathersheetsandinsulatedroofpanels,19mmisusuallythepreferreddiameter.

For“plastics”rooflightprofiles-typicallyGRPandpolycarbonate,largerdiameterwashers,typically29mm,orinsomeinstancescrownsaddlewashers,arerecommended.

Forwallingsystemsandsecondary(clamping)fasteners,smallerdiameters,typically12mm-16mm,areused.

19mm&29mm

12mm&16mm

Weathersealing


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”.Theloweronesthreadformintothepurlinandaretypically5.5mmminimumdiameter.Attheheadandwasherendofthefastenerthereisatopthreadsectionofanincreaseddiameterdesignedtosupporttheouterskinofthepanelandthusimpartpermanentcompressionofthewasher.

Top thread performanceThishastobedesignedtoaccommodateallpositiveloadingconditions,includingconcentratedfootloads,whilstmaintainingoptimumpulloverperformanceofthewashers.Insulatedpanelfastenersshouldbedesignedwithatopthreadwiththisoverallperformancerequirementinmind.Thismaybebyhavingatopthreadofc7mmdiameteror,ifless,thenthethreadformdesignsshouldprovidetherequiredsupport.Manyalternativesuppliershavetopthreadsofpoordesignwhichareunabletoaccommodatealltheseloadingsandthereforethesupportgivenwillinevitablybereducedthusleadingtoaweathersealrisk.

Thread-free sectionForoptimumperformance,designsshouldalsoincorporateathread-freefeatureimmediatelybehindandbelowthewasheroninsulatedpanelfasteners.ThisenablestheweatherskintobepermanentlysupportedthuscompressingtheEPDMwasher.Thiscompressionandsealwillbemaintainedeveninconditionswherethefastenerisusedtodrawthepanelbacktothesupportorwherefastenersareoverdriven.Alternativedesignswithtopthreadsextendingrightuptotheheadpresentamajorriskinboththeseconditions.

3.3b Clamping fasteners to ensure weathersealingClampingfastenersarepurpose-designedtoclampthinmaterialstogether(e.g.sidelapsofprofiledmetalsheets)andforfixingflashingsandclosurestoprofiledmetalsheetsandtothemselves.Useofinappropriatefastenersmayleadtoovertorqueinwhichcase,notonlyisweatherandairtightnesscompromised,butalsothestructuralperformanceofthefastenerislostandcomponentsmaybecomedetached.Clampingfastenersshouldincorporatefeaturestoensurestructuralperformanceandweathertightness.

• Reduced diameter drillpoint-highpulloutandclampingforces• WRS washer-thickerandsofterwithahighrecoveryfromcompressionvalue(70%)toensure

asealoverarangeofapplicationthinnesses.• Thread free (free spin) zone-todrawandclampthematerialstogetherandtoeliminateany

weatherandairtightnessriskassociatedwithover-driving.

3.3c Specialist fasteners designed to prevent overdrivingOverdrivingfastenersintothin[<1mm]steelsheetisanincreasingproblemasbuildingdesignersselecteverthinnersheetmaterialforstructuralapplications.Typicalsitelabour’spracticeistoremovedepthcontroldevicesfrompoweredscrewdrivers.Thisleavestheinstallerwithlittlecontroloverthesettingofthefastener,whichhappensveryrapidlywhenitisbeingdriveninatmorethan1000rpm.Overdrivingcrushesthesealingwashersoreducingthewatertightsealandwilleasilystripthethreadforminsteeluptoabout2mmthick,leadingtoimmediatefixingfailure.Inthickersteels,thegripofthethreadisnotdamaged,butthehightorqueimpartedtothefastenerwillresultinveryhighresidualtensilestresses.Overdrivingisthemostcommoninstallationfaultobservedintheworkplaceandiscausedbylackoftrainingandabeliefin“thetighterthebetter”.Totrytoovercomethisfixingissue,SFShaveengineeredarangeofproductsspecificallydesignedtopreventoverdriving.Thethreadfreezonementionedaboveisonesuchmeasure;othersinclude:

• SDKandSOLfasteners,whichfeatureadrivepinthatbreaksoffatapresenttorque

• SL3“thicktothin”fastenersdesignedtoclampthicktophatsectionstothinmetaldecksusingacombinationofaspecialsprungwasher,deepthreadsandafreespinzone

• Irius®underheaddrivesystem

• TUSsystemforrainscreenpanels

Insulatedpanelfasteners

Clampingfastener

Weathersealing


23

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%.

4.1c October 2010 Part AD-L2 England and Wales Technical Standard J [Scotland] - Overview The2010ApprovedDocumentsandRegulationsaresimilartothe2006version,howevertherearemanychangestotheiSBEMsoftwarewhichmodelstheCO2outputofthebuilding.Mostnotableare:*Usingarangeofnotionalbuildingstomodelvarioustypesofusage[previously‘onesizefitsall’]andvaryingtheCO2reductionlevelstosuitthenotionalbuildingtypesratherthanablanketreduction*Ashiftto3differentlightinglayoutsfornaturallightsituations-sidelit,overheadlitandnolightapplications*Retainingthe2006Uvaluelevelsas‘back-stop’levels*Focusonreducingcoldbridgingbyaddingpenaltiesforpoordesignofdetails*Overallacombinedreductionofabout27%intheallowableCO2leveloverthe2006level

TheiSBEMcalculationnowhasbesubmittedattheplanningstageandconfirmedwith

an‘asbuilt’calculationattheendoftheproject.

What impact will these changes make on the external cladding envelope?- U-values -Itisgenerallyfeltthat,withthenewcalculationmethodologyforthebuildingsCO2emissions,afurtherreductioninU-values(ie.increasinginsulationthicknesses)ofthecladdingenvelopewillonlyhaveminimaladditionalpracticalimpactonthebuildingsenergyefficiencyoverthechangesalreadyimplementedin2002.

- Natural lighting -Oncertaintypesofbuilding,theprovisionofnaturalrooflightingmayallowareductionintheusageofelectriclightingthusmakingsignificantcontributionstothebuildingsenergyefficiency.ThiswillusuallymorethancompensateforthehigherU-valuesnormallyassociatedwiththerooflightelementoftheroof.

- Cold bridging-Elimination/reductioninthermalbridgeswillremainanimportantdesignconsiderationatjunctions,interfacesandfasteners.

- Air-tightness-Increasingair-tightnessfromthe2002levelsof10m3/sqm/hrwillgenerallyshowagreaterbenefitandafurtherincreaseinair-tightnessmaybechosenbythedesignerasasignificantcontributoryfactortocompliancetotheBuildingRegulations.

The2010revisiontoPartL2Arequiresallowableairleakageratestohalveto5m3/m2/hour.ThischangewillbringsignificantCO2reductionstotypicalindustrialtypebuilding-industrystudieshaveshownreductionsintheregionof3to4kGsofCO2/m2whenmeasuredagainstthebenchmark2002specificationusingasimpleindustrialunitlayout.

Sectio

n 4T

he “Part L” issue

The “Part L” issue - Airsealing and thermal bridging


4.2 Elimination of cold bridges by using thermally broken fastenersForsingleplymembraneroofingsystems,boththeinsulationandthemembranemaybemechanicallyfixed.PartL2A,withits’increasingfocusonreducingcoldbridging,hasledSFSintectointroducearangeofthermallyisolatedfastenersforthesepopularroofingsystems.Becausethemetallicfastenerelementislocateddeepwithintheinsulationlayer,heatflowsaresignificantlyreducedovertheoldstylemetalplateandscrewapproach.

Asthemarketleader,SFSintec’sISOTAKsystemoffersawideselectionoftelescopictubesandhighperformancefastenerstosuitanyapplicationincludingtimber,steelandconcretedecks.WorkinginpartnershipwithboththeinsulationandmembranemanufacturershasenabledSFSintectodevelopproductsthatofferveryhighlevelsofclampupforcetoresistwindloads,whilstreducingheatlossbysome10%ontypicalapplications.

4.3 Achieving airtightness with warranted sealants Generally,toachievetheserequiredlevelsofairtightness,additionalsealingmaterialshavetobeincludedwithinthesystem.Thesesealsareusuallyinstalledattheinnerliningpositioniebelowtheinsulation…thefollowingsection4.3givesfurtherinformationonthespecificationoftheseals.

TataSteelhavepublishedaTechnicalPaperentitled“Creatinganair-tightbuildingenvelopeColorcoat®TechnicalPaper-whichgivesfurtherusefulguidanceonachievingair-tightnessonbuilt-upandinsulatedpanelsystems.

Warranted sealantsThereareanumberofmechanicalandacceleratedtestsdevelopedbysealantmanufacturersforroofingandcladding.ThebasictestsdeemwhetherthesealsareclassedasTypeAorTypeB.TheNFRCpublishedTechnicalBulletin36whichgivesasummary.However,thereisaneedforthesealstobewarrantedforupto30yearsthusbeingcompatiblewiththeausteniticstainlessfastenersandsheetsystemasreferredtoinsection2.5.

SFSintecworkedcloselywithaleadingsealantmanufactureranddevelopedahighperformancebutylstripsealantrangeforprofiledroofingandwallingsystems.TheirperformanceunderallthemechanicalandacceleratedtestsexceededthebasicrequirementofaTypeAsealantsuchthatSFSintecareabletoissueawarrantyforupto30years.ThiswarrantedSFSintecsealantisreferredtoasTypeA+andiscolouredpinkforeaseofidentification.

Clamping fasteners (referto3.3b)Toensurethatthewarrantedsealantsperformeffectivelywithintheapplication,theyhavetoworkincombinationwiththepurposedesignedclampingfastenersdiscussedwithinsection3.3b.

ThreadfreezoneforweathertightclampingonSFSstitchingfasteners

Coldbridgingviaall-carbonsteelfasteners

The “Part L” issue - Airsealing and thermal bridging


25

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.

Sectio

n 5A

esthetics

UVfadingofmouldedheads

Pushfitcapacceleratingcorrosion

Aesthetics by design


5.2 Factory-coloured solutionsToaddressthemanyproblemsassociatedwithpush-fitcaps,SFSintechasdevelopedrangesofcolouredandaestheticallyshapedfasteningsystemswhichhaveevolvedwiththeintroductionofnewcladdingmaterialsandprofiles.Thesehavebeendesignedwiththedesiresofthespecifiers,contractorsandbuildingownerstakenintoconsideration.

5.2a The powder coated head solutionPowdercoatingoffersanumberofbenefits.Itistough,durableandaccuratelymatchesthecolourofthesurroundingweathersheet.ItisonlyveryslightlyaffectedbyUVlight,andsofadingorweatheringisuncommon.Thefastenerheadremainssmallandcompactandthereisnobulkyplastictocausevisualintrusion.

5.2b The “unobtrusive” solutionWherethedesignerselectsawallcladdingmaterialorprofileforitshighaestheticappeal,itmaybemoredesirablethatthefasteningsystemisunobtrusiveandblendsinwiththecladding.Somewallingsystemsaredesignedsuchthatthefastenersaretotallyconcealed,forexample,flatormicro-ribbedinsulatedwallpanelsareoftenfixedthroughtheir“tongue&groove”joint.

However,therearemanywallingsystemswhicharevisiblyfixedandtheraisedheadsoftraditionalmouldedheadedfasteners,eventhoughtheymayofferlongtermcolourmatching,maynotmeettheaestheticrequirements.

Lowprofilecolouredheadformshavebeendevelopedspecificallyforapplicationswherethefastenerhastofulfilallitsnormalstructuralrequirementswhilst,atthesametime,blendinunobtrusivelywiththecladding.

Theirius®headformmaybepowdercoatedforcolourmatchingpurposesandtheinnovativeunderheaddrivesystemenableseaseofinstallationwhilstalsoofferingahighleveloftamper-resistance-aestheticswithsecurity.

Irius®headform

UnobtrusiveIrius®atWalesMillenniumCentre

ColouredIrius®headform

Paintedheadform

Aesthetics by design


27

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 Safety & 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.ThisenablesthecalculationofthestandarddeviationandthecharacteristicvalueasassessedusingthemethodlaiddowninBSEN10204:2004.

6.1aTheSFSintecTechnicalValuedocumentspresenttestvaluesfordifferentfasteners.Whenpossible,theresultshavebeenevaluatedaccordingtotheEuropeanstandardsandrequirementsfortheCEmark.Fortheevaluation,theEuropeanOrganisationforTechnicalApprovals(EOTA)haspublishedaguideline1)“FasteningScrewsforMetalMembersandSheeting”.Hereisashortsummaryoftheguidelineregardingtheevaluationofcharacteristicvaluesandonecalculationexample.

Characteristic Value Rk of a Fastening Capacity

AcharacteristicvalueRkfortensionandshearresistanceofthefasteningiscalculatedaccordingtotheequation1. Rk =(Favg-k*s)*a (1) ,where Rkisthecharacteristicfasteningcapacity Favgistheaveragevalueoftheultimatefailureloads kisthestatisticalcoefficientaccordingtoasamplesizen sisthestandarddeviation aistheadjustmentcoefficientforthetestresults

Pullouttesting

Purpose-designeddrillpoints

Technical performanceS

ection 6

Technical


6.1a ContinuedTheadjustmentcoefficientcomesfromtheequation2.Thepurposeoftheadjustmentistoreduceeffectsofmaterialpropertydeviation.

a =(Rm,min/Rm,obs)*(tmin/tobs)≤1 (2) ,where Rm,ministheminimumtensilestrengthofarelevantproductstandard Rm,obsistheactualtensilestrengthofthetestspecimen tministheminimumthicknessaccordingtoarelevantproductstandard tobsistheactualthicknessofthetestspecimen

Statistical evaluation and k value

Thetestresultsareevaluatedaccordingtostatisticalmethods.Theresultsareassumedtofollowalog-normaldistribution.Fortheevaluationofa5%fractilevalueandaconfidencelevelof75%ischosenaccordingtotheEOTAguidelineandISO12491:19972).Table1showsthestatisticalfactorkaccordingtoasamplesizenormallyneededforthetests.

Table1.k-valuesforthesamplesizen.

n=samplesize n=6 n=10 n=12 n=20

kvalue 2,34 2,10 2,05 1,93

Note!Allcalculations,measurements,fastenersanddesignmethodshavetobeverifiedbyaresponsibledesigneroranengineer,regardingthecorrespondingstructureandload.Pleaseconsultyournationalnormsandapprovals.

6.2 Pullover resistanceThisistheabilityofthefastenertopreventthesheetmaterialfailingbypullingovertheheadofthefastener.

AsreferredtoinSection3onweathersealing,resistancetopulloverfailureofthesheetisinfluencedbythesheetmaterialthicknessandtensilestrengthincombinationwiththestrengthanddiameterofthewasher.

Thefastenersupplierspecifiedshouldbeabletoprovidetheengineerwithpublishedtestresultsofvariouswasherdiametersinvarioussheetmaterialsandthicknesses.

6.3 Concentrated foot loadingsThetwoprincipleapplicationswherefootloadingshavetobeconsideredinfastenerdesignaremetalfacedinsulatedroofpanelsandsingleplyroofmembranesoverinsulationboards.

Insulated roof panelsAsdescribedinSection3.3a,thetopthreadofinsulatedpanelfastenershastobedesignedsothatitwillcontinuetosupporttheexternalskinofthepanelagainsttheconcentrateddynamicloadsimpartedbyfoot-traffic.

Thismaybebyhavingatopthreadofc7mmdiameteror,ifless,thenthethreadformdesignsshouldprovidetherequiredsupport.Manyalternativesuppliershavetopthreadsofpoordesignwhichareunabletoaccommodatealltheseloadingsandthereforethesupportgivenwillinevitablybereducedthusleadingtoaweathersealrisk.

Thisenlargedthreadalsoworksincombinationwiththethread-freezone,whosefunctionisalsodescribedinSection3.3a,toensurebothawalkableandweathertightconnection.

Single ply membranes over insulation boardsThemembranemustbeprotectedagainsttheriskoftheinsulationandmembranefastenerpuncturingthemembraneasaresultoffoottrafficcausinglocalcompressionoftheinsulationboard.TelescopesystemssuchastheSFSintecIsotakrangeareautomatically“treadfast”asthefastenerheadissetdowntowardsthebottomofthetelescope.Whereoldstylemetalplateandscrewsystemsareused,thescrewshouldhaveanenlargedthreadundertheheadtoengagewiththeplatewashersoastoresistfoottrafficloads.

Pullovertesting

SheetsupportandthreadfreesectiononSFSinsulatedpanelfasteners

“Treadfast”telescopeIsotak

Technical performance


29

6.4 Dynamic bend resistanceWhereinsulatedpanelsarethrough-fixed,thefastenersarealsosubjecttorepetitivebendingforces.Theseforcesaretypicallygeneratedbypaneldeflectionsfrom(wind)loadingsandthermalmovement.Thisbendingtendstobegreaterinhot-rolledsteelpurlinswhichtendtobelessflexiblethanthinnercold-rolledpurlins.

TheEuropeanConventionforConstructionalSteelwork(ECCS)Document66,PreliminaryRecommendationsforSandwichPanelsdefinesatestmethodtowhichfastenermanufacturershavetobeabletodemonstratecomplianceandadvisethemaximumallowabledeflectionrelativetosteelsupportandpanelthickness.

By2013,manyfastenersforroofingandcladdingwillfeatureCEmarkinginaccordancewiththeEuropeanConstructionProductsDirective.AssessmentforCEmarkingwillincludeaseriesoftestswhichwillincludeabendtestsimilartotheECCStestoutlinedabove.ItisexpectedthattheCEtestprogramwillreplacetheECCSmethodinduecourse.

6.5 UnwindingPitched roofing systemsHistorically,thisphenomenonhasnotbeenwidespreadwithinpitchedroofingsystems.However,whereconditionsofpotentiallyhighdifferentialmovementbetweenthesheetand“lightweight”framingpresentthemselves,cautionintheselectionofthemostappropriatefastenertypeshouldbeexercised,andSFSintecwouldwelcomebeingconsulted.

Flexible membrane systems to “thin” metal decksAsthewindpassesovertheflexiblemembraneaneccentricforcepassesthroughthefastener.TheSFSISOTAKsystemisabletoaccommodatethesedynamicwindloadsbynatureofits“reduced”diameterdrillpoint,thetaperedlead-inthreadsectionanditsshallowthreadpitchangle.Thesefeaturescombinetogivetotalthreadengagementwithinthedeckandtoalsoprovidetheoptimumpulloutfrom“thin”,0.63mmminimum,steeldecks.

6.6 Clamping of membraneForin-seamfasteningofsingleplymembranes,telescopicfastenersaredesignedtoresistanysidewardsmovementofthemembranewhichcouldultimatelyleadtotearing,slippageandfailureofthemembrane.SFSinteccanofferavarietyoffastenerandtubedesignswhich,duetotheirhighclampingqualitiesmayallowa25%increaseinthefastenersafeworkingload.

Unlessthemembranesuppliertakesfullresponsibilityforthefastenerfrequencycalculations,confirmationshouldbesoughtfromtheparticularmembranesupplierthattheproposedfasteningsystemanditspermissibleloadingsareappropriatetotheirmembrane.

6.7 Thermal/cold bridgingApprovedDocumentAD-L2requiresthedesignertocalculatethermalbridgesandconsidertheireffectonbothcondensationandalsoheatlossthroughthebuildingenvelope.

Incertaintypesofroofingandcladdingsystems,fastenersmayaddtoheatlossdependingontheirspecification.

Thethermalconductivityofcarbonsteelasafastenermaterialis60W/mKwhereasausteniticstainlessisonly17W/mK.ThereforespecifyingausteniticmayallowthinnerinsulationtobeusedandstillachievecompliancewiththeBuildingRegulations.

Asanexample,inatypicalflatroofapplicationwith4fastenerspersqm,theadditionalheatlossthrough100mminsulationwithcarbonfastenersexceeds1.5%comparedtoonly0.25%withausteniticstainlessfasteners.Wherecoatedcarbonsteelofferssufficientdurability,thenusingathermallybrokentelescopicsystem(seesection4.2)wouldalsoallowthinnerinsulationtobeused.

highperformancedrilltip

Coldbridgingviaall-carbonsteelfasteners

laboratorytesting



6.8 Overdriving resistanceOverdrivingoffastenersmayleadtothreadstrippingwithinthesupportingstructure,particularlyin“thin”coldrolledsections.“Traditional”designsofselfdrillingthreadedfastenersrelyupontheinstallertotakethenecessarycarenottooverdrive,eitherbyuseofdepthlocatorsonscrewgunsorexperience.Fortwoparticularapplicationswherethefastenerperformanceiscriticialfortheintegrityofthesystem,SFSintechasdevelopedinnovativesolutionswhich,bydesign,cannotbeoverdriven.

SDK fasteners for standing seam 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.SFSintec’sstitchingandclampingfastenersarepurpose-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.

SFSintecclampingfastener



31

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 WindloadingsThenewBSEN1991methodusesanationalannexetoprovidewindvaluesfortheUnitedKingdomandthishascomeintoforcefromJanuary2011,replacingBS6399(andinIrelandCP3).However,EN1991producesdifferentvaluesforagivenlocationwhencomparedwiththeearlierBS6399methodandsosomeworkhasbeencarriedoutusingahybrid,takingvaluesfromboththeBSandENdataandthisseemstobethewayforward(atspring2011).

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 ToolingSections6.1to6.14showthewiderangeofperformancecriteriafastenershavetobecapableofwithstanding.Thesecriteriatendtobespecifictotheparticulartypeofroofingandcladdingsystemandthereforefastenersaredesignedsuchastogiveoptimumperformancecompatiblewiththerequirementsoftheparticularsystem.Whilstsomefastenershavebeendesignedsuchthattheycannotbemis-installed(referto6.8&6.9),toolingsystemsforotherfastenertypesareavailablewhichassisttheContractorintermsofbothspeedandconsistency,aswellasprovidingsecuritytotheClient.

Windcreates+veand-ve(suction)loadsonroofingandcladding



Section 7 Specification design support

7.1 Fastener and sealant specifications for roofing and cladding

Specification advisory service for architects, designers and consultantsAttheearlydetaildesignstageofaproject,complexandsometimesconflictingrequirementscanplacediversedemandsonthefastenerandsealants.Consultationwithanexperiencedtechnicalteamfromthefastenersuppliercanhelpyoutoresolvefastenerandsealingissuesduringtheplanningstages,workingsidebysidewitharchitectsanddesignerstoensurethatperformancerequirementsofthebuildingenvelopearemet,andthecontractspecificationproceedswithoutahitch.

7.1aDilapidation and remedial worksConsultantsthatspecialiseinsurveyingpropertiesthatarechanginghandsoraresubjecttowarrantydisputeswillfindtheSFSintectechnicalservicetobeaninvaluablesourceofadvice,builtonyearsofexperience.

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.

Specification design support


33

Sectio

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pecifi

cation

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’smajorsystemssupplierssuchasTataSteelPanelsandProfilesandtheirPlatinumWarrantySystem–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.

TataSteelandProfilesPlatinumWarranty



35

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,ourexpertiseisonlyaphonecallaway.

Mobile training unitFeatures:• Allweathercapability-comfortableheatedoutdooraccommodationfor upto9people;upto30peopleindoorsatyourpremises• Handondemonstrationsandvideos• Onboardpowersupply• FullrangeofSFStoolingsystemsandproducts• Programmesincludepitchroofing,flatroofing,cladding,rainscreenand facades,logisticsande-business• CPDCertificatesforattendees

Brings SFS intec to your doorstep...



Section 8 Case studies

8.1 First Direct Arena, Leeds

Specialist contractor; Lakesmere

Designer; Populous Project requirements; Durability Section 2.5b Aesthetics Section 5 Weather&airsealing Section 3 & 4 Technicalperformance Section 6

SFS intec products; Austeniticstainlesssteel Section 2.7 irius®colourheads Section 5.2b Clampingfasteners Section 3.3, 4.3, 6.9 Weather&airsealantsTypeA+ Section 3.4 & 4.3

Case studies


37

Sectio

n 8C

ase studies


8.2 WJEC Building, Cardiff

Specialist contractor; SevernInsulation

Designer; CapitaArchitecture 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


8.1 First Direct Arena, Leeds

Specialist contractor; Lakesmere

Designer; Populous Project requirements; Durability Section 2.5b Aesthetics Section 5 Weather&airsealing Section 3 & 4 Technicalperformance Section 6


Case studies



8.3 Cairngorm Funicular Railway

Specialist contractor; AbbeyRoofingSpecialists 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

Case studies


39


8.4 ExCel London Phase 2

Specialist contractor; HathawayRoofing Project requirements; Durability Section 2.5b & c Componentsupplierwarranty Section 2.5e Aesthetics Section 5 Technicalperformance Section 6 Designsupport Section 7



8.3 Cairngorm Funicular Railway

Specialist contractor; AbbeyRoofingSpecialists Project requirements; Durability Section 2.5b & d Componentsupplierwarranty Section 2.5e Aesthetics Section 5 Technicalperformance Section 6 Designsupport Section 7


Case studies


Case studies


8.5 Matalan, Kirkby

Specialist contractor; Longworth

Designer; Fletcher-Rae Project requirements; Durability Section 2.5b Systemsupplierswarranty Section 2.5e Aesthetics Section 5 Weather&airsealing Section 3 & 4 Technicalperformance Section 6



41


8.5 Matalan, Kirkby

Specialist contractor; Longworth

Designer; Fletcher-Rae Project requirements; Durability Section 2.5b Systemsupplierswarranty Section 2.5e Aesthetics Section 5 Weather&airsealing Section 3 & 4 Technicalperformance Section 6


SFS intec Ltd.Fastening Systems153 Kirkstall RoadLeeds LS4 2AT

Tel: 0113 2085 500Email: [email protected]: www.sfsintec.biz/uk

For further information please contact:

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CPD seminars SFSintecofferstheirRIBA-accreditedCPDtechnicalseminarwhich,inconjunctionwiththisguide,helpsyoutobecomefamiliarwithissuesconcerningfastenersandsealants,aswellasenablingyoutoacquireyourRIBACPDpoints!Contactusonthedetailsbelow.