Eurocode 5 Span Tables 4th edition Preview by BM TRADA, Element and Warringtonfire

forsolidtimbermembersinfloors, ceilingsandroofsfordwellings

Eurocode5 spantables

Eurocode5spantables

forsolidtimbermembers

infloors,ceilingsandroofsfordwellings

4thedition

BMTRADA'sSpantablesislongrecognisedasakeyresourceintimberspecificationandbuilding.Itis anessentialtoolforcalculatingthesizeofsolid,softwood,timbermembersnecessarytogiveadequate supporttofloors,ceilingsandroofsindwellings.

SpantableswereoriginallyincludedintheEnglandandWalesBuildingRegulations,Approved DocumentA:Structure.Thetablesarestillreferencedasguidancebutthelatereditionsofthesetables havebeenproducedandupdatedseparatelybyBMTRADA.

Tablesareincludedfordomesticfloorjoists,ceilingjoistsandbinders,rafters,andpurlinssupporting raftersfortraditionalpitchedroofs.Calculationsarealsogivenforpurlinssupportingroofsheetingor cladding,andforflatroofjoists,buttrussedrafterroofsareexcluded.

ThetablescoversoftwoodspeciesandgradecombinationswhichsatisfystrengthclassesC16andC24. This4theditionincludesrevisionsfor:

•enhancedshearstrength:Thosespanswhereshearisthegoverningcriterionhavebeenimproved

•enhancedbearingstrength:Thebearinglengthsrequiredhavereducedwhichinturnincreased theclearspansinsomeinstances

•trimmertables:Spantablesfordoubled-uptrimmerandtrimmingjoistsareincludedandare consistentwiththepermanentloadingsituationsofthefloorjoiststables.Reactionsandfastener tablesareincluded

•changestosomesectionsizes:Anindustrysurveyhaspromptedchangestotherangeofmember sizesofferedinthetables.

Frequentlyaskedquestionsareaddressedinthenotesalongsidethetables.

Contents Preface8 1Introduction10 1.1Howtousethespantables 13 2Timberspecifications14 2.1Timberavailability 15 3Designconsiderations16 3.1Loading 16 3.2Constructionandbasicworkmanshiprecommendations 16 3.3Eurocode5considerations 17 4Tablesofsizesoftimberfloormembers19 4.1Floorjoists 19 4.2Trimmersandtrimmingjoists 23 5Tablesofsizesofceilingmembers55 5.1Ceilingjoistsandbinderssupportingceilingjoists 55 6Tablesofsizesofpitchedroofmembers60 6.1Raftersandpurlinssupportingrafters 60 6.2Purlinssupportingroofsheetingordecking 74 7Tablesofsizesofflatroofjoists79 8References86

Listoftables

Table4.13Permissibleclearspansofdoublemembertrimmingjoistswhichsupportatrimmerandnon-loadbearing lightweightpartitionsnotexceeding1.0kN/mDeadload0.25kN/m²C16timber37

Table4.14Permissibleclearspansofdoublemembertrimmingjoistswhichsupportatrimmerandnon-loadbearing lightweightpartitionsnotexceeding1.0kN/mDeadload0.25kN/m²C24timber38

Table4.15Permissibleclearspansofdoublemembertrimmingjoistswhichsupportatrimmerandnon-loadbearing lightweightpartitionsnotexceeding1.0kN/mDeadload0.50kN/m²C16timber39

Table4.16Permissibleclearspansofdoublemembertrimmingjoistswhichsupportatrimmerandnon-loadbearing lightweightpartitionsnotexceeding1.0kN/mDeadload0.50kN/m²C24timber40

Table4.17Permissibleclearspansofdoublemembertrimmingjoistswhichsupportatrimmerandnon-loadbearing lightweightpartitionsnotexceeding1.0kN/mDeadload1.25kN/m²C16timber41

Table4.18Permissibleclearspansofdoublemembertrimmingjoistswhichsupportatrimmerandnon-loadbearing lightweightpartitionsnotexceeding1.0kN/mDeadload1.25kN/m²C24timber42

Table5.4Ceilingbinders

Table6.1CommonorjackraftersRoofslope15–22.5°Imposedload0.60kN/m²C16timber62

Table6.2CommonorjackraftersRoofslope15–22.5°Imposedload0.60kN/m²C24timber62

Table6.3PurlinssupportingraftersRoofslope15–22.5°Imposedload0.60kN/m²C16timber63

Table6.4PurlinssupportingraftersRoofslope15–22.5°Imposedload0.60kN/m²C24timber63

Table6.5CommonorjackraftersRoofslope15–22.5°Imposedload1.02kN/m²C16timber64

Table6.6CommonorjackraftersRoofslope15–22.5°Imposedload1.02kN/m²C24timber64

Table6.7PurlinssupportingraftersRoofslope15–22.5°Imposedload1.02kN/m²C16timber65

Table6.8PurlinssupportingraftersRoofslope15–22.5°Imposedload1.02kN/m²C24timber65

Table6.9CommonorjackraftersRoofslope22.5–30°Imposedload0.60kN/m²C16timber66

Table6.10CommonorjackraftersRoofslope22.5–30°Imposedload0.60kN/m²C24timber66

Table6.11PurlinssupportingraftersRoofslope22.5–30°Imposedload0.60kN/m²C16timber67

Table6.12PurlinssupportingraftersRoofslope22.5–30°Imposedload0.60kN/m²C24timber67

Table6.13CommonorjackraftersRoofslope22.5–30°Imposedload1.02kN/m²C16timber68

Table6.14CommonorjackraftersRoofslope22.5–30°Imposedload1.02kN/m²C24timber68

Table6.15PurlinssupportingraftersRoofslope22.5–30°Imposedload1.02kN/m²C16timber69

Table6.16PurlinssupportingraftersRoofslope22.5–30°Imposedload1.02kN/m²C24timber69

Eurocode5spantablesforsolidtimbermembers 6

Table1.1Imposedloadsforfloors,ceilingsandroofs 10 Table1.2Summaryoftables 11 Table2.1Commonspecies/gradecombinationswhichsatisfystrengthclassesC16andC24 14 Table3.1SnowroofloadsforthezonesdefinedinFigure3.1 16 Table3.2Struttingorblockingofjoists 17 Table4.1Domesticfloorjoists C16timber21 Table4.2Domesticfloorjoists C24timber22 Table4.3Permissibleclearspansofdoublemembertrimmerswhichsupporttrimmeddomesticfloorjoistsand non-loadbearinglightweightpartitionsnotexceeding1.0kN/m C16timber26 Table4.4Permissibleclearspansofdoublemembertrimmerswhichsupporttrimmeddomesticfloorjoistsand non-loadbearinglightweightpartitionsnotexceeding1.0kN/m C24timber27 Table4.5NailcentresfordoublemembertrimmersinTable4.3 28 Table4.6NailcentresfordoublemembertrimmersinTable4.4 29 Table4.7BoltcentresfordoublemembertrimmersinTable4.3 30 Table4.8BoltcentresfordoublemembertrimmersinTable4.4 31 Table4.9Factored(design)reactionsinkNateachendofdoublemembertrimmerinTable4.3withan incomingpartition 32 Table4.10Factored(design)reactionsinkNateachendofdoublemembertrimmerinTable4.4withan incomingpartition 33 Table4.11Factored(design)reactionsinkNateachendofdoublemembertrimmerinTable4.3withoutan incomingpartition 34 Table4.12Factored(design)reactionsinkNateachendofdoublemembertrimmerinTable4.4withoutan incomingpartition 35

Table4.19NailcentresfordoublemembertrimmingjoistsinTable4.13 43 Table4.20NailcentresfordoublemembertrimmingjoistsinTable4.14 44 Table4.21NailcentresfordoublemembertrimmingjoistsinTable4.15 45 Table4.22NailcentresfordoublemembertrimmingjoistsinTable4.16 46 Table4.23NailcentresfordoublemembertrimmingjoistsinTable4.17 47 Table4.24NailcentresfordoublemembertrimmingjoistsinTable4.18 48 Table4.25BoltcentresfordoublemembertrimmingjoistsinTable4.13 49 Table4.26BoltcentresfordoublemembertrimmingjoistsinTable4.14 50 Table4.27BoltcentresfordoublemembertrimmingjoistsinTable4.15 51 Table4.28BoltcentresfordoublemembertrimmingjoistsinTable4.16 52 Table4.29BoltcentresfordoublemembertrimmingjoistsinTable4.17 53 Table4.30BoltcentresfordoublemembertrimmingjoistsinTable4.18 54 Table5.1Ceilingjoists C16timber57 Table5.2Ceilingjoists C24timber58

C16timber59

Table5.3Ceilingbinders

C24timber59

Table6.17CommonorjackraftersRoofslope30–45°Imposedload0.60kN/m²C16timber70

Table6.18CommonorjackraftersRoofslope30–45°Imposedload0.60kN/m²C24timber70

Table6.19PurlinssupportingraftersRoofslope30–45°Imposedload0.60kN/m²C16timber71

Table6.20PurlinssupportingraftersRoofslope30–45°Imposedload0.60kN/m²C24timber71

Table6.21CommonorjackraftersRoofslope30–45°Imposedload1.02kN/m²C16timber72

Table6.22CommonorjackraftersRoofslope30–45°Imposedload1.02kN/m²C24timber72

Table6.23PurlinssupportingraftersRoofslope30–45°Imposedload1.02kN/m²C16timber73

Table6.24PurlinssupportingraftersRoofslope30–45°Imposedload1.02kN/m²C24timber73

Table6.25PurlinssupportingsheetingordeckingRoofslope10–30°Imposedload0.60kN/m²C16timber75

Table6.26PurlinssupportingsheetingordeckingRoofslope10–30°Imposedload0.60kN/m²C24timber76

Table6.27PurlinssupportingsheetingordeckingRoofslope10–30°Imposedload1.02kN/m²C16timber77

Table6.28PurlinssupportingsheetingordeckingRoofslope10–30°Imposedload1.02kN/m²C24timber78

Table7.1Flatroofs–accessformaintenanceandrepaironlyImposedload0.60kN/m²C16timber80

Table7.2Flatroofs–accessformaintenanceandrepaironlyImposedload0.60kN/m²C24timber81

Table7.3Flatroofs–accessformaintenanceandrepaironlyImposedload1.02kN/m²C16timber82

Table7.4Flatroofs–accessformaintenanceandrepaironlyImposedload1.02kN/m²C24timber83

Table7.5Flatroofs–unlimitedaccess Imposedload1.50kN/m²C16timber84

Listoffigures

Table7.6Flatroofs–unlimitedaccess Imposedload1.50kN/m²C24timber85

Figure1.1Keytomembersincludedinthespantables 10 Figure3.1Snowroofloadingzones–derivedfromEC1 16 Figure4.1Floorjoistsarrangement 19 Figure4.2Fixings–spacing,edgeandenddistances 24 Figure4.3Planondoublemembertrimmersupportingtrimmedjoists 25 Figure4.4Planondoublemembertrimmingjoistsupportingdoublemembertrimmer 36 Figure5.1Ceilingjoistsandbinderarrangement 56 Figure6.1Typicalraftersandpurlinarrangement 60 Figure6.2Purlinssupportingroofsheetingordecking 74 Figure7.1Typicalflatroofjoistsarrangement 79

Preface

TheadoptionofEurocodesisamilestoneinharmonisingtheapproachtothedesignofstructures acrossEurope.Thispan-Europeanapproacheliminatesanobstacletotrade.Italsodrawsonthe expertiseofengineersacrossallmembersofTheEuropeanCommitteeforStandardization(CEN) insteadofindividualmemberstates.

However,thereisanotherbigadvantagefordesignersusingtheEurocodes.Steelandconcrete designershaveusedthelimitstatemethodforsometimewhiletimberdesignershaveretainedthe permissiblestressmethod.TheevolutionoftheEurocodes’unifiedapproachtodesign,regardlessof thematerialsused,meansthatdesignerswhoarealreadywellversedinthedesignofconcreteand steelstructuresnowhavelittledifficultyworkingwithtimber.

Thesespantablesforsolidtimbermembersinfloors,ceilingsandroofs(excludingtrussedrafters)have beenproducedbyBMTRADAtosupplementtheApprovedDocumentA:Structure(ADA)forusein England.FromOctober2013,theApprovedDocumentAreferstoEurocode5(EC5),theUKNational AnnextoEC5(UKNAtoEC5)andPublishedDocument6693(PD6693)forthedesignoftimber buildings.PD6693supplementsEC5andtheUKNAtoEC5bypresentingsomeoftheinformation thatwaslostwhenmigratingtoEC5fromBS5268.ThetablescoverstrengthclassesC16andC24as listedinBSEN338StrengthClasses

TimberspantableswereincludedinearliereditionsofADA.WhentheyweretakenoutoftheADA, TRADAassumedresponsibilityformaintainingandpublishingthem.The2ndeditionofTRADA’s spantableswasbasedonBS5268andthethirdeditionwascompletelyrevisedtocomplywith Eurocode5.

Thespansinthis4theditionarecalculatedinaccordancewiththeEurocodes,inparticular:

BSEN1995-1-1Eurocode5Designoftimberstructures.Commonrulesandrulesforbuilding, NAtoBSEN1995-1-1UKNationalAnnextoEurocode5Designoftimberstructures.General. Commonrulesandrulesforbuildings,and

PD6693-1RecommendationsforthedesignoftimberstructurestoEurocode5:Designoftimber structures.General.Commonrulesandrulesforbuildings

DuringthetransitionfromBritishStandardstoEurocodes,designersmustensuretheyuseaconsistent setofstandardsanditisnotadvisabletomixandmatchBritishStandardsandEurocodes.

Thispublicationdealssolelywiththeloadbearingcapacityofthesolidtimbermembers.Therearemany otheraspectsthatmustbeconsideredindesigningafloor,ceilingorroof,whicharenotincludedhere. Inpreparingthispublication,BMTRADAhasassumedthatthecompletedesignwillbeundertakenby acompetentperson.TheappropriatesectionsoftheRegulations,ApprovedDocumentsandrelevant Standardsshouldbeconsultedforguidance.

Thesespantablescannotbeadaptedforhardwoodsorengineeredtimberproducts.Designersshould specifyengineeredtimberproductsthatareindependentlycertifiedforwhichmanufacturersshould supplyspantablescalculatedinaccordancewithEC5.

Changesinthis4thedition

Enhancedshearstrength:ChangestoBSEN338in2009includedimprovementsfortheshear strengthofbothC16andC24strengthclasses.Forthemajorityofinstancesinthelistedspansthishad noeffectasthefailurewasmostlygovernedbydeflection.However,ahandfulofspanswhereshear wasthegoverningcriterionbeforehavebeenimprovedasaresult.

Enhancedbearingstrength:UKCodeCommitteefortheStructuralUseofTimberhasclarifiedin PD6693theuseofcompressionperpendicularfactorkc,90 inrelationtosimplysupportedbeams.Prior tothisclarification,itwasnotpossibletoincludethehighervaluesforkc,90 asthesespansareproduced forageneralsituationandnotforanyspecificbearingcondition.Thiseditionnowusesakc,90 factor of1.5throughout.Asaresult,thenominalbearinglengthsrequiredhavebeenreducedwhichinturn increasedtheclearspansforcertaininstances.Toobtainmeaningfullengthsofbearingachievedin construction,additionalbearinglengthsof30mmallowedeithersideofasupport(seeEC5Clause 6.1.5(1))havenotbeenusedexceptfortrimmersandtrimmingjoists.

Trimmertables:Spantablesfordoubled-uptrimmerandtrimmingjoistshavebeenre-introduced inthisedition.Trimmerandtrimmingjoisttableswereoriginallypublishedinthe2ndeditionbutonly coveredalimitednumberofpermanent(dead)loadingoptions.Thetablespresentedinthiseditionare nowconsistentwiththepermanentloadingsituationsofthefloorjoiststables.Reactionsandfastener tablesfortrimmersandtrimmingjoistshavealsobeenexpandedtobeinlinewiththetrimmerand trimmingjoisttablesthemselves.

Changestosectionsizes:Anindustrysurveyhaspromptedafewchangestotherangeofmember sizesofferedinthetables.

Preface 9

1.1Howtousethespantables

Theobjectiveofthespantablesistoindicatethemaximumspanofasoftwoodmembersubjectto:

•itsapplication

•itsspacing

•thedeadandimposedloadsitmustsupport

•themoistureenvironment

•thestrengthgradeofthetimber.

Theapplicationisdefinedinthetablecaption.

Thedeadloadisusuallyavariablewithineachtable.Thefiguresgivenfortheuniformlydistributed deadloadareforceswhichcorrespondtothefollowingapproximateweightsofthebuildingelement beingsupported:

•0.25kN/m2 isapproximately25kg/m2

•0.50kN/m2 isapproximately50kg/m2

•0.75kN/m2 isapproximately75kg/m2

•1.0kN/m2 isapproximately100kg/m2

Theimposedloadisthatforadwellingandissetforthewholetable.

Themoistureenvironmentisdefinedastheserviceclass.Throughoutthesetables,thespansaresuitable forserviceclasses1and2.Serviceclass2isthemoresevereandcorrespondsto‘externaluseswhere memberisprotectedfromdirectwetting’.EC5givesthesameresultsforserviceclasses1and2.

ThetablesareofferedforstrengthgradeC16softwoods(acommongradeforsoftwoodsgrownin Britain)andC24softwoods(whicharemoreexpensiveandareusuallyimportedfromnorthernEurope). Ifthespanfigureisshaded,itmeansthatadditionalbearinglengthisneededatthesupports. Anasteriskmeansspecialcircumstancesmayapply,suchasadditionaljoiststosupportpartitions.

Inthefollowingexample,basedonFigure4.1,38x145mmjoistsspacedat600mmcentreswillspan upto2.49mwhensupportingafloorweightupto25kg/m2

1Introduction 13

4.0Tablesofsizesoftimberfloormembers

4.1Floorjoists

4.1.1 Tables4.1and4.2givepermissibleclearspansofsimplysupporteddomesticfloorjoistsofsolidtimber forspecifiedloadings,sizesandspacingscalculatedinaccordancewithEC5

4.1.2Themethodofcalculationmakesnoallowanceforanycontributionoftheflooringtotheloadresistance ofthejoists.

4.1.3Shorterspansaremoresusceptibletotheeffectofconcentratedloads.Inthesespantables,wehave assumeda‘slabloading’effectdescribedinthenotebelowtodissipateconcentratedloadstoadjacent parallelelements(followingthepracticeinBS5268-7.1).Ifthiswerenotdone,theresultingsections wouldbesignificantlydifferentthaninthe2ndedition.

Thesizes,spacingandspansgiveninTables4.1and4.2willsupportthedeadloadsstatedinthe tablestogetherwithanimposedloadnotexceeding1.5kN/m2

Note:PreviouseditionsofthesespantablesfollowedexactlytheproceduresetoutinBS5268-7.1 WhenBS5268-7.1waspublished,theloadingcodeBS6399-1saidthatfordomesticfloorsthepoint loadof1.4kNcouldbeignored,soBS5268-7.1didnotapplythis.Theexemptionwasprobablybecause, forspansover2.4m,the1.4kNpointloadnevergovernedthespanwithdomesticfloorloading.For spanslessthan2.4mBS5268-7.1usedamoreonerousdistributedloadcalleda'slabload'. Thisfourtheditionfollowsthesameprincipleandusesasuitablydefined'slabload'.

4.1.4Fordeadloadsthetraditionalassumptionwasthat:

0.25kN/m²wasforsuspendedgroundfloorswithnoplasterboardorpartitionallowance;

0.5kN/m²wasforintermediatefloorswithnopartitionallowance;

1.25kN/m²wasforpartyorcompartmentfloorswithnopartitionallowance.

However,withmodernmaterialsandinsulationrequirements,itislikelythattoday’sfloorsweighmore thantheabove,eg0.6kN/m2 foranintermediatefloor.TrimmerandTrimmingJoisttablesaretherefore nowextendedtocoverallthreeloadsituationsabove.Calculatetheactualweightoftheflooranduse theappropriatecolumninTable4.1or4.2

Note:TRADA’sonlineTimbersizersoftwareallowstheexactloadsbeenteredtoproducethemost economicalsolution.Formoreinformationvisitwww.trada.co.uk.

4.1.5

Tables4.1and4.2makenoallowanceforconcentratedorlineloadsappliedbypartitions,trimmersor othersimilarcauses.Lightweight,non-loadbearingpartitionswhichweighnomorethan1.0kNpermetre runandareparalleltothejoistsmaybesupportedbyoneortwoadditionaljoistsplacedimmediately

4Floormembers 19

Figure4.1Floorjoistsarrangement

6.0Tablesofsizesofpitchedroofmembers

6.1Raftersandpurlinssupportingrafters

6.1.1

Tables6.1to6.24givepermissibleclearspansofsimplysupportedraftersandpurlinsofsolidtimber usedintraditionalpitchedroofconstructionswithaslopefrom15°to45°underspecifiedloading,sizing andspacingconditions.

6.1.2Thesespantablesdonotapplytotrussedrafterroofs.

6.1.3PermissibleclearspanshavebeencalculatedinaccordancewithEC5.RefertoSection3.3.1for additionalinformationonthemethodused.Itisassumedthattheraftersarenon-continuousoverthe purlins,buttheymaybecontinuous.Itisassumedthatthepurlinsaresinglespanmembersbutthey maybecontinuousoverasupport.

6.1.4Whenthespansoftheraftersorpurlinsareunequal,thesectionsizesshouldbedeterminedbythe longestspan.Forapurlinspanningbetweentwosupportingwalls,thelongestspanisthecleardistance betweenthetwowalls.Forapurlinwithanintermediatepost,thelongestspanisthelargeroftheclear distancebetweenonewallandthepostandthecleardistancebetweenthepostandtheotherwall.

6.1.5ForTables6.1to6.24thevalueshavebeencalculatedaccordingtoEC5withanupperlimitontheroof slopeof60°fortheimposedsnowload.

6.1.6Themethodofcalculationmakesnoallowanceforanycontributionofotherpartsoftheroofstructure orcoveringtotheloadcarryingcapacityoftheraftersalthoughitisassumedthatthetilingbattensare capableofprovidinglateralloaddistributionandlateralsupport.

6.1.7Thesespantablescover'canted'purlinsinstalledperpendiculartotheslopeoftheroof.Horizontal thrusttransmittedbytheraftersisassumedtoberestrainedbytheceilingjoistsorothersuitablemeans.

6.1.8Thesizes,spacingandspansgiveninTables6.1to6.24willsupportthedeadloadsstatedinthetables togetherwitheitheranimposedloadof0.60kN/m2 or1.02kN/m2 oraconcentratedloadof0.9kN.The deadloadismeasuredonslopeandthesnowloadismeasuredonplan.

SeeFigure3.1andTable3.1forguidanceonthesnowloadrelevantforaparticularsite.

Forpurlins,theself-weightofrafterswastakenforsystemof50mmx150mmraftersat450mmcentres.

Eurocode5spantablesforsolidtimbermembers 60

Figure6.1Typicalraftersandpurlinarrangement

Eurocode5spantables