02
Timber-framed Construction
for Multi-residential Buildings
Class 2, 3 & 9c
Design and construction guide for BCA compliant
sound and fire-rated construction
Technical Design Guide issued by Forest and Wood Products Australia


01

04

09

Building with Timber
in Bushfire-prone Areas
BCA Compliant Design and Construction Guide
Technical Design Guide issued by Forest and Wood Products Australia

Timber-framed Construction
for Townhouse Buildings
Class 1a
Design and construction guide for BCA compliant
sound and fire-rated construction

Timbe
r Floo
ring
for inst

Desig
n guide

Technica

l Desi

Technical Design Guide issued by Forest and Wood Products Australia

gn Guid

e issu

ed by

Forest

allatio
n

and Woo

d Prod

ucts

Australia

TechnicalDesignGuides
A growing suite of information, technical and

training resources created to support the use of
wood in the design and construction of buildings.

WoodSolutionsisanindustryinitiativedesignedtoprovide
independent,non-proprietaryinformationabouttimberand
woodproductstoprofessionalsandcompaniesinvolvedin
buildingdesignandconstruction.
WoodSolutionsisresourcedbyForestandWoodProducts
Australia(FWPA).ItisacollaborativeeffortbetweenFWPA
membersandlevypayers,supportedbyindustrypeak
bodiesandtechnicalassociations.

Topics include:

ThisworkissupportedbyfundingprovidedtoFWPA
bytheCommonwealthGovernment.

#01 Timber-framed Construction for
Townhouse Buildings Class 1a

ISBN978-1-920883-79-9

#02 Timber-framed Construction for
Multi-residential Buildings Class 2, 3 & 9c
#03 Timber-framed Construction for
Commercial Buildings Class 5, 6, 9a & 9b
#04 Building with Timber in Bushfire-prone Areas
#05 Timber service life design Design Guide for Durability
#06 Timber-framed Construction Sacrificial Timber Construction Joint
#07 Plywood Box Beam Construction

for Detached Housing
#08 Stairs, Balustrades and Handrails
Class 1 Buildings - Construction
#09 Timber Flooring - Design Guide for Installation
#10 Timber Windows and Doors
#11 Timber-framed Systems for External Noise
#12 Impact and Assessment of
Moisture-affected, Timber-framed Construction
#13 Finishing Timber Externally
#14 Timber in Internal Design
#15 Building with Timber for Thermal Performance
#16 Massive Timber Construction Systems
Cross-laminated Timber (CLT)
OtherWoodSolutionsPublications
R-Values for Timber-framed Building Elements
To view all current titles or for more information
visit woodsolutions.com.au

Researcher:
TimberDevelopmentAssociation(NSW)
Suite604-486PacificHighway
StLeonardsNSW2065
Produced:May2010
Revised:August2012
© 2012 Forest and Wood Products Australia Limited.
All rights reserved.
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Table of Contents


Introduction

4

Step1–High-LevelBCADesignIssues

6

1.1 DeterminetheClassofBuilding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 BCACompliance–DeemedtoSatisfyorAlternativeSolution. . . . . . . . . . . . . . . . . . . 6
1.3 DeterminetheSetoutofSoleOccupancyUnits(SOU)intheBuilding . . . . . . . . . . . . . . 7
Step2–DefineBCASound-DesignRequirements

8

2.1 UtilisingtheDeemedtoSatisfyProvisionsforSoundDesign . . . . . . . . . . . . . . . . . . . 8
2.2 DeterminingSoundInsulationRequirementsforIndividualBuildingElements . . . . . . . . . .10
2.3 Services. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
2.4 TheNextStep. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Step3–ImproveandUpgradeSoundPerformance

12

3.1 AttentiontoBuildingDesigntoReduceSoundTransmission . . . . . . . . . . . . . . . . . . .12
3.2 AddressingFlankingNoise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
3.3 StrategiesforUpgradingSoundPerformanceinConstruction . . . . . . . . . . . . . . . . . .15
3.4 TheNextStep. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Step4–DefineBCAFire-DesignRequirements


17

4.1 UtilisingtheDeemedtoSatisfyProvisionsforFireDesign. . . . . . . . . . . . . . . . . . . . .17
4.2 DeterminingtheTypeofConstructionRequired . . . . . . . . . . . . . . . . . . . . . . . . . .17
4.3 DeterminingFireResistanceLevelsforBuildingElements . . . . . . . . . . . . . . . . . . . .18
4.4 SpecialFireIssues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
4.5 TheNextStep. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Step5–SelectSound-andFire-RatedTimberConstructionSystems

25

5.1 PrinciplesforAchievingFireResistanceLevelsinTimber-FramedConstruction . . . . . . . . .25
5.2 PrinciplesforAchievingSoundInsulationinTimber-FramedConstruction . . . . . . . . . . . .28
5.3 Sound-andFire-RatedWallConstructionSystems . . . . . . . . . . . . . . . . . . . . . . . .33
5.4 ConstructionJoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
5.5 TreatmentofRoof/CeilingandEavesVoids. . . . . . . . . . . . . . . . . . . . . . . . . . . .48
5.6 ShaftsandServicePenetrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51
5.7 VerticalSeparationinExternalWallstoProtectOpeningsfromFire . . . . . . . . . . . . . . . .55
5.8 Non-Fire-IsolatedStairways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
5.9 Archways,WindowsandDoors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57
5.10Smoke-ProofWalls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58
5.11CavityBarriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
Step6–FurtherDesignAssistance(Appendices)

62

AppendixA–ResolvingStructuralDesignConsiderations. . . . . . . . . . . . . . . . . . . . . . .62
AppendixB–DeemedtoSatisfyFireRequirementsNotCoveredbythisGuide . . . . . . . . . . .63
AppendixC–DesignReferences. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
AppendixD–Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 3


Introduction
This Guide covers
fire and sound.
It also picks up
where the BCA
leaves off – in areas
of increasing interest
to users.

Fireandsoundareimportantissuesinresidentialconstruction.Soundinsulationtendsto
governthechoiceofconstructionsystembecauseofitsdailyimpactonthequalityoflife,
whilefire-resistingconstructionisimportantforprotectingagainstextremeevents.This
Guideaimstoassistinbothareasandisspecificallywrittenforusebydesigners,specifiers,
builders,codeofficialsandcertifyingauthorities.Itisset-outaccordingtoasimplestepby-stepprocessshowninFigure1.Thestepsarethenusedasthebasisforheadings
throughouttherestofthedocument.Detailsonthescopeandotherimportantaspectsofthe
Guidearebelow.
Scope
Fortimber-framedconstruction,thisGuidedemonstratesachievementoftargetedfire-andsoundPerformanceRequirementsintheBuildingCodeofAustralia(BCA)forClass2,3and9cbuildings.In
thiscontext,theGuideprovidescertifiedconstructiondetailsthatutilisetheBuildingCodeofAustralia
DeemedtoSatisfyProvisions.Specificareasofperformanceaddressedinclude:
• soundinsulationofwall,floorandceilingelementsrelevanttoSoleOccupancyUnitsand
surroundingconstruction;and
• fire-resistingconstructionofwall,floorandceilingelementsrelevanttoSoleOccupancyUnitsand
surroundingconstruction.
Inaddition,thisGuideprovidesassistanceforthosewantingtoimproveandupgradesound

performancebeyondminimumBCArequirements,includinglowfrequencyimpactsound,vibrationinducedsoundandflankingnoise.Evidently,theseissuesarebeginningtodominateend-user
requirementsandrequirespecificattention.
ThisGuidedoesnotdealwithallaspectsoffiresafetyandsoundinsulation.Forfurtherdetailsonthis
issuerefertoAppendixB–DeemedtoSatisfyfirerequirementsnotcoveredbythisGuide.
Finally,thisGuidedoesnotprovideadviceonwhichtestedwallandfloorsystemsshouldbeused
astherearemanysuppliersofthesesystems.TheGuideprovidesadviceinmanyinstancesonhow
thesetestedsystemsarejoinedandinteractwhilemaintainingtheobjectivesoftheBCA.
Evidence of Suitability
TheBCArequireseverypartofabuildingtobeconstructedinanappropriatemannertoachieve
therequirementsoftheBCA.ThisGuidehasbeenpreparedfromanumberofsources,themain
beingaguidecalled–Timber-FramedConstructionSacrificialTimberConstructionJoints–Technical
DesignGuideforBCAcompliantfire-ratedconstruction.Thisguidealsodocumentsthefiretestsand
assessmentsusedtosupportthedetailsusedinthismanual.
OtherinformationsourcesthatsupportthisguidearereferencedinAppendixC.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 4


Regulatory Differences Between States of Australia
Although national,
some BCA provisions
differ by state.
It's vital to know
key variations for
your area.

ThispublicationfocusesoncurrentBCArequirements.FromtimetotimeState-basedBCA
amendmentsmayvaryrequirements.TheuserofthisGuideshouldmakethemselvesawareofthese

differencesandshoulddevelopafullunderstandingoftheresultingimplications.ThisGuideshould
beusedonthisbasis.
Design process for sound- and fire-resistant timber-framed construction.
Step1–High-LevelBCADesignIssues
DeterminetheClassofbuilding
DeterminethebasisforcomplyingwithBCAPerformance
Requirements,i.e.DeemedtoSatisfyProvisionstobeused

DeterminethesetoutofSoleOccupancyUnitsinthebuilding
Step2–DefineBCASoundDesignRequirements
UtilisetheDeemedtoSatisfyProvisionsforsounddesign
Determinesound-insulationrequirementsforelements,e.g.walls.floors
Step3–ImprovingSoundPerformance
Attentiontobuildingdesign(spaceandform)
Addressflankingnoise
Strategiesforimprovingsoundperformance
Step4–DefineBCAFireDesignRequirements
UtilisetheDeemedtoSatisfyProvisionsforfiredesign
DeterminetheTypeofConstructionrequiredforfire-resistance
DeterminetheFireResistanceLevelsofelements,e.g.walls,
Addressspecialfireissues,e.g.stairs,shafts
Step5–Selectfire/soundratedtimberconstruction
Principlesinfire/soundratedtimberconstruction
Selectafire/soundratedtimber-framedsystem
Detailtheselectedsystem,e.g.joints,penetrations
Step6–Furtherdesignassistance(Appendices)
Structuralconsiderations,otherBCArequirements,references,glossary

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c


Page 5


1
This Guide covers
BCA Class 2, 3 and
9c buildings.

Step 1 – High-Level
BCA Design Issues
TheBCAistheregulatoryframeworkfordeterminingminimumconstructionrequirements
foralltypesofbuildingsinAustralia.Itcontainsdifferentlevelsofdetailthatsubsequently
causedifferentlevelsofdecisionstobemadeonabuildingproject.Aselectionofhigh-level
designissuesrelatingtofire-resistingandsound-insulatingconstructionareaddressedin
thissectionoftheGuide.
1.1 Determine the Class of Building
TheBuildingCodeofAustralia(BCA)containsmandatoryPerformanceRequirementswhichapplyto
10primaryclassesofbuilding.Theclassesaredeterminedaccordingtothepurposeforwhichthe
buildingwillbeused.TheclassesrelevanttothisGuideare:
• Class2buildings–buildingscontainingtwoormoresole-occupancyunitseachbeingaseparate
dwellinge.g.apartmentbuildings.
• Class3buildings–aresidentialbuildingwhichisacommonplaceoflong-termortransientliving
foranumberofunrelatedpersons,including:
–aboarding-house,guesthouse,hostel,lodging-houseorbackpackersaccommodation;
–aresidentialpartofahotel,motel,school,detentioncentreorhealth-carebuilding(whereaccommodatingmembersofstaff);and
–accommodationfortheaged,childrenorpeoplewithdisabilities.
• Class9cbuildings–abuildingofapublicnatureinvolvingagedcare.
TheseclassesaredealtwithinVolume1oftheBCAandsoallfuturereferencestotheBCAaremade
withrelevancetothisvolume.ItisimportantthatuserschoosewhichClassisrelevanttotheirbuilding
projectbecauseitaffectstheTypeofConstruction,andconsequentlyitsfire-resistance.Thisinturn,

influencesthetimber-framedconstructionsystemthatwillbeneededfortheproject.
1.2 BCA Compliance – Deemed to Satisfy or Alternative Solution
BCAPerformanceRequirementscanbeachievedfortheabovebuildingclassesintwoways:

Refer to:
BCA A0.9 and A2.2.

• DeemedtoSatisfyProvisions–thismeansaspecifictypeofconstructionthatisacknowledgedas
complyingwiththeBCA’sPerformanceRequirements.
• AlternativeSolutions–thismeansasolutionnotdealtwithunderDeemedtoSatisfyProvisions
andmustbeproventosatisfyBCAPerformanceRequirements.Suitableassessmentmethodsare
identifiedintheBCA.
TheconstructionsystemsanddetailsinthisGuidecomplywiththeDeemedtoSatisfyProvisions.For
instance,theseprovisionsdirecttheleveloffireandsoundresistancethatconstructionelementsmust
achieveinordertomeetminimumBCArequirements.ApprovedBCAmethodsofassessmentare
thenusedtoensurethatthetimber-framedconstructionsystemsshowninthisGuidecomplywiththe
levelsrequired.
Intheeventthatasatisfactorytimber-framedsolutioncannotbeobtainedundertheDeemedtoSatisfy
solutionsintheGuide,thenanAlternativeSolutionisrequired.AlternativeSolutionsarenotdealtwith
inthisGuide.
ItisimportanttonotethatamixtureofDeemedtoSatisfyProvisionsandAlternativeSolutionscanbe
usedtodevelopanacceptablesolutionforabuilding.Theuserdoesnotneedtofollowoneorthe
otherpath.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 6


1.3 Determine the Setout of Sole Occupancy Units (SOU) in the Building

TheconceptofaSoleOccupancyUnit(SOU)iscentraltoaddressingmanyissuesconcerningfire
andsoundperformanceinClass2,3and9cbuildings.ASOUhelpsseparateagivenbuildinginto
manageableunitsfordealingwithfireandsoundperformance:
• ASOUisaroomorotherpartofabuildingforoccupationbyanowner,leasee,tenantorother
occupier,totheexclusionofothers.
• SOUsmustbedesignedtorestrictfireandsoundenteringadjoiningSOUsandcertainotherparts
ofthebuilding.
Thewallandfloor/ceilingelementsthatboundanSOU(Figure2)arecentralinachievingBCAsound
andfireperformance,butspecificrequirementsvarydependingonwhethertheSOUsare:
• sidebyside;
• stackedontopofeachother(aswellassidebyside);
• adjoiningroomsofadifferenttypeorspace(suchasapubliccorridor);or
• adjoiningroomsofsimilarusageback-to-back,e.g.back-to-backhabitableareasorback-to-back
serviceroomssuchaslaundriesorkitchens.
Note:ThoughboundingwallandfloorelementsofaSOUidentifythemainsound-andfire-rated
elements,itisalsohighlylikelythatcertaininternalwallsandfloorswillalsoneedtobefire-ratedwhen
theyaresupportingfire-ratedwalls/floorslocatedabove.

Store
Not an
SOU

SOU

SOU

Store
Not an
SOU


SOU

SOU

SOU

SOU

SOU

SOU

SOU

SOU

Elevation view

Store
Not an
SOU

SOU

SOU

SOU

SOU


SOU

Store
Not an
SOU

SOU

Plan view

Figure 2: Examples of Sole Occupancy Units.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 7


2
Refer to:
BCA F5.0 to F5.7.

Step 2 – Define BCA Sound-Design
Requirements
Intoday’sbuildingdesign,soundinsulationtendstogovernthechoiceoftimber-framedconstruction
moresothanfirerequirements.IntermsoftheBCA,designingsoundresistingconstructioninvolves
aprocessofunderstandinghowPerformanceRequirementstranslateintothemoreobjectiveand
measurableDeemedtoSatisfyProvisions,thenselectingtimber-framedconstructionsystemsthatsuit
theserequirements.AswillbediscussedinStep3,thereisaparallelneedtoaddresssoundinduced
bypoorspatialdesignofabuilding,flankingnoiseproblems,andwhereappropriate,upgradedsound
performancerequirementstomeetenduserneeds.

2.1

Utilising the Deemed to Satisfy Provisions for Sound Design

PartF5oftheBuildingCodeofAustralia(BCA)isconcernedwith'safeguardingbuildingoccupants
fromillnessorlossofamenityasaresultofexcessivenoise'.BCAPerformanceRequirementsfocus
onthesoundinsulationofwallandfloorelementsboundingSoleOccupancyUnitswhereseparating:
• adjoiningunits;and
• commonspacesfromadjoiningunits.
Airborne and impact
sound: different
sources need
different handling.

ProvisionsthatmeettheabovePerformanceRequirementsaredetailedintheBCAundersectionF5
whichcoverstheairborneandimpactsound-insulationratingsforwalls,floorsandservices(Note:
theprovisionsalsoincludethesoundisolationofpumpsbutissuespertainingtothisarenotdealt
withinthisGuide).Ininterpretingtheserequirements,itisimportanttohaveanunderstandingofthe
differencebetweenairborneandimpactsound(Figure3).

Airborne sound

Impact sound

Figure 3: Examples of impact and airborne sound.

Itisalsoimportanttounderstandhoweachtypeofsoundismeasuredinordertoselectappropriately
sound-insulatedwall,floorandceilingelements.Tothisend,thenomenclatureusedintheDeemed
toSatisfyProvisionsusingresultsfromlaboratoryrequirements,isexplainedinFigure4andFigure5.
NOTE:Alternativemethodsofsoundmeasurementalsoexist.


#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 8


AirbornesoundistypicallymeasuredintheDeemedtoSatisfy
ProvisionsusingtheWeightedSoundReductionIndexandis
expressedasRw(e.g.Rw50).
•Itistypicallyappliedtobothwallandfloorelements.
•Thehigherthenumberthebettertheperformance.
•Itcanbeusedonitsownormodifiedusingthespectrum
adaptiontermCtrfactor(seebelow).

ACtr.modificationfactorcanbeaddedtotheRwmeasurement
tobiastheoverallmeasurementtotakegreateraccountoflow
frequencynoise(bass,subwoofer).
Ctrisusuallyanegativenumberwithatypicalrangeof-1to-15,
andso,eventhoughitisaddedtotheRwvalue,thenetresultisa
lowernumberthantheRwvalueonitsown.Itisthereforesignificantly
hardertoachieveRw+Ctr50thanRw50onitsown.

ApplyingtheaboveinvolvesfindingouttheminimumstatedRwor
Rw+Ctrforagivenbuildingelement(asdeterminedusingthe
DeemedtoSatisfyProvisions)asdealtwithinSection5.2inthisguide.

Figure 4: Methods of measuring airborne sound.

ImpactsoundistypicallymeasuredintheDeemedtoSatisfy
ProvisionsusingtheWeightedNormalisedImpactSoundPressure

LevelexpressedasLn,w(e.g.Ln,w62).
•Itisusuallyappliedtofloorelements.
•Thelowerthenumberthebettertheperformance.
•Itcanbeusedonitsownormodifiedusingspectrumadaption
termCl(seebelow).

AClmodificationfactorcanbeaddedtotheLn,wfigureto
biastheoverallmeasurementintotakinggreateraccountoflow
frequencyimpactsoundsuchasfootsteps.Itisusuallyapositive
number,andsowhenaddedtotheLn,wmeasurement,thenet
resultisahighernumberthantheLn,wmeasurementonitsown.Itis
thereforesignificantlyhardertoachieveLn,w+Cl62thanLn,w62on
itsown.

ApplyingtheaboveinvolvesfindingoutthemaximumstatedLn,wor
Ln,w+Clforagivenbuildingelement(asdeterminedusingtheDeemed
toSatisfyProvisions)asdealtwithinSection5.2inthisguide.

Figure 5: Measuring impact sound.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 9


2.2

Determining Sound Insulation Requirements for Individual Building Elements

Ofimportancetoconstructionistheminimumairborneandimpactsoundinsulationrequirementsfor

individualbuildingelements,e.g.wallandfloorelements.Table1andTable2provideasimplemeans
forfindingoutsuchinformationandisnecessaryforselectingappropriatetimber-framedconstruction,
system.
Table 1: Deemed to Satisfy Sound Insulation Requirements in Class 2 and 3 Buildings.
Situation

WallRating

Entry
Door
Rating

SOU–generally
SOU–generallyall
Rw+Ctr≥50,&
allspaces
spacesexceptthosenote
exceptthose
Ln,w+CI≤62
below
notedbelow

Rw+Ctr≥50

N/A

SOU–bathroom
sanitary
SOU–habitableroom
(exceptkitchen)

compartment,
laundrykitchen

Rw+Ctr≥50
andof
discontinuous1
construction

N/A

Rw≥50

Rw≥30

N/A

Rw≥50

Rw≥30

Rw+Ctr≥50,&

Rw≥50andof
discontinuous1
construction

Rw≥30

FirstSOU/space


Clear definitions +
accurate
measurements =
optimal results.

AdjoiningSOU/space

Publiccorridor,
areasof
different
classification,
publiclobbyor
thelike

SOU–allspaces

Stairandlift
shaft

SOU–allspaces

Plantroom

SOU–allspaces

FloorRating

Rw+Ctr≥50,&
Ln,w+CI≤62


Rw+Ctr≥50,&
Ln,w+CI≤62

Ln,w+CI≤62

Notes: Discontinuous construction refers to walls having a minimum 20 mm gap between separate leaves and
with no mechanical linkages between wall leaves except at the wall periphery.

Table 2: Deemed to Satisfy Requirements for Sound Insulation of Wall and Floor Elements in
Class 9c Buildings.
Situation

FloorRating

WallRating

FirstTenancy

AdjoiningTenancy/space

SOU–allspaces

SOU–allspacesexcept
thosebelow

Rw≥45

Laundry,kitchen

RW≥45andof

discontinuous
construction

SOU–allspaces

Plantroom,utilities
room,bathroom,sanitary
compartment(butnotan
associatedensuite)

Rw≥45

Rw≥45

Notes: Discontinuous construction refers to walls having a minimum 20 mm gap between separate leaves and
with no mechanical linkages between wall leaves except at the wall periphery, such as wall top plates.

Whereawallisrequiredtohavesoundinsulationhasafloorabove,thewallmustcontinuetothe
undersideofthefloorabove,ortheceilingmustprovidetheequivalentsoundinsulationrequired
forthewall.(Professionaladviceshouldbesoughttoupgradeceilingtotherequiredwallsound
insulation).

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 10


2.3
Refer to:
BCA F5.6.


Services

Ifaduct,soil,wasteorwatersupplypipeservesorpassesthroughmorethanonedwelling,theduct
orpipemustbeseparatedfromtheroomsofthedwellingsbyconstructionwithanRw+Ctrnotless
than:
• 40ifitisadjacenttolivingareasinadwelling;or
• 25ifitisadjacenttoakitchenorbathroom.
Itisalsorequiredwhereaductorpipeislocatedwithawallorceilingcavity.
2.4

The Next Step

HavingusedthepreviousinformationtoobtainanunderstandingoftheBCA’sminimumsoundinsulationrequirements,thenextstepistoeither:
• gotoStep3tofindoutaboutimprovingand/orupgradingsoundperformance(e.g.beyond
minimumBCArequirements);or
• gotoStep5toselecttimber-framedconstructionthatwillcomplywithminimumBCAsound
requirements.
Oncesound-insulationrequirementsaresatisfied,thenextStepisStep4FireDesignRequirements.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 11


3
Quiet dwellings
command premium
prices, so it may pay
to exceed minimum

sound performance
standards.

Step 3 – Improve and Upgrade
Sound Performance
Soundperformancecanoftenbeimprovedbysimpleattentiontotheformandspatial
arrangementofthebuildingdesign.Attentiontoflankingnoiserepresentsanotherimportant
meansofimprovingsoundperformance.Inaddition,manyendusersofdwellingswant
highersoundperformancethantheminimumlevelsrequiredintheBCA.Asaresultofthese
issues,thisStepintheGuidefocusesonwaystoimproveandupgradesoundperformance.
3.1

Attention to Building Design to Reduce Sound Transmission

Aspectsoftheformandspatialdesignofabuildingthatcanbeadaptedtoimprovesound
performancearedealtwithunderthefollowingheadings.
3.1.1

Room Layout

Checkthattheroomlayoutisbeneficialratherthandetrimentaltosoundtransmission.Servicerooms
includingbathrooms,laundriesandkitchenscreateextrasoundcomparedtolivingroomsand
bedrooms.Forinstance,watermovementthroughplumbingpipesandthevibrationfromwashing
machinesanddishwasherscreatesoundproblems.Itisthereforebestfortheserviceroomsinone
dwellingtobackontothesametypeofroomsinanadjoiningdwelling(butnotbackontohabitable
rooms).Also,trytoensureentrancestodwellingsareanappropriatedistancefromadjacentunits
(Figure6).
3.1.2

Windows and doors

can thwart the best
wall systems, but
there are smart
acoustic solutions.

Windows

Windowsnormallyhavelowersoundinsulationthanthewallstheyarelocatedwithin.Asaresult,
highlysound-ratedboundingwallsystemsmaybecomeineffectivebyvirtueofnearbypoorlysound
ratedwindows.Forimprovement,consideroneormoreofthefollowing:
• Usethickerglassordoubleglazing.
• Usefixedglazinginlieuofopeningwindows.(Thismayalsorequiresound-insulatedventilation.)
• Locatewindowssothattheydonotfacenoisyareas.
• ProvideadequateseparationbetweenwindowsinadjoiningSOUs.
• Reducetheareaofwindowsinthefacade.
• Fillvoidsbetweenthewallframeandwindowframewithanappropriateacousticsealant.
• Useacousticsealingstrips/gasketsaroundtheedgesofopen-ablesashes.
3.1.3

Doors

Aswithwindows,doorstendtobetheweaklinkinsoundratedwallsystems.Wheresound-control
isdesired,solidcoredoorsshouldbeusedandshouldbetreatedwithsoftacousticgasketsat
interfaceswithdoorjambs.Thresholdclosersatthebottomofthedoororairsealswillalsoreduce
soundtransmission.Inmostcases,thesoundratingrequiredtobemetwillrequiretheuseofgaskets
andseals.Slidingdoorsshouldbeavoidedwhereoptimumsound-controlisdesired.
3.1.4

Services


Thelocationanddetailingofservicesaretwoofthemostimportantconsiderationsincontrolling
soundtransmissioninresidentialbuildings.
Generally,servicesandservicepenetrationsshouldnotbelocatedonsound-insulatedwallsbetween
SOUsbutratheroninternalwallsordedicatedsoundresistantserviceshafts.Inallinstances,service
pipesshouldbelocatedawayfromnoisesensitivepartsofthedwellingsuchasbedrooms(Figure6).

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 12


✗ Dissimilar
rooms adjoin
located
✓ Bedrooms
away from walls

✗ Bad
vibration
✗ Dissimilar
rooms adjoin
BED

BATH

LDY

BED

BED

KITCHEN

Flanking noise (that
which passes around
walls and floors) can
turn up where it's
neither wanted nor
expected.

BED

BED

BATH

LDY

LDY

LIVING

BED

DECK

KITCHEN
LIVING

LIVING


DECK

BATH

KITCHEN

LIVING

DECK

between units and
public areas

rooms
✓ Similar
adjoin

from
washing
machine

DECK

KITCHEN
BED
LDY

duct
✗ Service
located near


BATH

bedroom

duct located
✗ Service
in wall between units

✗

Bedroom
located
adjacent to
stairs

✗ Entry doors opposite

✓ Service
duct

located
away from
bedrooms

BED

Ensure rooms of
✓ Note:
similar use are located


adjacent to each other,
i.e. use mirror image
floor plans in adjacent
units.

Figure 6: Good and bad sound design practices in building layout – plan view.

3.2

Addressing Flanking Noise

Theabilitytoinsulateagainstsoundmovingfromonedwellingtothenextisdependentnotonlyon
insulatingindividualwallandfloorelements,butalsoonstoppingnoisefromjumpingortransferring
fromonebuildingelementtothenext,orworsestill,movingthroughthebuildinginanuncontrolled
way.Asaresult,theeffectivenessofsound-insulatedconstructionisconcurrentlydependenton
addressingflankingnoise.Flankingnoisereferstosoundpassingaroundratherthanthroughwall/
floorelements,thuscausingsoundtounexpectedlymanifestitselfinunwantedplaces.
ThemainflankingroutesaroundwallandfloorelementsareshowninFigure7.Theseroutes
particularlyapplytowallsandfloorsseparatingSOUsbutmayalsoapplytoexternalwallsandin
someinstancesinternalwalls(withinSOUs)aswell.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 13


Airborne
sound
path


Airborne
sound
path
Flanking
sound
path

Figure 7: Flanking and airborne noise pathways – elevation view.

Solutions to flanking
noise may need to
be as oblique as the
problem.

TherearenominimumrequirementsaddressingflankingnoiseintheBCA’sDeemedtoSatisfy
Provisions,thoughthereisanonusondesignersandbuilderstoaddressflankingnoiseinorderto
ensurethatlaboratory-testedwallandfloorelementsperformtotheirfullpotentialinthefield.
IndevelopingthisGuideconsiderationwasgiventoreducingtheflankingnoisepathswherever
possible.Insomeinstances,limitsonwhatcouldbeachievedinreducingflankingwereimposed
becauseoftheiraffectonfireandstructuralintegrity.ThereforedetailsgiveninthisGuidearethe
conclusionofcarefulthought,takingintoaccountalltheseissues.Eventhoughdirectreferenceto
reducingflankingnoisehasnotbeenmade,manyofthedetailsincorporateelementswithinthem.
Anexampleofreducingflankingnoisecanbeseeninthestandarddetailforfloorjoistandflooring
overboundingwallswherethejoistandflooringarenotcontinuous.Thishasbeendonepurelyto
reduceflankingnoiseandhasnootherpurpose(Figure8).
Fire- and
sound-rated linings
Timber packers


Flexible fire-grade
sealant

Discontinuous
flooring sheet

Floor joists parallel
to separating wall

Steel furring channels set
on noise-resistant mounts

Double joists

Fire- and
sound-rated linings

Figure 8: Discontinuous floor joist and floor sheeting – elevation view.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 14


Therearetwomainapproachesusedforaddressingflankingnoiseintimber-framedbuildings:
• Limitthenoisegettingintowall/floorelemente.g.carpet,floatingfloors(Figure9).
• Limittheabilityofthenoisetomigratefromoneelementtoanothere.g.dampeningandisolationat
junctionsbetweenelements(Figure8).
45 mm thick
concrete layer


Acoustic-isolating pad

Sheet flooring

Timber floor
joists

Steel furring
channel at 600 mm
max. centres

Noise-isolating
ceiling clips

Fire- and
sound-rated linings

Figure 9: Acoustic isolating pad to reduce flanking noise.

Inadditiontothestrategiesabove,timber-framedconstructiondetailsorientatedtoimprovingflanking
soundareprovidedinSection5.3,andinclude:
• platformflooringdiscontinuousoverdoublestudwalls;
• cavitieswithinsoundratedelementsblockedortravelpathincreasedtoreducenoise;
• discontinuouselementsatwalls,floorsandceilings;and
• introducedisolatingelements,e.gresilientmatsorbrackets.
3.3
Where user tastes
(e.g. for powerful
home entertainment

units) outpace BCA
standards, you
must think outside
the square.

Strategies for Upgrading Sound Performance in Construction

Buildingoccupantsoftenwanthighersoundperformancethantheminimumrequirementsinthe
BCA.Thisisespeciallythecaseforimpactsoundandtherelatedissueofvibrationwhichcomes
fromfootsteps,watermovementthroughpipes,waterhammerandanysourceofvibrationincluding
washingmachines,airconditioningunitsanddishwashers.Otherscenariosnotdealtwithinthe
BCAincludeacousticrequirementsforhomeentertainmentareas,noisetransferwithinadwelling
andnoisefromoutsidethebuilding(e.g.busyroads,trains,aircraftnoise).Optionsforupgrading
typicalconstructionareprovidedbelow.Usingacombinationofoptionsismorelikelytogivebest
performance.
Isolatingonesideofaboundingconstructionfromtheother(e.g.usingdoublestudcavity
wallconstruction).Thisisalsoknownasdecouplingandcanbeusefulinreducingbothairborneand
impactsound.Ofnote,itservestolimitnoisevibrationfromonesideoftheelementtotheother.
Avoidingrigidconnectionsbetweentheopposingsidesofisolated(decoupled)elements.
Thislimitstheoccurrenceofsoundbridgesthatwouldotherwiseallowsoundtotransmitfromone
sidetotheother.Ifrequiredforstructuralstability,sound-resilientconnectorsshouldbeusedand
shouldgenerallyonlybeusedatfloororceilinglevel.
Usingabsorptivematerialstofillwallandfloorcavities(cellulosefibre,glassfibreormineral
wool)canreduceairbornesoundtransmission.
Sealingsoundleaksattheperipheryofwallandfloorelementsorwherepenetrationsaremadefor
electricalandplumbingservices.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 15



3.3.1

Walls

Extramassonthewalls–theadditionofmassisasimpleyetimportantmeansofimprovingsound
performanceintimber-framedconstruction.Initssimplestform,thisinvolvesaddingextralayersof
materialsuchasplasterboardtothesoundratedwallsystem.
Usea90mmratherthan70mmwallstuds–Thewiderthewall,thebetteritssoundperformance.
ThisisparticularlythecasewheretryingtoimproveCrtscores(beingthemodificationfactorforlow
frequencybassnoiseappliedtoRwscores).Thesimplestmeansofdoingthisistouse90mmwide
studsinsteadof70mmwidestudsinadoublestudwallsystem.
Upgradebattsinthewall/floor–Therearemanydifferenttypesandgradesofinsulationbatts
availableinthemarketplace.Soundinsulationspecificbattsarebestandinaddition,highdensity
materialstendtooutperformlowdensitymaterials.Thisisthecaseuptoadensityof60kg/m2,above
thisthedensityhasaminoreffect.Itisrecommendedthatataminimumof10kg/m2beused.
3.3.2
Sound reduction
needn't be high tech.
Adding mass is a
simple yet highly
effective measure.

Floors

Extramassontheceilings–theadditionofmassisasimpleyetimportantmeansofimproving
soundperformanceintimber-framedconstruction.Atitssimplestmanifestation,thisinvolvesadding
extralayersofmaterialsuchasplasterboardtothesoundratedceilingsystem.
3.4


The Next Step

ThestrategiesandmethodsshowninthisStepoftheGuidemayinvolvespecialistproprietary
systemsthatgobeyondthescopeofthispublication.Asaresult,thenextstepistoeither:
• gotoproprietarysystemsuppliersandaskforadviceonhowtointegratetheirsystemswiththose
discussedinthisGuide.Aspartofthis,caremustbetakentoensurethatthefireandsound
performanceofsystemsinthisGuidearenotcompromisedinanyway;
• gotoStep4tofindoutaboutfire-resistingconstructionrequirementssothattheserequirements
canbeconsideredintandemwithsoundrequirementsbeforeselectingtheappropriatetimberframedconstructioninStep5;or
• gotoStep5toselecttimber-framedconstructionthatwillcomplywithminimumBCAsoundandfire
requirements.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 16


4

Step 4 – Define BCA Fire-Design
Requirements
Designingfire-resistantconstructioninvolvesaprocessofunderstandinghowtheBCA’s
PerformanceRequirementstranslateintothemoreobjectiveandmeasurableDeemedto
SatisfyProvisions,thenselectingtimber-framedconstructionsystemsthatsuitsthese
requirements.
4.1

Refer to:
BCA CP1 – CP9.


Utilising the Deemed to Satisfy Provisions for Fire Design

PartCoftheBuildingCodeofAustraliaPerformanceRequirementsareconcernedwithsafeguarding
peoplewhenafireinabuildingoccurs.Specificattentionisgiventoevacuatingoccupants,facilitating
theactivitiesofemergencyservicespersonnel,avoidingthespreadoffirebetweenbuildings,and
protectingotherpropertyfromphysicaldamagecausedbystructuralfailureofthebuildingasaresult
offire.
DeemedtoSatisfyProvisionsthatmeettheabovePerformanceRequirementsaredetailedintheBCA
under:
• PartC1–Fire-resistanceandstability.
• PartC2–Compartmentalisationandseparation.
• PartC3–Protectionofopenings.
ThesePartsdealwithawiderangeofissuesbutitisonlythefire-resistanceofspecificbuilding
elements(e.g.wallandfloor/ceilingelements)thataredealtwithinthisGuide,astheseelementscan
beoftimber-framedconstruction.Tothisend,onlyrelevantclausesfromPartsC1,C2andC3are
discussedinmoredetailbelow.Tohelpusersunderstandthefullrangeofissuescontainedinthese
Parts,achecklistisprovidedinAppendixB.
4.2

Refer to:
BCA C1.2
BCA C1.5
BCA C1.1.

Determining the Type of Construction Required

Giventhepreviousdiscussion,themainissueofinterestfortimber-framedconstructionrelatesto
determiningtheTypeofConstruction,asdefinedintheBCA,requiredtoresistfireforagivenbuilding.
Theissuesinvolvedaredescribedbelow:

• Calculatethenumberof'riseinstoreys'ofthebuilding(Note:ThisisaBCAtermandreferenceto
BCAC1.2isrecommended)
• TakeintoaccountconcessionsfortwostoreyClass2,3and9cbuildings.Relevantfactorsinclude
disregardingnon-combustiblerequirements,numberofbuildingexits,accesstoopenspaceand
theuseofsprinklersystems(BCAC1.5)andcompartmentsize(9conly).
• DetermineiftheconstructionisTypeA,BorCconstruction(BCAC1.1):
–TypeAprovidesthehighestlevelofpassiveprotectione.g.structuralelementsmustwithstand
burnoutofthebuildingcontents.
–TypeBprovideslowerpassiveprotectione.g.lessofthestructuremustbeabletowithstand
burnoutofthecontents.
–TypeCprovidesthelowestpassivefire-resistancee.g.onlysomeelementshavespecifiedfireresistanceintendedtomainlyrestricthorizontalspreadoffiretoadjoiningdwellings.

The chart on the next
page will help you
plot your course.

AcharttoassistselectionoftheappropriatetypeofconstructionisshowninFigure10.Italsoallows
userstodetermineifatimber-framedbuildingsolutionispossibleundertheDeemedtoSatisfy
Provisions,orifanAlternativeSolutionwillbenecessary.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 17


TYPE OF
RESIDENCE

Flats & apartment
buildings containing

2 or more dwellings

Residential portions of hotels,
motels, guesthouses, aged
and retirement homes etc

SEPARATION

Units side-by-side only

Units may be
side-by-side and above
or below each other

BUILDING
CLASS

CLASS 1 BUILDING
(not detailed in this guide)

CLASS 2
BUILDING

1

NUMBER OF
STOREYS

3


EXITS OR
SPRINKLER
SYSTEM

BUILDING
CLASS

Each
dwelling
provided
with egress
in two
directions
or own
direct
access to
road or
open space

Class 2
Type C

Class 2
Type A

1

2

BCA

Alternative
Solution

2

3

Each
dwelling
provided
with egress
in two
directions
or own
direct
access to
road or
open space

One
shared
exit

Class 2
Type B

1

Masonry
ry

or
concrete
garage to
ground
floor

One
shared
exit

CLASS 9c
BUILDING

CLASS 3
BUILDING

4

2

Residential aged
care facilities

C
Class
3
TType C

One
shared

exit

BCA
Alternative
Solution

3

Building
protected
by
complying
sprinkler
system and
max. floor
area of
3000 m2 or
max.
volume of
18000 m3

C
Class
9c
TType C

BCA
Alternative
Solution


Figure 10: Determining the type of construction and applicability of Deemed to Satisfy Provisions.

Refer to:
BCA Spec. C1.1.

FRL = Fire
Resistance Level.

4.3

Determining Fire Resistance Levels for Building Elements

HavingdeterminedthecorrectTypeofConstructionforthebuilding,itisnowpossibletodeterminethe
FireResistanceLevelsrequiredforvariouswall,floor,ceilingandotherbuildingelements(Note:Thisis
possibleusingspecificationC1.1ascalledupintheBCA’sDeemedtoSatisfyProvisions).
AFireResistanceLevel(FRL)expressestheminimumamountoftime(inminutes)thatabuilding
componentmustresistafireasdefinedbythreeseparateelements:
• Structuraladequacy–abilitytowithstandloads.
• Integrity–intermsofcontainingsmoke,flamesandgases.
• Insulation–intermsoflimitingthetemperatureononesideoftheelementgettingthroughtothe
otherside.
AnexampleofthewaythataFireResistanceLevelisexpressedis:60/60/60.Anotherexamplewhere
afireratingisnotrequiredforallelementsis:–/60/–.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 18


DeemedtoSatisfyFireResistanceLevelsforbuildingelementsinClass2and3,TypeA,BandC

constructionareprovidedinFigures11,12and13respectively.Class9c,TypeCisfoundinFigure
14.ThesefiguresrepresentaninterpretedversionofinformationcontainedinBCASpecificationC1.1.
Ininterpretingthesefigurescareshouldbetakentorecognisethevarietyofdifferentwall,floorand
ceilingsituationsinvolved.Ofnote,thisincludestheselectiveneedforroofvoidwallsthatrestrictthe
passageoffirefromoneSOUtoanotherthroughtheroofvoid.AnalternativewhichisrelevanttoType
AconstructionistheuseofaResistanttoIncipientSpreadofFlameceilingwhichaimstopreventthe
spreadofflamebeforeitgetsintotheroofvoid.
OncerelevantFireResistanceLevelshavebeenestablishedforallrelevantelementsitisthenpossible
toselecttimber-framedconstructionthatwillmeetthechosenFireResistanceLevelsrequirements
fromSection5.Inaddition,itisimportanttoconsidermorespecialisedelementsasdealtwithunder
thefollowingSection5.4.
LOADBEARING
OADBEARING EXTERNAL W
WALLS
When tested/certified from outsideDistance from fire source feature
Less then 1.5 m........... FRL 90/90/90
1.5 to less then 3.0 m.. FRL 90/60/60
3.0 m or more.............. FRL 90/60/30

INTERNAL W
WALLS
bounding hallways, sole occupancy
units and the like
Loadbearing................FRL 90/90/90
Non-loadbearing .........FRL – /60/60
Service shafts
Loadbearing................FRL 90/90/90
Non-loadbearing .........FRL – /90/90

Store

Not an
SOU

SOU

SOU

SOU

SOU

SOU

SOU

SOU

SOU

SOU

SOU

FLOORS – FRL 90/90/90
(no impact sound-rating required
by BCA but it is recommended).

Store
Not an
SOU


LOWER STOREY (ground floor)
To accommodate car parking
only and to be masonry/concrete
construction FRL 90/90/90

ROOF
No FRL is required where
ceiling has 60 minute
resistance to incipient spread
of fire or internal fire rated
walls bounding units,
stairways, hallways, etc extended to underside of
non-combustible roofing
INTERNAL NON-LOADBERING
WALLS wholly within a unit no
W
FRL or Rw is required

Internal loadbearing walls
and beams (within a unit)
FRL 90/ – / –

No FRL required where under
floor is not a storey and does
not accommodate vehicles
SOU = Sole Occupancy Unit

Figure 11a: Type A Construction Deemed to Satisfy Requirements – without sprinklers (must have smoke alarms).


LOADBEARING
OADBEARING EXTERNAL W
WALLS
When tested/certified from outsideDistance from fire source feature
From Outside
Less then 1.5 m...........FRL 90/90/90
1.5 to less then 3.0 m..FRL 90/60/60
3.0 m or more..............FRL 90/60/30

From Inside
FRL 60/60/60
FRL 60/60/60
FRL 60/60/30

INTERNAL W
WALLS
Bounding hallways, sole occupancy
units, service shafts and stairways
Loadbearing – FRL 60/60/60
Non-loadbearing – No FRL is required
where lined with 13 mm plasterboard
and walls extend to floor above or
ceiling with 60 minutes resistance to
incipent spread of fire
ROOF
No FRL is required where
ceiling has 60 minutes
resistance to incipient spread
of fire where internal fire rated
walls extend to the underside

of non-combustable roofing

Store
Not an
SOU

SOU

SOU

SOU

SOU

SOU

SOU

SOU

SOU

SOU

FLOORS – FRL 90/90/90, Rw 45
(no impact sound-rating required
by BCA but it is recommended).

SOU


Store
Not an
SOU

INTERNAL NON-LOADBERING
WALLS – wholly within a unit
W
no FRL or Rw is required

INTERNAL LOADBEARING
WALLS COLUMNS and
W
BEAMS (within a unit)
FRL 90/ – / –
SOU = Sole Occupancy Unit

Figure 11b: Type A Construction Deemed to Satisfy Requirements – with sprinklers and smoke alarms.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 19


LOADBEARING
OADBEARING EXTERNAL W
WALLS
Distance from fire source feature
Less then 1.5 m........... FRL 90/90/90
1.5 to less then 3.0 m.. FRL 90/60/30
3.0 to less then 9.0 m.. FRL 90/60/30

9.0 to less then 18.0 m FRL 90/30/ –
18.0 m or more............ FRL – / – / –

Store
Not an
SOU

SOU

SOU

SOU

FLOORS – FRL 30/30/30

INTERNAL W
WALLS
bounding sole occupancy units,
corridors, hallways and like:
Loadbearing............... FRL 60/60/60
Non-loadbearing - ..... FRL – /60/60
Service shafts............. No FRL required

SOU

SOU

Store
Not an
SOU

SOU

No FRL required for floor where
under floor is not a storey and
does not accommodate vehicles

SOU = Sole Occupancy Unit
ROOF SP
SPACE
No FRL dividing walls are
required where ceiling has
60 minutes resistance to
incipient spread of fire.
Where ceiling is not RISF
rated FRL walls to be
extended to the underside
of non-combustable
roofing
INTERNAL
NON-LOADBERING
OADBERING W
WALLS
wholly within a unit no FRL
or Rw is required
INTERNAL LOADBEARING
WALLS COLUMNS AND
W
BEAMS (within a unit)
FRL 90/ – / –


Figure 12a: Type B Construction Deemed to Satisfy Requirements – without sprinklers (must have smoke
alarms).

LOADBEARING
OADBEARING EXTERNAL W
WALLS
when tested/certified from outside
Distance from fire source feature
From Outside
Less then 1.5 m............FRL 90/90/90
1.5 to less then 3.0 m...FRL 90/60/30
3.0 to less then 9.0 m...FRL 90/60/30
9.0 to less then 18.0 m.FRL 90/30/ –
18.0 m or more.............FRL – / – / –

Store
Not an
SOU

SOU

SOU

SOU

SOU = Sole Occupancy Unit

From Inside
FRL 60/60/60
FRL 60/60/30

FRL 60/30/30
FRL 60/30/ –
FRL – / – / –

INTERNAL W
WALLS
Bounding sole occupancy units,
corridors, hallways and like:
Loadbearing – FRL 60/60/60
Non-loadbearing – No FRL required
where lined with 13 mm plasterboard
and walls extend to ceiling with 60
minutes resistance to incipient spread of

SOU

SOU

FLOORS
FRL 30/30/30 or underside
of floor to be lined with fire
protective covering

Store
Not an
SOU
SOU

ROOF
No FRL where ceiling has

60 minutes resistance to
incipient spread of fire or
where internal fire rated
walls extend to the
underside of
non-combustable roofing
INTERNAL
NON-LOADBERING
OADBERING W
WALLS
wholly within a unit no FRL
or Rw is required
INTERNAL LOADBEARING
WALLS COLUMNS and
W
BEAMS (within a unit)
FRL 60/ – / –

Figure 12b: Type B Construction Deemed to Satisfy Requirements – with sprinklers and smoke alarms.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 20


For distance to fire source feature
less then 1.5 m external wall may
be timber framed with outer wall
having an FRL 90/90/90


SOU = Sole Occupancy Unit
ROOF
No FRL where ceiling has 60
minutes resistance to
incipient spread of fire or
where internal fire rated walls
extend to the underside of
non-combustible roofing

INTERNAL W
WALLS
FRL 60/60/60 (FRL –/60/60 for
non-loadbearing walls

For distance 1.5 m or greater NO
FRL requirement

SOU

SOU

SOU

SOU

SOU

SOU

SOU


SOU

INTERNAL
NON-LOADBEARING
WALLS wholly within a unit.
W
No FRL requirements
provided walls are timber
framed and lined with
plasterboard or fibre cement
INTERNAL LOAD BEARING
COLUMNS separating storeys
or in a space for vehicles to
have FRL 30/ – / – or be
covered with fire protective
material

NOTE: Garage (not
a storeroom) may
accommodate up
to 3 vehicles before
it is included as a
storey

Timber floors separating
storeys or above motor
vehicles to have FRL
30/30/30 or have a fire
protective covering on

the underside

No fire resistance required
where under floor is not a
storey or does not
accommodate vehicles

EGRESS REQUIREMENTS
Exits at either end of the building
shall not be closer than 9 m or
more than 45 m apart or each
SOU to have its own direct access
to a road or an open space

Figure 13: Type C Construction Deemed to Satisfy Requirements.

SOU = Sole Occupancy Unit

EXTERNAL W
WALLS
When tested/certified from outside
Distance from fire feature

INTERNAL W
WALLS
bounding a communal
stair case FRL 60/60/60

Less then 1.5 m...........FRL 90/90/90
1.5 m to less then 3 m FRL 90/60/60

3.0 m or more..............FRL – / – / –

INTERNAL W
WALLS bounding
sole occupancy units,
corridors, hallways, etc.
Loadbearing FRL – / – / –

ROOF
No FRL
required
SOU

SOU

SOU

SOU

SOU

SOU

SOU

SOU

SPRINKLERS AND
SMOKE ALARMS are
required throughout

the building

FLOORS OVER
VER CARP
CARPARKS AND
STORAGE – FRL 30/30/30 or
underside of the floor to be lined
with fire protective coverings

INTERNAL LOAD BEARING
WALLS COLUMNS and
W
BEAMS (within a unit)
FRL – / – /–

Figure 14: Class 9c, Type C Deemed to Satisfy Requirements.

#02 • Timber-framed Construction for Multi-residential Buildings Class 2, 3 & 9c

Page 21


4.3.1
Refer to:
BCA Spec C1.1, 3.10
and 4.3.

Given the recent
influx of inferior
insulation, it's vital

to confirm noncombustibility.
Some products
create a fire hazard!

Non-Combustibility Concession

TheBCASpecificationC1.1forTypeAandBconstructionrequiresthatexternalwalls,common
andnon-loadbearingfire-resistingwallandshaftstobebuiltfromnon-combustiblematerialand
loadbearinginternalandfirewallstobebuiltfromconcreteormasonry.SpecificationC1.1Clause3.10
and4.3providesaconcessiontotheserequirementsaslongasnon-combustibleinsulationisused.
Non-combustibleinsulationproductsaremainlymineralwoolproductsbutconfirmationisrequired
fromthemanufacturer.
4.3.2

Sprinklers

ThereisnorequirementtousesprinklersinClass2and3buildingsaslongastheeffectiveheightof
thebuildingisnotmorethan25m.Ifsprinklersareinstalled,thereisaconcessionsforTypeAandB
FireResistanceLevelforcertainelements.
ForClass9cbuildingsprinklersarerequiredthroughoutthebuilding.
4.4

Special Fire Issues

InconstructingClass2,3and9ctimber-framedbuildings,specialissuesariseasbuildingsbecome
largerandmorecomplicated.AlthoughthisGuidedoesnotattempttoprovideinformationtosuit
allcircumstances,informationisprovidedwherethereisrelevancetotimber-framedconstruction
practices.AsummaryoffireissuescoveredinthisGuideisfoundinAppendixB.
4.4.1


Refer to:
BCA C2.14 and
Spec C2.5 2 & 3.

Smoke–Proof Walls

ForClass2and3buildings,theBCArequiresthatpubliccorridorsgreaterthan40mlongbe
dividedbysmoke-proofwallsatintervalsofnotmorethan40m.Thesewallsmustbebuiltfromnoncombustiblematerialsandextendtothefloorabove,roofcoveringorResistanttoIncipientSpreadof
Fireceiling.
ForClass9cbuildings,smoke-proofwallsarerequiredtorestrictopenareastonotmorethan500m2
and/orsurroundancillaryuseareassuchasakitchen,laundryorstoragerooms.Thewallsare
requiredtobeatleastsheetedononesidewithanon-combustiblelining.Ifplasterboardisuseditis
tobeatleast13mmthick.
Detailsshowinghowtoconstructsmoke-proofwallsoutoftimber-framedconstructionareshownlater
inthisGuideunderSection5.10.
4.4.2

Shafts

ShaftsusedinTypeAbuildingsforlifts,ventilation,pipes,garbageorsimilarpurposearerequiredto
befire-resistingtoaFireResistanceLevelsof90/90/90or-/90/90.ForTypeB&Cbuildings,shafts
shouldhavethesameFireResistanceLevelsastheelementtheypenetrate.
Refer to:
BCA Spec C3.1(c)
and C4.1 (d).

Shaftsmustalsobeenclosedatthetopandthebottomwithafloor/ceilingsystemofthesameFire
ResistanceLevelsasthewalls,exceptwherethetopoftheshaftisextendedbeyondtheroof,orthe
bottomoftheshaftislaidontheground.
TheshaftisalsorequiredtobesoundratedifitpassesthroughmorethanoneSOUandmusthave

aRw+Ctrof40iftheadjacentroomishabitableandRw+Ctrof25ifitiskitchenornon-habitable
room.
Detailsshowinghowtoconstructshaftsintimber-framedconstructionareshownlaterinthisGuide
underSection5.6.

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4.4.3

Complex Roof Framing Intersecting Fire-Rated Walls

WherearoofvoidmayallowafiretopassfromoneSOUtoanother,theBCArequiresthata
fire-resistingwallextendtotheundersideofanon-combustibleroofandnottobecrossedby
combustibleconstructionexceptforamaximumof75x50mmroofbattens.Formanysituationsthis
isnotpracticalsuchaswherewallsintersectvalleysorhipsends.Inthesecases,aceilingwhichis
ResistanttoIncipientSpreadofFireisoftenapreferredoption,seeSection5.5ofthisGuide.
4.4.4
Refer to:
BCA C2.6.

Vertical Separation of Openings in External Walls

Toreducethechanceofafirespreadingfromonefloortothenextviatheexternalwall,thereisaneed
intheBCAtoaddresstheverticalseparationofopenings.ThisonlyappliestoTypeAconstruction,as
thereisnorequirementforTypeBandCconstruction.
InTypeAconstruction,wherethereisanopeningdirectlyorwithin450mm(measuredhorizontally)of
anotheropeninginthestoreybelow,andthebuildingisnotfittedwithautomaticsprinklers,theBCA

requirestheseopeningstobeprotected(Figure15).
Protectioncanbeachievedbyaspandrelwhichisnotlessthan900mminheightbetweenthetwo
openingsandnotlessthan600mmabovetheupperfloorsurface.ThespandrelmusthaveaFire
ResistanceLevelof60/60/60,whichinmostcasesistherequirementoftheexternalwall.
Alternatively,horizontalconstructionprojectingatleast1,100mmfromtheexternalfaceofthewall
andextendingnotlessthan450mmbeyondtheopening,eithersideofthewall,isrequired.Againthe
constructionmusthaveanFireResistanceLevelsof60/60/60.
Detailsshowinghowtoconstructthetwooptionsintimber-framedconstructionaregiveninthisGuide
underSection5.7.

900 mm
min.
Spandrel

600 mm
min.

900 mm
min.

450 mm
min.
450 mm
min.
1100 mm
min.

Figure 15: Required dimensions for spandrel panels.

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4.4.5
Refer to:
BCA D1.3.

Fire- and Non-Fire-Isolated Stairs

Non-fire-isolatedstairsarerequiredforthefollowingbuildingclassifications:
• Class2,TypeA,BandC–wherenotmorethanthreeconsecutivestoreysareconnected
• Class3,TypeC–wherenotmorethantwoconsecutivestoreysareconnected.
• Class9c,TypeC–wherenotmorethantwoconsecutivestoreysareconnected.
OneextrastoreyisallowedforClass2and3iftheextrastoreyisforuseasagarageorhascomplying
sprinklersinstalledortheegressoraccessisseparatedfromtheextrastoreybyfire-ratedconstruction
applicablefortheconstructiontype.

Section 5.6 shows
how to ensure
penetrations
don't compromise
fire-rated walls.

AsthisGuideaddressesonlyBCADeemedtoSatisfycategoriesofbuildingsand'riseinstoreys'
wheretimberframingcanbeused,andthisrangeofbuildingsdoesnotrequireFire-IsolatedStairways
andRamps,constructioninformationonFire-isolatedStairwaysandRampsisnotaddressedinthis
Guide.
Fortherangeof'buildingtypes'and'riseinstorey'thisGuideconsiders,stairwaysorrampsthatare
requiredforegressandaccesstobeNon-Fire-IsolatedStairwaysandRamps.Stairscontainedentirely

withintheSoleOccupancyUnit,orthatdonotformapartoftheescapepathforexitingaunitinan
emergency,havenofireratingrequirement.DetailsshowinghowtoconstructtheNon-Fire-Isolated
StairwaysandrampsareshownlaterinthisGuideunderSection5.8.
4.4.6

Refer to:
BCA Spec C3.15.

Services Penetrating Fire-Resistant Elements

TheBCArequiresthatwhereservicessuchaspipes,ductsandelectricalcablesthatpenetrateafireratedwall,floororceiling,suchpenetrationdoesnotaffecttheperformanceofthebuildingelement.
DetailsshowinghowtomeetthisrequirementareshownlaterinSection5.6.
4.4.7

Refer to:
BCA Spec. C1.8.

Lightweight Construction

TheBCArequireselementsthathaveaFireResistanceLevels,orthatformalift,stairshaft,
anexternalwallboundingapubliccorridor,non-fire-isolatedstairwayorramp,tocomplywith
SpecificationC1.8,iftheyaremadeoutoflightweightmaterialssuchastimberframingand
plasterboard.SpecificationC1.8isastructuraltestforlightweightconstruction,andinmostpartsis
directlyrelatedtotheperformanceoftheliningsused.Manufacturersofliningmaterialshouldbeable
toprovideappropriateinformationoncompliancetothisrequirement.
4.5

The Next Step

Havingusedthisinformationtoobtainastrongunderstandingoffire-resistantconstruction,thenext

stepistogotoStep5–SelectingTimber-FramedConstructionthatwillcomplywithminimumBCA
fire-resistingconstructionrequirements.

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5

Step 5 – Select Sound- and
Fire-Rated Timber Construction
Systems
ThisStepfocusesonmatchingDeemedtoSatisfysound-insulationlevels(RW+Ctr,Ln,w
+CI),FireResistanceLevels(FRLs)andothernecessaryrequirementswithappropriate
timber-framedconstruction.Thecommentarybeginsbyexplainingkeyprinciplesused
intimber-framedconstructiontoaddresssoundinsulationandfiresafetyneeds.These
principlesarethenpresentedintheformofintegratedsystems,e.g.timber-framedwall,floor
andceilingsystems.Importantly,constructiondetailsareprovidedforeachsysteminterms
offire/soundratedjunctionsbetweenelements,penetrationsinelements,stairconstruction
details,treatmentofserviceshafts,balconiesandsimilarsituations.
5.1

Principles for Achieving Fire Resistance Levels in Timber-Framed Construction

Fire-gradelinings(seeAppendixDfordefinition)providetheprimarysourceofprotectiontotimber
framing,andgenerallythegreaterthenumberoflayers,thegreatertheresistancetofire.Additional
measures,asdiscussedinthefollowingparagraphs,arerequiredatweakspotsorbreaksinthe
fire-gradeliningsthatoccuratintersectionsbetweenwall,floorandceilingelements.Cornerlapsand
exposededgesinliningsheetspresentareaswhereattentionisneeded.Extraconsiderationisalso

neededatpenetrations,openingsandprotrusions.
In some situations,
solid timber can
equate to fire-grade
linings.

Duetothesequencingoftradesinlightweightbuildings,itisnotalwayspossibletoprovidecomplete
coveringwiththefire-gradeliningsasframingelementsoftengetintheway.Solidtimbercanbeused
asanequivalenttofire-gradeliningsinthesesituationsandthisismainlyusedwhereliningsstopat
junctionsbetweenwalland/orfloorelements.Atthesejunctions,thewidthofthetimberframeworkis
unprotectedbytheliningsandsoextrastuds,platesorjoistsareusedtoprovidefire-resistance.This
ispossiblebecausetimberofacertainthicknessformsaninsulatingcharlayerasitburns.Thishelps
protectandslowtheburningprocessfortheremainingtimberthickness.Asaresult,itispossible
topredictablycalculateanddeterminehowlongthetimberjointwilllastinafire.Thoughthisvaries
accordingtotimberdensity,ingeneral,themorepiecesofsolidtimberaddedtothejoint,thelonger
thejointwilllast.Forhigherfire-resistance,thejointisreinforcedwithalight-gaugemetalangle.
Commonlocationswheresolid-timberblocksareusedincludewall,floor,ceilingsandroofjunctions.
Figure16showsgenerallylocationswheretimberblockscanbeused.Itisimportantthattheextra
timberblockshouldnotalsohaveastructuralproposeunlessshownotherwise.Iftheelementis
requiredtosupportloadthenthesetimberblocksareinadditiontotimberworkrequiredforstructural
adequacy.

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