01
Timber-framed Construction
for Townhouse Buildings
Class 1a
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

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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.
Topics include:
#01 Timber-framed Construction for
Townhouse Buildings Class 1a
#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


WoodSolutionsisanindustryinitiativedesignedtoprovide
independent,non-proprietaryinformationabouttimberand
woodproductstoprofessionalsandcompaniesinvolvedin
buildingdesignandconstruction.
WoodSolutionsisresourcedbyForestandWoodProducts
Australia(FWPA).ItisacollaborativeeffortbetweenFWPA
membersandlevypayers,supportedbyindustrypeak
bodiesandtechnicalassociations.
ThisworkissupportedbyfundingprovidedtoFWPA
bytheCommonwealthGovernment.
ISBN978-1-920883-78-2
Researcher:
TimberDevelopmentAssociation(NSW)
Suite604,486PacificHighway
StLeonardsNSW2065
Printed:May2010
Revised:May2012
© 2012 Forest and Wood Products Australia Limited.
All rights reserved.
ThesematerialsarepublishedunderthebrandWoodSolutionsbyFWPA.
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Table of Contents


Introduction

4


Step1–High-LevelBCADesignIssues

6

1.1 DeterminetheClassofBuilding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.2 BCACompliance–DeemedtoSatisfyProvisionsorAlternativeSolutions . . . . . . . . . . . . 6
1.3 FireandSoundSeparationinBuildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Step2–DefineBCASound-DesignRequirements

9

2.1 UtilisingtheDeemedtoSatisfyProvisionsforSoundDesign. . . . . . . . . . . . . . . . . . . 9
2.2 DetermineSound-InsulationRequirementsInSeparatingWalls . . . . . . . . . . . . . . . . .10
2.3 TreatmentofServicesRelevanttoTimber-FramedConstruction . . . . . . . . . . . . . . . . .11
2.4 TheNextStep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Step3–ImproveandUpgradeSoundPerformance

12

3.1 CheckingandAdjustingtheBuildingDesigntoReduceSoundTransmission . . . . . . . . . .12
3.2 StrategiesforImprovingSoundPerformanceinConstruction. . . . . . . . . . . . . . . . . . .13
3.3 TheNextStep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Step4–DefineFire-DesignRequirements

16

4.1 UtilisingtheDeemedtoSatisfyProvisionsforFireDesign . . . . . . . . . . . . . . . . . . . .16
4.2 FireResistanceLevelsofWallElements . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
4.3 TheNextStep . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Step5–SelectSound-andFire-RatedTimberConstructionSystems


19

5.1 PrinciplesforAchievingFireResistanceLevelsinTimber-FramedConstruction . . . . . . . . .19
5.2 PrinciplesforAchievingSoundInsulationinTimber-FramedConstruction . . . . . . . . . . . .21
5.3 Sound-andFire-RatedWallConstructionSystems . . . . . . . . . . . . . . . . . . . . . . . .21
5.4 Solid-TimberConstructionJoints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
5.5 TreatmentofRoofVoids. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
5.6 SeparationWallAbuttingExternalWalls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
5.7 SteelColumnsinSeparatingWalls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
5.8 ServicePenetrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Step6–FurtherDesignAssistance(Appendices)

37

AppendixA–ResolvingStructuralDesignConsiderationsandConstructionPractices . . . . . . . .37
AppendixB–DesignReferences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
AppendixC–Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

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

Page 3


Introduction

This Guide covers
fire and sound.

Fireandsoundareimportantissuesinresidentialconstruction.Soundinsulationtends

togovernthechoiceofconstructionsystembecauseofitsdailyimpactonthebuilding
occupants’qualityoflife,whilefire-resistingconstructionisimportantforprotectingagainst
extremeevents.
ThisGuideaimstoassistinbothareasandisspecificallywrittenforusebydesigners,
specifiers,buildersandcertifyingauthorities.Itisset-outaccordingtoasimplestep-by-step
processshowninTable1.Thestepsarethenusedasthebasisforheadingsthroughout
therestofthedocument.DetailsonthescopeandotherimportantaspectsoftheGuideare
detailedbelow.
Scope
Fortimber-framedconstruction,thisGuidedemonstratescompliancewithtargetedfiresafetyand
sound-insulationPerformanceRequirementsintheBuildingCodeofAustraliaforClass1aattached
buildingsandassociatedClass10abuildings.Specificareasofperformanceaddressedinclude:
• Providingsoundinsulationinwallsbetweendwellings.
• Protectionagainstspreadoffirebothbetweendwellingsandonexternalwalls(whererequired).
Itdoesnotdealwithfiredetectionandearlywarninginbuildings(includingsmokealarms),heating
applianceissues,bushfiresorfireinalpineareas.
ThisGuideprovidescertifiedconstructiondetailsbyutilisingtheBCA’sDeemedtoSatisfyProvisions.
Inaddition,guidancebeyondBCAminimumrequirementsisprovidedforthosewantingtoimprove
andupgradesoundperformance.

Although national,
some BCA provisions
differ by state.
It’s vital to know
key variations for
your area.

Regulatory Differences Between States of Australia
ThispublicationfocusesoncurrentBCArequirements.FromtimetotimeState-basedBCA
amendmentsmayvaryrequirements.UsersofthisGuideshouldmakethemselvesawareofthese

differencesandshoulddevelopafullunderstandingoftheresultingimplications.Onlyonthisbasis
shouldthisGuidebeused.

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

Page 4


Table 1: Design process for sound- and fire-resistant timber-framed construction
Step1–High-LevelBCADesignIssues
Taking a step-by-step
approach reduces
complex designs
to manageable
elements.

DeterminetheClassofbuilding
DeterminethebasisforcomplyingwithBCAPerformance
Requirementsi.e.DeemedtoSatisfyProvisionstobeused

Determinethesetoutofseparatingwallsbetweendwellings

Step2–DefineBCASoundDesignRequirements
UtilisetheDeemedtoSatisfyProvisionsforsounddesign
Determinesound-insulationrequirementsforseparating

Step3–ImproveandUpgradeSoundPerformance
Attentiontobuildingdesign(spaceand
Addressflankingnoise
Strategiesforimprovingsoundperformance


Step4–DefineBCAFire-DesignRequirements
UtilisetheDeemedtoSatisfyProvisionsforfiredesign
DeterminetheFireResistanceLevelsofwall

Step5–Sound-andFire-RatedTimberConstruction
Taking a step-by-step
approach reduces
complex designs
to manageable
elements.

Principlesinfire/sound-ratedtimberconstruction
Selectafire/sound-atedtimber-framedsystem
Detailtheselectedsystem,e.g.joints,

Step6–FurtherDesignAssistance(Appendices)
Structuralconsiderations,otherBCArequirements,references,

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

Page 5


1
This Guide covers
BCA Class 1a and
10a buildings. It’s
also relevant to
Class 1b structures.


Step 1 – High-Level
BCA Design Issues
TheBCAistheregulatoryframeworkfordeterminingminimumconstructionrequirements
foralltypesofbuildingsinAustralia.Itcontainsdifferentlevelsofdetailthatsubsequently
causedifferentlevelsofdecisionmakingtobemadeonabuildingproject.Aselectionof
high-leveldesignissuesrelatingtofire-resistingandsound-insulationconstructionare
addressedinthissectionoftheGuide.
1.1 Determine the Class of Building
TheBuildingCodeofAustralia(BCA)containsmandatoryPerformanceRequirementswhichapplyto
10primaryclassesofbuilding.Theseclassesaredeterminedaccordingtothepurposeforwhicha
givenbuildingwillbeused.TheclassesrelevanttothisGuideare:
• Class1aattacheddwellingseachbeingabuildingseparatedbyafire-resistingwallincludingrow
houses,terracehouses,townhousesorvillaunits.
• Class10anon-habitablebuildingsthatareattachedorinsomewayassociatedwiththeabove
Class1abuildingsincludingprivategarages,carportsandsheds.
TheseclassesaredealtwithinVolume2oftheBCAandsoallfuturereferencestotheBCAaremade
withrelevancetothisVolume.OtherClass1buildingsnotspecificallydealtwithinthisGuide,but
whichmaystillbenefitfromspecificinformationcontainedwithin,include:
• Class1adetacheddwellings.
• Class1bboardinghouses,guesthouses,hostelsandsimilarbuildings(Note:Class1bbuildings
aredefinedashavingatotalfloorareaupto300m2andwouldnotordinarilyhavemorethan12
peopleasresidents).
• BoththesetypesofbuildinghavenospecificsoundPerformanceRequirementsintheBCAand
onlyrequirefire-resistingconstructionwhereexteriorwallshavecloseproximitytoanallotment
boundaryorcloseproximitytoanadjacentbuilding(referBCA3.7.1.3).
CareisrequiredtoensurethatClass1abuildingsdonotinadvertentlyhavetheirbuildingclassification
changed.Commoncausesofthisare:
• Twoormoredwellingssharingacommongarage.
• Twoormoredwellingsharingacommonentrance.

• Onedwellingconstructionoverlappingontoanotherbelow.
1.2 BCA Compliance – Deemed to Satisfy Provisions or Alternative Solutions

Refer BCA 1.0.9 and
1.2.2 to 1.2.4.

BCAPerformanceRequirementscanbeachievedfortheabovebuildingclassesintwodifferentways:
• DeemedtoSatisfyProvisions–aspecifictypeofconstructionwhichisacknowledgedascomplying
withtheBCA’sPerformanceRequirements.ThisincludesAcceptableConstructionPracticesforfire
andsound,asdetailedinVolume2oftheBCA.
• AlternativeSolutions–thismeansasolutionnotdealtwithunderDeemedtoSatisfyProvisions
andmustbeproventosatisfyBCAPerformanceRequirements.Suitableassessmentmethodsare
identifiedintheBCA.
TheconstructionsystemsanddetailsinthisGuidecomplywiththeDeemedtoSatisfyProvisionsby
utilisingtheAcceptableConstructionPracticesinVolume2.ThispartoftheBCAdirectsthelevelof
fire-resistingandsound-insulationconstructionthattimber-framedconstructionmustachieveinorder
tomeetminimumBCAPerformanceRequirements.ApprovedBCAmethodsofassessmentarethen
usedtoensurethatthetimber-framedconstructionsystemsshowninthisGuidecomplywiththe
levelsrequired.

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

Page 6


1.3 Fire and Sound Separation in Buildings
Inordertopreventthespreadoffireandprovidesoundinsulationbetweenbuildings,therearekey
conceptsusedintheBCA’sAcceptableConstructionPracticesincluding:
SeparatingWalls–SuchwallsseparatetheeffectsoffireandsoundonadjoiningClass1abuildings
byvirtueofacommonwall.Thewallcommencesatthelowestfloorlevel(orpossiblygroundlevel

wherearaisedfloorisinvolved)andfinishesateithertheundersideoftheroofingmaterialorinsome
instancesasetdistanceabovetheroofline(Figures1and2).Morespecificconditionsconcerning
separatingwallsarediscussedlaterinthisGuide.
ExternalWalls–Suchwallsareimportantinprotectingabuildingagainstspreadoffirefromexternal
firesources(Figures1and2).Thesewallsaredeemedtooccurwhere:
• 900mmorlessfromanallotmentboundaryotherthantheboundaryadjoiningaroadalignmentor
otherpublicspace;or
• 1.8morlessfromanotherbuildingonthesameallotmentotherthanaClass10buildingora
detachedpartofthesameClass1building.
MorespecificconditionsconcerningexternalwallsarediscussedlaterinthisGuide.

required to be fire rated
because they are greater
than 900 mm from boundary
and greater than 1800 mm
from other buildings
measured at right angles

Boundary
These walls not required
to be fire rated because
they are greater than 900
mm from boundary and
greater than 1800 mm
from other buildings
measured at right angles

1800 mm

The portion of the

wall within 900 mm
of boundary to be
FRL 60/60/60

900
mm

Dwelling 3

Dwelling 1

ry

Dwelling 2

da

un

Bo

900
mm

Dwelling 4
900
mm

Walls within 1800 mm of
another building

measured at right angles
to be FRL 60/60/60

This wall not required to be
fire rated because it is greater
than 900 mm from boundary
and greater than 1800 mm
from other buildings
measured at right angles

Boundary

Walls within 900 mm of
boundary measured at right
angles to be FRL 60/60/60
Boundary

Two clear BCA
conditions make it
straightforward to
deem external walls.

Boundary

Figure 1: Examples of a separating walls and external walls – plan view.

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

Page 7



Separating wall above
combustible roof coverings

Dwelling 3
Dwelling 1

Dwelling 4

Dwelling 2

External walls to be fire rated if
within 900 mm of boundary or
1800 mm of another building

Separating wall continued up
to underside of non-combustible roof
Fire-rated external wall
above lower roof

Dwelling 8
Dwelling 5

Dwelling 6

Dwelling 9

Dwelling 7

Suspended floor


Separating wall continued
down to ground

Fire-rated external wall continued
up to underside of combustible roof
or non-combustible eaves lining

Dwelling 10

Separating wall continues
from ground to underside of
non-combustible roof covering

Dwelling 11

Dwelling 12

Private garages may be under
or within Class 1a dwelling

Dwelling 13

Attached carports or
garages (Class 10a)

Figure 2: Examples of a separating walls and external walls – elevation view.

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


Page 8


2
Addressing multiple
sound sources is
even more important
in light of today’s
trend towards
medium density
housing.

Step 2 – Define BCA SoundDesign Requirements
Designingsound-insulatedconstructioninvolvesaprocessofunderstandinghowtheBCA’s
PerformanceRequirementstranslateintoobjectivedesignparameters,ascontainedinthe
BCA’sDeemedtoSatisfyProvisions(i.e.acceptableconstructionpractice).Thisisthenused
asthebasisforselectingappropriatetimber-framedconstruction.Keyissuesdetermining
sounddesignrequirementsarediscussedinthisSectionoftheGuide.
2.1 Utilising the Deemed to Satisfy Provisions for Sound Design
TheBCA’sPerformanceRequirementsforsoundinsulationconcerntheuseofseparatingwalls
betweendwellingstosufficientlyinsulateagainstairbornesoundtransmissionandimpactnoise.In
ordertounderstandtheserequirementsitisimportanttodifferentiatebetweenairborneandimpact
soundasshowninFigure3.

Airborne sound

Impact sound

Figure 3: Examples of impact and airborne sound.


2.1.1 Airborne Sound Transmission
Airbornesoundtransmissionreferstosoundwavesthattravelthroughtheairandcauseabuilding
elementtovibrate,radiatingoutontheothersideofthewall.Methodsusedtoreducetransmitted
airbornesoundgenerallyusecavity(isolated)constructionwithbulkinsulationstoabsorbthe
vibration.
DeemedtoSatisfyconstructionthatmeetstheabovePerformanceRequirementsisprovidedinthe
AcceptableConstructionPracticespartoftheBCA(BCA3.8.6).
2.1.2 Impact Sound Transmission
Impactsoundreferstothesoundarisingfromtheimpactofanobjectonabuildingelementcausing
bothsidesofthebuildingelementtovibrateandgeneratessoundwaves.Theprimarymethodusedto
reduceimpactnoiseisisolationfromanyadjoiningbuildingelements.
Generally,theBCAconsidersimpactsoundforwallsseparatingabathroom,sanitarycompartment,
laundryorkitcheninonedwellingfromahabitableroom(otherthanakitchen)inanadjoining
dwelling.Soundleakageatpenetrationsfromserviceelementsmaycompromisetheperformanceof
#01 • Timber-framed Construction for Townhouse Buildings Class 1a

Page 9


walls.Thisrequirementisgenerallyachievedwithdiscontinuousconstruction.RefertoAppendixCfor
adefinitionofdiscontinuousconstruction.
Itisalsoimportanttounderstandhoweachtypeofsoundismeasuredinordertoselectsoundinsulatedseparatingwalls.ThenomenclatureusedintheBCA’sAcceptableConstructionPracticeis
explainedinFigure4.
Proper sound
insulation isn’t
‘bolted on’. It starts
at the bottom and
permeates every
level of construction.


AirbornesoundismeasuredusingtheWeightedSoundReduction
IndexwhichisexpressedasRw(e.g.50Rw)
•Thehigherthenumberthebettertheperformance
•ItcanbeusedonitsownormodifiedusingaCtrfactor(seebelow)
ACtr.modificationfactorcanbeaddedtotheRwmeasurementtobiasthe
overallmeasurementtotakegreateraccountoflowfrequencybassnoise.
CtrisusuallyanegativenumberandsoeventhoughitisaddedtotheRw
value,thenetresultisalowernumberthantheRwvalueonitsown.Itis
thereforesignificantlyhardertoachieve50Rw+Ctrthan50Rwonitsown

Applyingtheabove,involvesfindingoutthe
minimumstatedRworRw+Ctrforaseparatingwall,
thenselectingtimber-framedconstructionthatsuits.
Figure 4: Methods of measuring airborne sound.

2.2 Determine Sound-Insulation Requirements In Separating Walls
Giventhepreviousdefinitions,therequiredairborneandimpactsoundinsulationlevels,asinterpreted
fromtheBCAforClass1abuildings,areprovidedinTable2.Inadditiontotheserequirements,there
aregeneralinstallationrequirementsintheBCA(referBCA3.8.6.3).Akeyissuehereisthattoachieve
therequiredsoundlevels,wallsmustbesealedatjunctionsbetweenthesound-insulatedseparating
wallandanyperimeterwallsorroofcovering.Inaddition,timberstudsandperimetermembersmust
beinstalledasfollows:
• Studsmustbefixedtotopandbottomplatesofsufficientdepthtopermitsecurefixingofthe
plasterboard.
• Noggingsandlikemembersmustnotbridgebetweenstudssupportingdifferentwallleaves.
• Alltimbermembersattheperimeterofthewallmustbesecurelyfixedtotheadjoiningstructure
andbeddedinresilientcompoundorthejointsmustbecaulkedsotherearenovoidsbetweenthe
timbermembersandthewall,refertoliningmanufacturer’sinstallationrecommendations.
Note:BCArequirementsfortimber-compatiblematerialsuchasplasterboardshouldbeviewed
separatelyintheBCA(referBCA3.8.6.3)and/orproprietaryinstallationmanuals.

Table 2: Minimum sound insulation requirements for separating walls.
Discontinuous
Construction
Required

Rw+Ctr

Betweenabathroom,sanitarycompartment,laundryorkitchen
andahabitableroom(otherthanakitchen)inanadjoining
Class1building

YES

50

Inallothercases,includesroofvoidandsubfloorareas

NO

50

• iftheadjacentroomishabitable(otherthankitchen)

NO

40

• iftheroomisakitchenoranyotherroom.

NO


25

SEPARATINGWALL–
LocationandPenetrations

Duct,soil,wasteandwatersupplypipesandstormwaterpipes
thatpassthroughaseparatingwallbetweenClass1buildings:

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

Page 10


2.3 Treatment of Services Relevant to Timber-Framed Construction
Ifaduct,soil,waste,watersupplyorstormwaterpipeservesorpassesthroughaseparatingwalloris
locatedinaseparatingwall,thenthefollowingconditionsapply:
• Adoororpanelprovidingaccesstoaductorpiperequiredtobeseparatedmustnotopenintoany
habitableroomotherthanakitchen.Inanyotherpart,thedoororpanelmustbefirmlyfixedsoasto
overlaptheframeorrebateoftheframebynotlessthan10mmandbeconstructedof:
–wood,plasterboardorblockboardnotlessthan33mmthick;or
–compressedfibre-cementsheetingnotlessthan9mmthick;or
–othersuitablematerialwithamassperunitareanotlessthan24.4kg/m2.
• Ifitisawatersupplypipe,itmust:
–onlybeinstalledindiscontinuousconstruction(doublestudwalls);and
–inthecaseofawatersupplypipethatservesonedwelling,notbefixedtothewallleafonthe
sideofanyotherdwellingandhaveaclearancenotlessthan10mmtotheotherwallleaf.
Electricaloutletsmustbeoffsetfromeachotherintimberframingnotlessthan300mm.
2.4 The Next Step
Havingusedthepreviousinformationtoobtainastrongunderstandingoftheminimumsound

insulationrequirementsforseparatingwalls,thenextstepistoeither:
• GotoStep3toimproveand/orupgradesoundperformance,or
• GotoStep4findoutabouttheBCAfire-resistingconstructionrequirements.

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

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3

Step 3 – Improve and Upgrade
Sound Performance
Soundperformancecanoftenbeimprovedbysimpleattentiontotheformandspatial
arrangementofthebuildingdesign.Inaddition,manyendusersofdwellingsoftenwant
highersoundperformancethantheminimumlevelsrequiredintheBCA.Asaresult,this
StepoftheGuidefocusesonwaysofimprovingandupgradingsoundperformance.
3.1 Checking and Adjusting the Building Design to Reduce Sound Transmission

Quiet dwellings
command premium
prices, so it may pay
to exceed minimum
sound performance
standards.

TherearemanyaspectsofClass1abuildingsthatcanreducesoundtransmissionbysimplypaying
attentiontothoughtfulsounddesign(Figure5).
3.1.1 Room Layout
Checkthattheroomlayoutisbeneficialratherthandetrimentaltosoundtransmission.Servicerooms

includingbathrooms,laundriesandkitchenscreateextrasoundcomparedtolivingroomsand
bedrooms.Forinstance,watermovementthroughplumbingpipesandthevibrationfromwashing
machinesanddishwasherscreatesoundproblems.Itisthereforebestfortheserviceroomsinone
dwellingtobackontothesameroomsinanadjoiningdwellingandshouldnotbackontohabitable
rooms.Also,trytoensureentrancestodwellingsareanappropriatedistancefromattachedor
adjacentdwellings.
3.1.2 Windows

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

Windowsnormallyhavelowersoundinsulationthanthewallstheyarelocatedwithin.Asaresult,high
soundratedwallsystemsmaybecomeineffectivebyvirtueofpoorlysound-insulatedwindows.Where
noiseisunavoidable,consideroneormoreofthefollowing:
• Usethickerglassordoubleglazing.
• Usefixedglazinginlieuofopeningwindows.(Thismayalsorequiresound-insulatedventilation.)
• Locatewindowssothattheydonotfacenoisyareas.
• Provideadequateseparationbetweenwindowsinadjoiningdwellings.
• Reducetheareaofwindowsinthefacade.
• Fillvoidsbetweenthewallframeandwindowframewithanappropriateacousticsealant.
• Useacousticsealingstrips/gasketsaroundtheedgesoftheopenablesashesandthewindow
frame.
3.1.3 Doors
Aswithwindows,doorstendtobetheweaklinkinsoundratedwalls.Wheresound-controlisdesired,
solidcoredoorsshouldbeused.Thetopandsidesofdoorsshouldhavesoftacousticgaskets.
Thresholdclosersatthebottomofthedoororairsealswillalsoreducesoundtransmission.Sliding
doorsshouldbeavoidedwhereoptimumsound-controlisdesired.

3.1.4 Services
Thelocationanddetailingofservicesaretwoofthemostimportantconsiderationsincontrolling
soundtransmissioninresidentialbuildings.
Generally,servicesandservicepenetrationsshouldnotbelocatedonseparatingwallsbutratheron
internalwallsordedicatedsoundresistantserviceshafts.Inallinstances,servicepipesshouldbe
locatedawayfromnoisesensitivepartsofthedwellingsuchasbedrooms.

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

Page 12


Services and service
ducts positioned away
from separating wall

Bathroom

Bathroom

Similar rooms adjoin

Dwelling 1

Combined sound
insulation strategies
generally yield better
results than standalone measures.

Dwelling 2


Living

Living

Garage

Dining

Garage

Dining

Kitchen

Kitchen

Similar rooms adjoin
Ground Floor

Bathroom

Points of entry for people and vehicles spaced further apart

Bathroom and
staircase separated
from the bedrooms

Bathroom
Similar rooms adjoin


Bedroom

Bedroom

Bedroom

Bedroom

Level 1
Bedrooms located away from public areas

Figure 5: Sound design practices in building layout.

3.1.5 Flanking Noise
Flankingnoiseisbestaddressedby:
• isolatingofformingdiscontinuouselementsfromeachother,i.e.resilientacoustictiesand
discontinuousflooring,and
• placingabsorptivematerialwithinsoundratedcavities,ornearfloor/ceilingandwalljunctions.
3.2 Strategies for Improving Sound Performance in Construction
Thefollowingstrategiescanbeusedtoimprovethesoundinsulation.Generally,itisnottheuseof
onebutacombinationofstrategiesthatgivesthemosteconomicalsolution.
Extramassonthewall–theadditionofmassisasimpleyetimportantmeansofimprovingsound
performanceintimber-framedconstruction.Atitssimplest,thisinvolvesaddingextralayersofmaterial
suchasplasterboardorfibre-cementsheettotheseparatingwallsystem.
Useawiderwall(90mmwallstuds)–Thewiderthewall,thebetteritssoundperformance.Thisis
particularlythecasewhentryingtoimproveCrtscores(beingthemodificationfactorforlowfrequency
bassnoiseappliedtoRwscores).Thesimplestwaytodothisistouse90mmwidestudsinsteadof,
say,70mmwidestudsinadoublestudwallsystem.
Upgradebattsinthewall–Therearemanydifferenttypesandgradesofinsulationbattsavailable.

Sound-insulationspecificbattsarebest,andinaddition,higherdensitymaterialstendtooutperform
lowdensitymaterialsbutasaminimum,battswithdensitiesof10kg/m3orgreaterarerecommended.
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Floorjoistsparalleltoseparatingwalls–Byrunningfloorjoistsparallelratherthantransverseto
theseparatingwall,lessimpactsoundfromthefloorwillgointotheseparatingwallandsubsequently
lessimpactsoundwilltransferacrossthewalltotheattachedbuilding(Figure6).

Structural blocking
(as required) to
support upper walls

Flooring not
continuous under
wall plate

Timber
blocking to
support
flooring

Flexible fire-grade
sealant

Timber packers

Flexible fire-grade

sealant

Floor joists parallel
to separating wall

Sacrificial solid timber
blocking for fire
resistance

Fire- and
sound-rated linings

Batts do much more
than save energy.

Figure 6: Joists parallel to separating wall – elevation view.

Battsintheflooratthewall/floorjunction–Wheretheparalleljoistlayout(Figure6)cannotbe
achieved,itisgoodpracticetoplaceextrasound-insulationbattsbetweenjoistsrunningalongthe
separatingwall(Figure7).Muchthesamecanbedoneatwallandceilingintersections,butisonly
requiredwheresuchinsulationisnotalreadyprovidedacrosstheentireceilingarea,suchasfor
energyefficiency.

Timber packers
Structural blocking
(as required) to
support upper walls

Floor joists
parallel to

wall

Flooring not
continuous under
wall plate

Timber blocking to
support flooring

Acoustic
insulation

Blocking to fix
plasterboard
were required
Flexible fire-grade
sealant

Flexible fire-grade
sealant
NOTE: Flooring may
require continuous
supported at perimeter

Floor joists
perpendicular
to wall

Joist
hanger


Acoustic
insulation

Sacrificial solid-timber
blocking for fire
resistance
Fire- and
sound-rated linings

Figure 7: Sound insulation batts at floor and wall intersection – elevation view.

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Isolatedsupportforstairs–Impactsoundfromstairusagetypicallyvibratesitswayintoseparating
walls,creatingagreaterlikelihoodofsoundpassingacrossthewallintoattacheddwellings.Thebest
waytopreventthisisbyisolatingthesupportforthestairstructure(Figure8).Optionsinclude:
• usingthestringerstosupportthestairs,ateachfloorlevel,withoutintermediatesupportfromthe
separatingwallinbetween,i.e.freestanding
• usingNewellpostsratherthantheseparatingwalltosupportthestairstructure.
Fire- and
sound-rated linings
20mm recommended
separating gap
Timber treads

Timber stringer


Note: Isolating stairs from
wall provides superior
sound performance

Figure 8: Isolating stair structure from separating wall – elevation view.

Battenoutseparatingwallsinwetarea–Inwetareaconstruction,fire/soundratedwallscanbe
compromisedwherebathandshowerbaseunitsneedtoberecessedintothewall.Asimplemeans
ofdealingwiththisistobattenouttheseparatingwall(afterfireessentialliningshavebeenapplied)
andthenprovidinganadditionalliningoverthetop(Figure9).Thebathcanthenbeinstalledintothe
battenspacewithoutaffectingthefire-andsound-ratedwall.

Lining board suitable
for wet areas

Fire- and
sound-rated linings

Void created by battens
can be used for services

Timber batten (35 mm
minimum thickness)

Timber support
batten fixed to studs

Edge of bath/shower
not to be recessed into

fire-rated wall

Note: waterproofing
membrane not shown

Bath tub

Figure 9: Batten out false wall for services – elevation view.

3.3 The Next Step
ThestrategiesandmethodsshowninthisStepoftheGuidemayinvolvespecialistproprietary
systemsthatgobeyondthescopeofthispublication.Asaresult,thenextstepistoeither:
• gotoproprietarysystemsuppliersandaskforadviceonhowtointegratetheirsystemswiththose
discussedinthisGuide,or
• gotoStep4tofindoutaboutBCAfire-resistingconstructionrequirements.

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4

Step 4 – Define Fire-Design
Requirements
Likesound,designingfire-resistingconstructioninvolvesaprocessofunderstanding
howtheBCA’sPerformanceRequirementstranslateintoobjectivedesignparameters,
ascontainedintheBCA’sDeemedtoSatisfyProvisions(i.e.acceptableconstruction
practices).Thisisthenusedasthebasisforselectingappropriatetimber-framed
construction.KeyissuesarediscussedinthissectionoftheGuide.

4.1 Utilising the Deemed to Satisfy Provisions for Fire Design

Refer BCA 3.7.1

Recent bushfire
seasons have made
fire resistance a hot
issue even for urban
building projects.

Asdiscussedpreviously,thisGuidefocusesonmeetingPerformanceRequirementsconcerning
protectionagainstthespreadoffirebetweenClass1abuildings(adjacenttoeachother)and
associatedClass10abuildings.AcceptableconstructionpracticesthatareDeemedtoSatisfythese
requirementsandofrelevancetotimber-framedconstruction,aresetoutinPart3.7.1oftheBCA.It
providesFireResistanceLevelsandassociatedconstructiondetailsforexternalwallsandseparating
walls.FireResistanceLevelsrepresentakeyrequirementwhenselectingappropriatetimber-framed
constructionsystemsforfireseparationandthereforeformthebasisforongoingdiscussion.
AFireResistanceLevel(FRL)expressestheminimumamountoftime(inminutes)thatabuilding
elementmustresistafireasdefinedbythreeseparatecomponents:
• Structuraladequacy(abilitytowithstandloads);
• Integrity(intermsofcontainingsmoke,flamesandgases);and
• Insulation(intermsoflimitingthetemperatureononesideoftheelementgettingthroughtothe
otherside).
AnexampleofthewaythatanFRLisexpressedis:60/60/60.Anotherexamplewherenotall
componentsarerequiredis:–/60/–.Applicationofthisandrelatedaspectsofconstructionare
discussedunderthefollowingheadings.
4.2 Fire Resistance Levels of Wall Elements
4.2.1 External Walls
ExternalwallsareusedtoprotectClass1abuildingsfromexternalfiresources(Figures1and2).
Specificrequirementspertainingtothisinclude:

• MusthavewallswithanFRLofnotlessthan60/60/60whentestedfromtheoutside.
• Musthavewallsthatextendtotheundersideofanon-combustibleroofcoveringor
non-combustibleeaveslining.
• Musthaveopeningsinwalls:
–protectedbynon-openablefirewindoworotherconstructionwithanFRLofnotlessthan–/60/–
–protectedbyself-closingsolidcoredoorsnotlessthan35mmthick.
AdditionalNotes:

Refer BCA 3.7.1.7

Certainconstructionisallowedtoencroachonthe900mmspacebetweenanexternalwalland
theallotmentboundaryor1800mmspacebetweentheexternalwallsoftwobuildingsonthesame
allotment(referBCA3.7.1.7fordetails).ConditionsapplyasdefinedinBCA3.7.1.7butofrelevanceto
timber-framedconstructionistheallowableencroachmentofnon-combustibleeavesconstruction.
Certainconcessionsexistforwindowsinnon-habitablerooms.Windowsthatfacetheboundaryof
anadjoiningallotmentmaybeusedifnotlessthan600mmfromthatboundaryor,windowsthat
faceanotherbuildingonthesameallotmentmaybeusedifnotlessthan1200mmfromthebuilding.
Conditionsconcerningthemeasurementofdistances,theopenableareaofwindowsandother
featuresaredetailedinBCA3.7.14and3.7.1.5d.
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Sub-floorvents,roofvents,weepholes,controljoints,constructionjointsandpenetrationsforpipes,
conduitsarenotconsideredasopenings,referBCA3.7.1.2(c).
4.2.2 External Walls where Class 10A Buildings are Involved

Refer BCA 3.7.1.6.


TheissueofexternalwallsbecomesmorecomplicatedwhereClass10abuildings(suchasgarages)
haveaninterveninginfluencebetweenthefiresourceandtheClass1abuilding(referBCA3.7.1.6
forillustrationofthis).Thispotentiallycausesaredesignationof(fire-resisting)externalwalllocation.
Situationsaffectedincludewhere:
• aClass10abuildingoccursbetweenaClass1abuildingandtheallotmentboundary;

Garages and other
Class 10a buildings
can affect wall
designation. The
BCA shows the way.

• aClass10abuildingoccursbetweenaClass1abuildingandotherbuildingsonanallotment;and
• Class10abuildingsmustbeseparatedonanallotmentbecauseoframificationsonattachedor
adjacentClass1abuildings.
TheBCAgivesquiteadetaileddescriptionofthemanyoptionsavailableandreferencetothisis
recommended.
4.2.3 Separating Walls
Separatingwallsareusedtoprovidefire-resistanceandsoundinsulationbetweenattachedClass1a
buildings(Figures1and2).Specificrequirementspertainingtothisinclude:
• MusthavewallswithanFireResistanceLevelofnotlessthan60/60/60.
• Mustcommenceatthefootingsorgroundslabandextendupaccordingtooneofthefollowing
scenarios:






–Foranon-combustibleroofcoveringthewallmustextendtotheundersideoftheroof


(Figure2).Thewallmustnotbecrossedbytimbermembers(orothercombustiblebuilding
elements)otherthanroofbattens(maximum75x50mm)orsarking.Voidsbetweenthetop
ofwallandundersideofroofing(i.e.betweenbattens)mustbefilledwithsolidtimber75mm
thick(min),mineralwoolorothersuitablefire-resistingmaterial.



–Foracombustibleroofthewallmustextend450mmabovetheroofasshowninFigure2.

• Mustaddresspotentialspreadoffirethatcanpotentiallyoccurwheretheendofaseparatingwall
intersectswithamasonryveneerwallandthecavityofthelatterwallsactsaspassageforfire.
Here,thecavitymustbenogreaterthan50mmwideandpackedatthewallintersectionwithfireresistantmineralwoolorothersuitablefire-resistingmaterial.Thepackingmustbedetailedtomeet
weatherproofingrequirementsandfurtherdetailsaregiveninStep5ofthisGuide.
• Eaves,verandahsandsimilarspacesthatareopentotheroofspaceandarecommontomorethan
oneClass1adwellingmustbeseparatedbyanon-combustibleverticallining.
• Forelectricalcables,wires,switches,outlets,socketsorthelikepenetratingaseparatingwall,the
wallatthepenetrationmustachieveanFireResistanceLevelof60/60/60andmustbetestedin
accordancewithAS4072.1andAS1530.4.
• Otherconditionsalsoapplyincludingthespacingbetweencertainpenetrations;theaccuracyof
installation;thetreatmentofresidualgapsbetweenthewallandelectricalfitments/cables;the
treatmentofcavityspacesbehindelectricalfitmentswithfire-resistingmaterials.Theseaspectsare
addressedinStep5ofthisGuide.
4.2.4 Combined External and Separating Wall
InthesituationwhereadjoiningClass1abuildingsaresteppedinheight,therecomesasituation
wherethereisconfusionoverwhichpartofthewallisaseparationwallandwhichisanexternalwall
(Figure10).InthesecircumstancestheBCAissilentanditisrecommendedthatthewallabovethe
lowerrooflineistreatedasafire-ratedexternalwall.

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Separating wall continued up
to underside of non-combustible roof
Fire-rated external wall
above lower roof

Dwelling 5

Dwelling 6

Figure 10: Stepped roof line in Class 1a buildings.

4.3 The Next Step
Havingusedthepreviousinformationtoobtainastrongunderstandingoffire-resistingconstruction
requirementsintheBCA,gotoStep5toselectcomplyingtimber-framedconstruction.

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5

Step 5 – Select Sound- and
Fire-Rated Timber Construction
Systems
ThisStepfocusesonmatchingthepreviouslydiscussedAcceptableConstruction

Practicesforbothsound(e.g.RW+Ctr,)andfire(e.g.FRLs)withappropriatetimberframedconstruction.ThisStepbeginsbyexplainingkeyprinciplesusedintimber-framed
constructiontoaddresssoundandfireneeds.Theseprinciplesarethenpresentedinthe
formofintegratedsystemse.g.timber-framedwall,floorandceilingsystems.Importantly,
constructiondetailsareprovidedforeachsystemintermsoffire/soundratedjunctions
betweenelements,penetrationsinelements,stairconstructiondetails,treatmentofservices
andsimilarsituations.
5.1 Principles for Achieving Fire Resistance Levels in Timber-Framed Construction
5.1.1 Fire-Grade Linings Provide the Primary Source of Protection to
Fire-Rated Timber-Framed Walls
Thegreaterthenumberoflayers,thegreatertheresistancetofire.Thisisevidentwhenviewing
themainfire-resistanttimberframingsystemsdescribedandshowninSection5.2.Additional
measures,asdetailedbelow,arerequiredatweakspotsorbreaksinthefire-gradeliningsthatoccur
atintersectionsbetweenwall,floorandceilingelements.Cornerlapsandexposededgesinlining
sheetspresentanotherareaofconcern.Extraattentionisalsoneededatpenetrations,openingsand
protrusions.
5.1.2 Construction Joints
Inrelationshiptofire-resistanceonlyConstructionJointsarefire-gradematerialsusedtoclosegaps
intheconstructionthatoccurbetweenfire-gradematerialsandatservicepenetrations.Theyrestrict
heat,smokeandgasesfrommovingbeyondacertainpointintheconstruction.Therearevarious
situationswheresuchgapsoccurandsovariousoptionscanbeusedtoactasfirestopmaterials,
including:
• fire-resistingmineralwoolasshowninFigure11
• fire-resistingsealantasshowninFigure12.

More layers =
better fire resistance.
Laps, edges,
penetrations,
openings and
protrusions have the

opposite effect.

Fire- and
sound-rated linings

Timber studs to
support wall linings

Additional 45 mm solid
timber blocking

Fire-resistant mineral
wool with vertical DCP

Flexible fire-grade
sealant

Figure 11: Fire-resisting mineral wool – plan view.

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Flexible fire-grade
sealant used to
seal between
plasterboard and
pipe penetrations


Mineral
wool
around
pipe

Fire- and
sound-rated linings

Figure 12: Fire-resistant sealant – elevation view.

By forming a char
layer when it burns,
solid timer can
achieve the fire
resistance of firegrade linings.

Solidtimbercanbeusedasconstructionjointsastheycanachievetheequivalentfireresistance
asfire-gradelinings.Thisismainlyusedwhereliningsstopatjunctionsbetweenwalland/orfloor
elements.Atthesejunctions,thewidthofthetimberframeworkisunprotectedbytheliningsandso
extrastuds,platesorjoistsareusedtoprovidefire-resistance.Thisispossiblebecausetimberofa
certainthicknessformsaninsulatingcharlayerasitburns.Thishelpsprotectandslowtheburning
processfortheremainingtimberthickness.Asaresult,itispossibletopredictablycalculateand
determinehowlongthetimberjointwilllastinafire.Thoughthisvariesaccordingtotimberdensity
andspecies,ingeneral,themorepiecesofsolidtimberaddedtothejoint,thelongerthejointwilllast.
Commonlocationswheresolidtimberisusedincludewalljunctionsandfloorjunctions(Figure13).
Forinformationonthedetailsofthisjointsincommonlocation,refertoSection5.4.

Roof Level

Timber blocks

used to maintain
Fire Resistance
Level

Ceiling Level

Floor Level
Timber blocks
used to maintain
Fire Resistance
Level

Subfloor Level

Figure 13: Common location of timber blocks that act as construction joints – elevation view.

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5.2 Principles for Achieving Sound Insulation in Timber-Framed Construction
Increasingmassofwallandfloorelementscanbeparticularlyusefulinreducingairborne
soundtransmission.Asimpleandeffectivemeansofdoingthisistoincreasethethicknessofwall
liningsandthisisoftenachievedwiththeabovementionedfire-gradelinings.
Isolatingonesideofawallelementfromtheother.Thisisalsoknownasdecouplingandcanbe
usefulinreducingbothairborneandimpactsound.Ofnote,itservestolimitthenoisevibrationfrom
onesideofthewalltotheotherandisaninherentfeatureofdoublestudcavitywallconstruction.

For treating weak

spots, suitable
sealants have fire
and sound ratings.

Avoidingrigidconnectionsbetweentheopposingsidesofisolated(decoupled)elements.
Thislimitstheoccurrenceofsoundbridgesthatwouldotherwiseallowsoundtotransmitfromone
sideofthewalltotheother.Ifrequiredforstructuralstability,sound-resilientstructuralconnectors
shouldbeusedandshouldgenerallyonlybeusedateachfloororceilinglevel.
Usingabsorptivematerialstofillwallcavitiescanreduceairbornesoundtransmission.Cellulose
fibre,glassfibre,polyesterormineralwoolisgenerallyusedforthispurpose.
Sealingsoundleaksattheperipheryofwallandfloorelementsorwherepenetrationsaremade
forelectricalandplumbingservices.Thisisparticularlyimportantbecausepenetrationscreateaweak
spotinthesystem.Flexiblesealantsareoftenusedinsuchsituationsandoftenhavebothafireanda
soundratingwhichenablesrequirementstobemet.
5.3 Sound- and Fire-Rated Wall Construction Systems
Timberframedconstructionsystemsthathavebeendevelopedtomeetthesefireandsound
principlesareshowninFigure14toFigure16andinclude:
• sound-andfire-resistantdoublestudwalls,i.e.forseparatingwalls(Figure14);
• fire-resistantsinglestud,externalcladwalls(Figure15);and
• fire-resistantbrickveneerexternalwalls(Figure16).
Theseandsimilarsystemsarecommonlyprovidedusingproprietaryliningandinsulationproducts.
EachproductmustbeassessedinordertoprovecompliancewiththeBCA.Asaresult,onlythemain
designthemesareshowninthedrawingsbelow.

Fire- and
sound-rated linings

Sound-rated
insulation


Figure 14: Fire- and sound-rated double stud separating wall systems – plan view.

Fire-rated linings

External cladding
material on battens

Sound-rated
insulation

Vapour barrier
V

Figure 15: Fire-rated external stud wall systems (outside only) – plan view.

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Non-fire-rated linings

External brick wall

Figure 16: Fire-rated external brick veneer wall systems (outside only) – plan view.

5.4 Solid-Timber Construction Joints
AsexplainedinSection5.1,solidtimberisusedasanequivalenttofire-gradelinings,themore
blocksusedthegreatertheFireResistanceLevelachieved.Thisisanimportantmeansofmaking
fire-resistingjointsbetweenwall,floorandceilingelementsintimber-framedconstruction.Avariety

ofcommonsituationsareshowninFigures17,18,19and20;eachsystemshowsdifferentwaysto
maintainthewalls’integrityandaredependentontheinstallerspreferenceandavailablesupportto
thelinings.
More solid timber
blocks = greater
fire resistance.

5.4.1 Non-Rated Walls Abutting Fire- and Sound-Rated Walls
Timberblockscanbeusedtocloseoffwallswhereinternalnon-ratedwallsabutfire-andsound-rated
walls.Theblockingcanbeintheformofstuds.Wherethenon-ratedinternalwallisloadbearing,the
timberblocksusedtomaintainfireresistancegenerallycannotbeusedtosupportload.

Non-fire-rated wall
Additional 45 mm solid
timber blocking
Fire- and
sound-rated linings

Flexible fire-grade
sealant

Figure 17: Junction between fire-rated and non-fire-rated and/or lower fire-rated wall – plan view.

Additional 45 mm solid
timber blocking
35 x 35 mm metal
angle applied to stud
Fire- and
sound-rated
linings


Non-fire-rated wall

Flexible fire-grade
sealant

Figure 18: Junction between fire-rated and non-fire-rated wall – alternative method using metal angles –
plan view.

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5.4.2 Non-Rated Floor Abutting Rated Wall
Non-ratedfloorsinterferewiththewallliningtotheseparatingwall.Inthiscasetimberblockscan
againbeemployed.Thefollowingdetailsanumberofoptionsthatcanbeutilisedandaregenerally
dependantonindividualchoiceortheframingsituation.Nooneoptionispreferred.
If fire strikes, floors
must be able to
collapse while
leaving separating
walls intact.

Inallcasesitisalsoimportanttonotethatintheeventofafire,theflooringandfloorjoistsmustbe
freetorotateawayfromtheseparatingwall.Thisrequiresthatthefloorsheetorboardsnottobe
continuousundertheseparatingwallframing.Itisrecommendedthatseparatepackersbeused,or
theflooringissawninthisregion.
Solid-TimberBlocking
Blockingistobesolidtimberandmeasureatleastthejoistdepth.ForaFireResistanceLevelof

60/60/60,thetimberblockingthicknessistobeminimumof45mm.
Structural blocking
(as required) to
support upper walls

Flooring not
continuous under
wall plate

Timber
blocking to
support
flooring

Flexible fire-grade
sealant
NOTE: In all cases, floors
must be able to collapse in
the event of fire and leave
the separating wall intact

Structural blocking
(as required) to
support upper walls
Flooring not
continuous under
wall plate

Floor joists
perpendicular

to wall

Blocking or steel angle
for fixing ceiling lining
were required
Flexible fire-grade
sealant
NOTE: Sacrificial timber blocks
are to be arranged so that they
are continuous. Where they are
joined, they must occur so that
a stud or block is directly
behind the joint

Timber packers

Flexible fire-grade
sealant

Floor joists parallel
to separating wall

Additional 45 mm solid
timber blocking

Fire- and
sound-rated linings

Timber packers


Flexible fire-grade
sealant
NOTE: Flooring may
require continuous
supported at perimeter

Floor joists
perpendicular
to wall

Joist
hanger
Additional 45 mm
solid-timber blocking
Fire- and
sound-rated linings

Figure 19: Joist parallel and perpendicular to wall, wall stud not continuous through junction – elevation
view.

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Flooring not
continuous under
wall plate

Engineered timber

(floor trusses)

Additional noggings
to support wall
linings

Flexible fire-grade
sealant
NOTE: Timber blocks are to be
arranged so that they are
continuous. Where they are
jointed they must occur so
that a stud or block is directly
behind the joint.

Flexible fire-grade
sealant

Engineered
timber floor
joists

Additional 45 mm
solid-timber blocking

Fire- and
sound-rated linings

Figure 20: Wall stud continuous through junction with timber blocks – elevation view.


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FirePocketsinSeparatingWall
Anothermethodistocreatepocketswithintheseparatingwallthatallowthejoiststobearonthewall.
Thisdetailcanbeachievedbyutilisingasimilartechniquediscussedfordoublejoists(refertosection
5.4.2.1)whereonecontinuoussolidtimberjoistthesamedepthofthejoistsystemprovidesthefire
protection.Whereitisrequiredtobejoined,itmustbebuttedclosely,andthejointmustbeatleast
100mmawayfromanyfirepocketformed.
Burning joists that
are free to rotate
don’t snag the wall
above.

Thefloorjoists,beingsolidtimber,I-beamsorfloortrusses,cannowbearontothetopofthewall.
Betweenthejoists,additionalsolid-timberblocksthesamedepthandthicknessastheinnerblocking
aretobetightlycut-in.Themainfloorjoistsarenottobenailedtoblocking,anynailingistooccurat
thebaseofthejoistintothewallplateonly.Thetimberpackerdirectlyabovethejoistthatsitsinthe
pocketistoberemovedforthepocketportionwidth.Thisistoallowthejoisttorotateinafireevent
andnotcatchthebottomofthewallabove(Figures21and22).

Flexible fire-grade
sealant

Timber packer
removed above
fire pocket


Timber packers
Flooring may require
continuous support
at perimeter

Flexible fire-grade
sealant

Floor joists

Flexible fire-grade
sealant

Additional 45 mm
solid-timber blocking
between joists

Solid-timber blocking

Fire- and
sound-rated linings

Figure 21: Fire pockets in separating wall – elevation view.
Joists perpendicular
to wall
45 mm
solid-timber
blocking

Timber packers must be

arranged so that the butt
joints are covered by facing
blocking. No joint is to occur
within 100 mm of a fire pocket

Fire pockets

Figure 22: Pockets created in separating wall to accommodate floor joists – perspective view from above.

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