MULTI-RESIDENTIAL
TIMBER FRAMED CONSTRUCTION
Class 1a
Buildings
DESIGN & CONSTRUCTION MANUAL
National Timber Development Council
PREFACE
CONTENTS
The deemedto satisfyprovisionsof the BuildingCode
ofAustralia(BCA96) describethe requirementsand
limitationsfor timberframedmulti-residential
buildings. Theseprovisionsallow timberframingin:-
Section 1 SCOPE
2
Section 2 ABBREVIATIONS, DEFINITIONS,
TERMINOLOGY
2
Section 3 BCA REQUIREMENTS
3.1 Performance Provisions
3.2 Deemed to Satisfy Provisions
3.3 Separating Walls
3.4 External Walls
3.5 Roof Lights
3.6 SmokeAlarms
5
5
5
6
7
7
7
Section 4 STRUCTURAL REQUIREMENTS
4.1 Timber Member Design
4.2 Noggings
4.3 Notches, Cuts and Holes
8
8
8
8
"
"
"
All Class 1 buildings
Class 2 buildingsto 3 storeys
(4 storeys wheregroundstorey is concrete/masonry
carparking)
Class 3 buildingsto 2 storeys.
This manualoutlinesthe BCA requirementsfor Class
1a buildingsand associatedClass 10 buildingswith
respectto fire separationand noise controland
describesthe materials,detailsand construction
practicesthat are recommendedto satisfythese
requirements.
The information provided will enable designers,
local authorities, developers and builders to
achieve practical and economical solutions for
Multi-Residential Timber Framed Construction
(MRTFC).
A companion publication ”MRTFC Design &
Construction Manual – Class 2 & 3 Buildings”
describes the requirements for these building
classifications.
The information, opinions, advice and
recommendations contained in this publication
have been prepared with due care. They are
offered only for the purpose of providing useful
information to assist those interested in
technical matters associated with the
specification and use of timber and timber
products.
Whilst every effort has been made to ensure that
this publication is in accordance with current
technology, it is not intended as an exhaustive
statement of all relevant data, and as successful
design and construction depends upon
numerous factors outside the scope of this
publication, the authors and publishers accept
no responsibility for errors in, or omissions from,
this publication, nor for specifications or work
done or omitted to be done in reliance on this
publication.
Section 5 FIRE SEPARATION
5.1 Fire Resistance Level (FRL)
5.2 Solid Timber at Intersections
5.3 Strengthened Joints
9
9
10
11
Section 6 SOUND CONTROL
6.1 Weighted Sound Reduction Index (Rw)
6.2 Wall Framing Options
12
12
13
Section 7 CONSTRUCTION PRACTICEAND
DETAILS
14
7.1 Sub-floor Separating Walls
15
7.2 Double Stud Separating Walls
16
Intersections between suspended floors
and separating wall
Bearers supported off separating wall
Non-aligned floors
Separating walls above ceilings
Intersections with internal walls
Intersection with brick veneer external wall
Non-aligned external walls
Intersection with lightweight clad external wall.
7.3 Staggered Stud Separating Walls
Intersections between suspended floors and
separating walls
Bearers supported off separating wall
Intersection with internal walls
Separating walls above ceilings
Intersection with brick veneer external wall
Non-aligned external wall
© FWPRDC 2000
Intersection with lightweight clad external wall.
First Edition - June 2000
7.4
7.5
7.6
7.7
Single Stud Separating Walls
External Walls
Plumbing and Electrical Services
Boxed Gutters
Section 8 FIXING OF LININGS
MRTFC Class 1a - Design & Construction Manual
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20
20
21
22
23
23
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26
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29
30
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1
1 SCOPE
2
This manualcontainsthe timberindustry’s
recommendationsfor the designand constructionof
timberframedClass 1a attacheddwellings(duplexes,
townhouses,villas etc) and associatedClass 10
buildings(carportsetc). It provides informationon
materialsand systemsthat have been developed,as
well as detailsand buildingpracticesthat are necessary
to satisfythe fire resistance,and soundcontrol
requirementscontainedin the “deemedto satisfy”
provisionof the BuildingCode ofAustralia(BCA96).
TERMINOLOGY
SCOPE
1
NOTE: This manual describes the requirements for
Class 1a attached dwellings and associated Class
10abuildings.
NOTE: Buildingswhich containseparate residential
units above or below one another, as well as side by
side or which have common space above or below
dwellings(ie. common ceiling spaces, common subfloor space, commercial car parking etc.) are
classified as Class 2 or 3. These are described in
supporting publication “MRTFC Design and
ConstructionManual– Class2 and3 Buildings”.
The constructiondetailsand practicesincluded,will
generallycover the majorityof situations. They
should,however be regardedas typical,with
modificationspermitted,as long as the requiredfire
and soundperformanceis maintained.
NOTE: It is not intendedthat this manualprovide an
exhaustive statement of all the methods or
construction details appropriate for this form of
construction. Although the majority of systems
available at the time of publication have been
included, manufacturers will continue to develop
new and alternative systems, and practices will
invariably evolve which meet either the deemed to
satisfyor performancerequirementsof the BCA.
CAULKING(FIREGRADESEALANT)
Fire gradematerialused to fill gaps at jointsand
intersectionsin fire gradeliningsto maintainthe fire
resistancelevel (refer also “IntumescentSealant”).
NOTE: Caulking material may also need to be
flexible to allow for movement and/or waterproof for
externalor wet area applications.
CLASS1
One or more buildings,whichin associationconstitute–
(a) Class1a – a singledwellingbeing– a detached
house;or
one or more attacheddwellings,each beinga
building,separatedby a fire-resistingwall,
includinga row house,terracehouse,town house
or villa unit; or
(b) Class1b – a boardinghouse,guest house,hostelor
the like with a total floor area not exceeding300 m2
and in whichnot more than 12 personswould
ordinarilybe resident;
whichis not locatedabove or below anotherdwellingor
anotherClass of buildingother than a private garage.
NOTE: Class 1a detached houses and Class 1b
buildings (small boarding houses) have no fire
resistanceandsoundcontrol requirements.
CLASS10
A non-habitablebuildingor structurebeing–
(a) Class10a – a non-habitablebuildingbeinga
private garage,carport,shed, or the like; or
(b) Class10b – a structurebeinga fence,mast,antenna,
retainingor free-standingwall, swimmingpool, or
the like.
DEEMEDTO SATISFYPROVISIONS
Provisionscontainedin Section3 of the BCA whichare
deemedto complywith the performancerequirements.
DWELLING
A Class 1a building
2 ABBREVIATIONS, DEFINITIONS,
TERMINOLOGY
FRL - FIRERESISTANCELEVEL
The fire resistance,expressedas a time (in minutes)that
a structuralmemberor part of a buildingmust
achieve with respectto -
The following abbreviationsand definitionsapplyin
the use of this manual.
(a) structuraladequacy - (ie. maintainstabilityand
adequateloadbearingcapacity)
BCA
BuildingCode ofAustralia1996 - Volume2, Class 1
and Class 10 BuildingsHousingProvisions.
(b) integrity -(ie. resist passageof flames,smoke and
hot gases)
BUILDINGSOLUTION
A solutionwhicheither:(a) complieswith the deemedto satisfyprovisionsof
the BCA or
(b) is an alternative solutionwhichcomplieswith the
performancerequirements.
2
(c) insulation- (ie. maintaina specified temperature
on the surface not exposedto fire)
and expressedin that order (e.g. FRL 60/60/60for
separatingwalls).
NOTE:A dash,for examplein 60/ - / - , meansthere is
no integrity or insulation requirement for that
memberor partof the building.
MRTFC Class 1a - Design & Construction Manual
FIRE-SOURCEFEATURE
NON-COMBUSTIBLE
(a)
the far boundaryof a road adjoiningthe
allotment;or
(b)
a side or rear boundaryof the allotment;or
(a) appliedto a material- meansnot deemed
combustible underAS 1530.1CombustibilityTests for Materials;and
(c)
an externalwall of anotherbuildingon the
allotmentwhichis not of Class 10.
FIREGRADELINING
Fire gradeplasterboardor a combinationof fire grade
plasterboardand fibre cementused to provide the
requiredFRL in a separatingwall or externalwall.
HABITABLEROOM
A room used for normaldomesticactivities,and –
(a) includesa bedroom,living room,loungeroom,
musicroom,televisionroom,kitchen,diningroom,
sewing room,study, playroom,familyroom and
sunroom;but
(b) excludesa bathroomlaundry, water closet,pantry,
walk-inwardrobe,corridor, hallway, lobby,
photographicdarkroom,clothes-dryingroom,and
other spacesof a specialisednatureoccupied
neitherfrequentlynor for extendedperiods.
INTUMESCENTSEALANT(INTUMESCENT
PUTTY)
A fire resistantmaterialused in fire gradelinings(at
joints,penetrationsetc) whichexpandswhen exposed
to fire to fill and/orseal gaps and maintainsthe required
fire resistancelevel.
MINERALWOOL (FIRERESISTANT)
Compressible,non-combustible,fire resistantmaterial
used to fill cavities and maintainthe fire resistanceor
restrictthe passageof smoke and gases.
NOTE: The mineral wool to be used in all
applications in this manual, must be fire resistant
and therefore must have a fusion temperature in
excess of 1160°C. ‘Rockwool’ type products
generally meet these requirements, whilst
‘glasswool’productsdo not.
To maintain FRL 60/60/60 the fire resistant mineral
wool must be a minimum width of 120 mm and
compressesto 85%of originalthickness.
MRTFC
Multi-ResidentialTimberFramedConstruction.
MRTFC Class 1a - Design & Construction Manual
2
TERMINOLOGY
FIRESTOP
Fire gradematerialused to close a gap or imperfection
of fit that occurswherea servicepassesthrougha firerated elementor system.
(b) appliedto constructionor part of a buildingmeansconstructedwhollyof materialsthat
are not deemed combustible.
PERFORMANCEREQUIREMENTS
Requirementsin the BCA whichstate the level of
performancewhicha buildingsolutionmust meet.
RESILIENTCHANNEL/MOUNT
Proprietarysupportfor liningsdesignedto improve
soundinsulationand reducesoundtransmission.
Rw
(refer “WeightedSoundReductionIndex”)
SEPARATINGWALL (PARTYWALL)
A wall that is commonto adjoiningClass 1a buildings
(refer Figure1 and Section3.2).
NOTE: Walls that are common to or between
adjoining buildings other than Class 1(a), or walls
between a Class 1(a) building and another
classificationare referred to as commonwalls or fire
walls (refer “MRTFC – Design & Construction
Manual– Class2 & 3 Buildings”).
STC (SOUNDTRANSMISSIONCLASS)
The methodof ratingthe airbornesoundtransmission
performanceof a wall or floor/ceilingelementprior to
1999.
NOTE: The acoustic ratings required by the BCA
(Amendment6 - 1999) are now called the “weighted
sound reduction index” with the symbol Rw,
consistentwithAS / NZS1276.11999.
Test results for buildings and building elements with
STC values in accordance with the 1979 version of
AS 1276 remain valid (the STC value being the Rw
value).
SITE
The part of the allotmentof land on whicha building
standsor is to be erected.
NOTE: Class1a buildingsmay be on their own
separate allotmentwithina group title, communitytitle
or Torrens title subdivision(ie. where the separating
wall is on the site boundary).Alternativelyseveral
Class1a buildingsmay be on a singleallotment,with
each dwellingsold underBuildingUnit or Strata title.
WEIGHTEDSOUNDREDUCTIONINDEX(Rw)
The ratingof soundinsulationin a buildingor building
elementas describedinAS/NZS1267.11999.
3
Parapets above combustible roof
TERMINOLOGY
2
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 5
dwelling 8
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
dwelling 11
dwelling 12
Private garages may be under
or within class 1a dwelling
dwelling 13
Attached carports or garages
(class 10 a)
FIGURE 1 - TYPICAL CLASS 1a BUILDINGS
4
MRTFC Class 1a - Design & Construction Manual
3 BCA REQUIREMENTS
PerformanceProvisions
The following summarisesthe BCA’s objectives and
performancerequirementsfor Class 1 and 10 buildings
with respectto:
a) Structure - withstandthe combinationof loads
and other actionsto whichthey may be reasonably
subjected.
b) DampandWeatherproofing – provide resistance
to moisturefrom the outsideand moisturerising
from the ground.
c) Fire Safety – protectbuildingsfrom the spreadof
fire and provide safeguardsso that occupantsmay
safelyevacuate.
d) HealthandAmenity
i) WetAreasnot to createunhealthy or dangerous
conditions
3.2
Deemedto SatisfyProvisions
The BCA contains“deemedto satisfyprovisions”that
are acceptableformsof constructionwhichcomply
with the performancerequirements.The simplestway
to obtainapproval or certificationfor a projectis to
complywith the deemedto satisfyprovisions.
For attachedClass 1a MRTFC projectsthe majorityof
the deemedto satisfyrequirements(as well as the
performanceprovisions)are the same as the
requirementsfor detachedhouses. The requirements
are the same for:-
• dampand weatherproofing
• kitchensand wet areas
• room sizes and heights
ii) Roomheightsto be suitablefor the intendeduse
• light and ventilation
iii)Provide facilitiesfor personalhygiene,
laundering,food preparationand cooking
• safe access.
iv) Provide adequatenaturaland artificial light
v) Provide adequateventilation
vi) Prevent unduesoundtransmissionbetween
dwellings.
e) Safe MovementandAccess
i) Provide safe accessto and withinthe building
ii) Restrictaccess(youngchildren)to swimming
pools.
A buildingsolutionmust satisfyall of the performance
provisionsof the BCA. The buildingmay eithersatisfy
the “deemedto satisfy”provisionsof the BCA (and as
describedin the manual)or be an “alternative solution”
whichcan be shown to satisfythe performance
provisions.
3
• structuraldesign(useAS 1684-1999‘Residential
TimberFramedConstruction)
BCA REQUIREMENTS
3.1
The BCA requirementsfor attacheddwellingswhich
are in additionto or differentfrom those for detached
dwellingsare:(a) fire separationbetweendwellings - separating
walls must be of fire resistingconstruction.
Externalwalls must also be fire resistingif close to a
boundaryor anotherbuilding.
(b) soundcontrol betweendwellings - separating
walls must reducesoundtransmission(noise).
NOTE: This manualcontainstimberframed systems,
construction details and building practices which
satisfy the “deemed to satisfy” fire separation and
soundcontrol requirementsof the BCA.
NOTE: For guidance on gaining approval for an
alternative solution using the performance
provisions of the BCA refer to MRTFC Information
BulletinNo. 2.
MRTFC Class 1a - Design & Construction Manual
5
3.3
SeparatingWalls
NOTE: Cavities to be maximum 50 mm width.
flashing, dpc etc to be provided to maintain
weatherproofing where cavitiesare packed.
To satisfythe BCA deemedto satisfyfire and sound
requirements,separatingwalls betweenClass 1a
dwellingsshall:(a) be continuousfrom footing(or concreteslab on
ground)to undersideof non-combustibleroof
covering or 450 mm above combustibleroof.
(refer Figure1).
(f) extendthroughto the outsideof and effectively
separatevoids in boxed eaves etc (refer Figure30).
(g) have a soundtransmissionclass of not less than:i) Rw 45 betweenhabitableroomsin adjoining
dwellings.
(b) have a fire resistancelevel not less than
FRL 60/60/60(-/60/60if non-loadbearing)
(refer Section5.1)
(c) not be crossedby timbermembers(or other
combustiblebuildingelements)other than roof
battens(maximumsize 75 x 50 mm).
BCA REQUIREMENTS
3
ii) Rw 45 betweenkitchensor wet areas in
adjoiningdwellings.
iii)Rw 50 (as well as resistanceto impactsound)
betweena kitchen,bathroom,WC or laundryin
one dwellingand a habitableroom in an
adjoiningdwelling.
NOTE: All intersections must be constructedso that
in the event of fire, floors, ceilings, roof, internal
walls etc (within the dwelling on fire) are able to
collapsebut leavethe separatingwallintact.
NOTE: The above BCA sound requirements should
be regarded as minimum regulatory standards.
Higher levels of sound resistance are recommended
to satisfyconsumerexpectations.
(d) have any void betweentop of wall and undersideof
roofing (ie. betweenbattens)filled with solid
timber, fire resistantmineralwool or other suitable
fire resistingmaterial.
(e) extendthroughto the outsideof externalwalls
(ie. have cavities in brick veneer externalwalls
packed with fire resistantmineralwool, solid
timberblockingor other suitablefire resisting
material- (refer Figure16).
Note:
These portions of wall 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
Boundary
Note: 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
900
mm
1800 mm
The portion of the
wall within 900 mm
of boundary FRL
60/60/60
dwelling 2
dwelling 3
dwelling 1
Wall within 900 mm of
boundary measured at
right angles to have FRL 60/60/60
dwelling 4
900
mm
Walls within 1800 mm of another
building to have FRL 60/60/60
FIGURE 2 - FIRE RESISTING EXTERNAL WALLS
6
MRTFC Class 1a - Design & Construction Manual
ExternalWalls
In all statesexcept SouthAustralia,externalwalls in
Class 1a buildingsare requiredto be fire-resistingif
less than 900 mm from rear or side boundariesor less
than 1800 mm from anotherbuilding.The clearances
are measuredat right angles(90°) to eitherthe
boundaryor the externalwall of anotherbuilding(refer
Figure2).
NOTE: State and Local authorities throughout
Australia may have planning regulations which
containdifferent sitingrequirements.
TheSouthAustralianHousingCoderequires: External walls (including those at an angle or
perpendicular to the boundary) of a Class 1a
building within 600 mm of the allotment boundary,
or within 1200 mm of another building on the same
allotment, shall be of fire-resisting construction to
the underside of non-combustibleroof lining or noncombustible eaves lining to resist the spread of fire
from the outside except where protected by a wall of
fire-resistingconstruction(e.g. a ‘wingwall’).
Fire resistingexternalwalls must have a fire resistance
level not less than FRL 60/60/60when measuredfrom
the outside.( - /60/60if non-loadbearing).
NOTE: Fire rated external walls in Class 1a
buildings do not require fire resistance from the
inside.
Fire resistingexternalwalls must extendto the
undersideof a non-combustibleroof covering or to a
non-combustibleeaves lining(refer Figure27).
3.5 Roof Lights
Roof lights,(skylightsetc) whichcontaincombustible
material,may be installedin a roof whichis requiredto
have a non-combustiblecovering provided:(a) the area of the roof light is not more than 20% of the
roof area
(b)the roof light is not less than 900 mm from the
allotmentboundary
(c) the roof light is not less than 900 mm from the
verticalprojectionof any separatingwall which
extendsto the undersideof the roof covering
(d)the roof light is not less than 1.8 m from any roof
light in anotherbuildingon the allotment.
3
BCA REQUIREMENTS
3.4
NOTE: Where any of these limitationsare exceeded,
the roof covering is regarded as combustible.
Separating walls would therefore be required to
project450mmabove the roof.
3.6 Smoke Alarms
The BCA requiresthat all Class 1a buildingshave
automaticsmoke alarmsinstalled.
Smoke alarmsmust complywithAS 3786 and be
connectedto mainspower.
Alarmsshall be installedon or near the ceiling(at least
one alarmper storey), locatedbetweeneach part of the
dwellingcontainingbedroomsand the remainderof the
dwelling.
NOTE: The intention of smoke alarms is to detect
smoke before it reaches sleeping occupants, wake
them,andgivethemtimeto evacuateto safety.
NOTE: Eaves soffit lining must be non-combustible
but it is not required to be fire rated or have a fire
resistance level. Normal fibre cement products are
acceptable.
Openings(doors,windows etc) in fire resisting
externalwalls must be protected.
The following are regardedas beingprotected:(a) self closingsolid core doors
(b)non-openablefire windows (FRL - /60/ -) to
habitablerooms.
(c) maximum900 x 600 mm windows with steel frame
and no openingsashesto non-habitablerooms.
(Note: Can be permanentlyvented).
(d)Translucenthollow glass blocks.
MRTFC Class 1a - Design & Construction Manual
7
Stud width
4 STRUCTURAL REQUIREMENTS
4.1
(W)
Stud depth
(D)
TimberMemberDesign
Timbermembersizes for Class 1(a) buildingsshall be
determinedin accordancewithAS 1684 -1999
ResidentialTimberFramedConstruction.
Stud
In separatingwalls and fire rated externalwalls the
studs and platesshall also be the size determinedfrom
AS 1684.The minimumsize of studs shall be 70 x 45
mm or 90 x 35 mm studs in loadbearingseparating
walls. 70 x 35 mm studs can only be used in nonloadbearingseparatingwalls.
C
The stud spacingin separatingwalls and fire rated
externalwalls shall not be greaterthan 600 mm.
B
E
A
A
Timberspeciesshall have an average dry densityof not
less than 450 kg/m3.
4
STRUCTURAL REQUIREMENTS
E
P
(Note: Normalsoftwood, cypressand hardwood
framingmaterialmeetsthis requirement).
F
Bottom plate
4.2
Noggings
Noggingsshall be providedin all loadbearingwalls at a
maximumspacingof 1350 mm. Noggingsmay be
staggered(by up to the noggingdepth).
NOTE: To achieve satisfactorysound performance
in double stud and staggered stud walls, noggings
between studs supporting linings to one dwelling
must be kept clear of studs and nogging supporting
the linings to the adjoiningdwelling(refer Figures 9
and19).
4.3
Notches,Cuts,Holes
Wherever possible,notches,cuts and holes shouldbe
avoidedin structuralmemberswithinfire rated walls.
Wherethese cannotbe avoided,sizes and spacings
shall be limitedto those inAS 1684 - 1999.
FIGURE 3 - CUTS, NOTCHES AND HOLES.
TABLE A
CUTS, HOLES AND NOTCHES IN STUDS AND
PLATES
DESCRIPTION
A
LIMITS
Distance between holes
and/or notches in stud
breadth
Minimum 3 x D
H
Hole (studs and plates)
Maximum 25 mm in
wide face only
C
Notch into stud breadth
Maximum 10 mm
E
Notch into stud depth
• Maximum 20 mm at
every fifth stud
• Maximum 20 mm for
diagonal bracing
• Up to 25 mm for
installation of bath
• Not permitted where studs
are designed as “not
notched”
F
P
8
Distance between
notches in stud depth
Minimum 12 x B
Trenches in plates
3 mm maximum
MRTFC Class 1a - Design & Construction Manual
5 FIRE SEPARATION
5.1
Fire ResistanceLevel
Separationwalls betweenClass 1 attacheddwellings,
must be constructedto limit the spreadof fire and allow
the occupantsto safelyevacuate. The level of fire
resistancerequiredby the BCA is for the separating
wall to remainstructurallyintactand not allow the
passageof flame,heat, smoke and hot gases for a
periodof at least 1 hour. This fire resistancelevel is
expressedas FRL 60/60/60(or FRL - /60/60for nonloadbearing).
WhereClass 1 buildingsare within900 mm of a side or
rear boundary, or closerthan 1800 mm to another
building(In SouthAustralia,within600 mm of
boundaryor within1200 mm of anotherbuilding),
externalwalls also requirea fire resistancelevel of
FRL 60/60/60(or - /60/60for non-loadbearing). The
FRL for an externalwall only requiresto be measured
from the outside.
To achieve the fire resistancelevel in timberframed
walls, fire gradeliningsare fixed to studs with all
joints,intersectionsand penetrationssealed.
Liningmanufacturers(in associationwith the timber
industry)have developedvarioussystemswhichhave
been testedand certified by recognisedtesting
authorities(CSIRO or BRANZ). FRL 60/60/60
separatingwalls have eithera singlelayer of 16 mm
thick fire gradeplasterboardeach side, or a layer of 13
mm fire gradeplasterboardplus a layer of 6 mm fibre
cementto both sides. (Manufacturer’s
recommendationsfor fixing sheetsmust be strictly
adheredto).
FIRE SEPERATION
5
To ensurethe fire resistanceis maintainedat joints,
intersectionsand penetrations,the variousbuilding
practicesand detailscontainedin this publication
shouldbe followed (refer Section7).
MRTFC Class 1a - Design & Construction Manual
9
5.2
SolidTimberat Intersections
Many of the constructiondetailsin this manual
incorporateadditionalsolid timber(blockingor extra
studs,joists,etc.) in lieu of the fire gradeliningto
protectthe timberframeand maintainthe fire
resistancelevel at intersectionsetc. This systemhas
been developedto simplifyand speedup the
constructionprocessby allowing all framingto be
completedand roof installedbeforefixing plasterboard
linings.
NOTE: Whentimberburns,it chars relativelyslowly
from the outside at a predictable rate. This allows
additional,sacrificial timberto be used in lieu of fire
gradelining, to protectstructural members.
To maintainFRL 60/60/60at intersectionsa minimum
of 45 mm thicknessof solid timber(minimumaverage
dry densityof 450 kg/m3) is required. This is in
additionto any structuralmemberwithinthe fire rated
wall.
NOTE: The timber used to maintain the FRL cannot
carry out a structural function within the separating
wall. It can however be used to support non-rated
floors or partitions. No additional fixing is required
(for ledgers etc.) other than required to support loads.
Figure4 shows typicaljunctionswhere45 mm
thicknesssolid timberis used in lieu of fire grade
lining.
NOTE: Any timber grade and species (hardwood,
softwood, LVL) commonly used for framing has an
average dry densityin excessof 450 kg/m3 and can be
usedfor blocking.
Separating walls
(double studs or staggered studs)
Fire grade linings
Non-rated partition
5
FIRE SEPERATION
1 x 45 or 2 x 35 mm studs to
maintain fire resistance where
fire grade linings do not
continue through intersection
4(a) - Typical intersections between separating wall and internal partition
Separating walls
(double studs or staggered studs)
Fire grade linings
Caulking
Non-rated timber floor
Additional 45 mm thick joist, ledger, trimmer
or blocking to maintain fire resistance
Nogging to
support edge
of lining
Joist/bearer to support upper wall
4(b) - Typical intersections between separating wall and timber floor
FIGURE 4 - TYPICAL JUNCTIONS WITH ADDITIONAL SOLID TIMBER
10
MRTFC Class 1a - Design & Construction Manual
5.3 StrengthenedJoints
Wherethe intersectionbetweenthe fire gradeliningsis
strengthenedby either:• 35 x 35 mm plasterer’s angle
• intumescentsealeror
• fibre cementliningcontinuedthroughjoint
Then the thicknessof solid timberto maintain
FRL 60/60/60can be reducedto 35 mm. Figure5
shows typicalintersectionswhichhave been
strengthenedand allow the use the reducedtimber
thickness.
35 mm x 35 mm plasterers’ angle
Caulking
Studs positioned to
support angles
Noggings or top
plate to support
edge of lining
5(a) - Using 35 x 35 mm Plasterer’s angles
Intumescent sealant
FIRE SEPERATION
5
Studs behind sealant
Noggings on top plate
5(b) - Using intumescent sealant
Fire grade plasterboard
Caulking
Fibre cement lining continuous
through intersection
Noggings at 600 mm
maximum centres if studs
are not at intersection
5(c) - Using continuous fibre cement lining
FIGURE 5 - STRENGTHENED JOINTS
MRTFC Class 1a - Design & Construction Manual
11
6 SOUND CONTROL
6.1
COMMENTARY:
WeightedSoundReductionIndex(Rw)
The BCA requiresthe weightedSoundReduction
Index (Rw) and the resistanceto impactin separating
walls as shown in Table B.
TABLE B BCA REQUIREMENTS
Rw AND SOUND IMPACT LEVELS FOR
SEPARATING WALLS
LOCATION
IMPACT
SOUND
RESISTANCE
Thereare two types of soundswhichneed to be
controlled. Theseare from airbornesourcessuch
as speech,musicalinstrumentsand loudspeakers
and the other beingimpactsources,such as
footstepsand the moving of furniture.
Soundtransmissioncan be reducedby:•
Rw
LEVEL
Increasingmass can be achieved by
increasingliningthicknessor densityor using
more layersof linings.
•
(b) All other separating walls.
SOIL AND WASTE PIPES
A waste pipe or other
penetration that serves or
passes through a separating
wall between houses –
(a) If the adjacent room is a
habitable room (other than
a kitchen); or
Required
50
•
Not Required
45
Not Required
45
SOUND CONTROL
6
•
12
Sealing/CaulkingVoids
Soundleaks can easilyoccurat the periphery
of walls and floors,or wherea hole is made
for electricityor plumbingservices. To
reducesoundleaks,all gaps in a wall or floor
must be thoroughlycaulked, or sealed.
30
NOTE: The BCA requirements for sound control
between dwellings listed above should only be
regarded as the absolute minimum to meet statutory
requirements. It is recommendedthat a minimum of
Rw 50 be providedand resistanceto impactsoundbe
considered in all separating walls. Rw 50 with
impact resistance is considered necessary to reduce
airborneand structure borne noise to an acceptable
level.
Test results for buildings or building elements with
STC values in accordance with the 1979 version of
AS 1276 remain valid. The STC value is the same as
the Rw value.
AvoidingRigidConnections
Rigidconnectionsbetweenadjoining
dwellingscan transmitsoundenergy. Where
connectionsare requiredfor structure
stabilityetc., resislientconnectorsshouldbe
used.
•
(b) if the room is a kitchen or
any other room.
UsingAbsorptive Material
Fillingthe cavity with absorptive insulation
material(cellulosefibre, glass fibre or
mineralwool) can reduceairborne
transmissionsubstantially, especiallywhen
the cavity is large.
•
Not Required
UsingCavity Construction(Isolatingwall
surfaces)
One of the most effective ways of reducing
soundtransmission(airborneand impact)is
to isolatethe wall surfaces of adjoining
dwellings. This is achieved throughthe use of
doublestud or staggeredstud wall.
SEPARATING WALLS
(a) Between a bathroom,
sanitary compartment,
laundry or kitchen in one
Class 1 building and a
habitable room (other than
a kitchen) in an adjoining
Class 1 building.
IncreasingMass
BuildingLayout
One of the simplestmeansof controlling
noise is to distancenoise sourcesfrom
sensitive receiving areas. Laundries,service
shafts,stairs and other noisy areas in
buildingsshouldbe locatedas far as possible
from sensitive living or sleepingareas.
Placingrelatively quiet areas such as
bedroomsor loungeroomsnext to each other
also helps to minimisethe noise reduction
requiredfor occupantsatisfaction. Care is
requiredin locatingthe windows to ensure
they do not face noisy areas and that there is
adequateseparationbetweenwindows in
adjoiningdwellings.
MRTFC Class 1a - Design & Construction Manual
6.2
Wall FramingOptions
For separatingwalls betweendwellingsit is
recommendedthat doublestud or staggeredstud
systemsbe used (refer Figure6). Theseare the only
systemswhichprovide adequateresistanceto impact
soundas well as airbornesound.
Two walls separated
by cavity (minimum
20 mm recommended)
Singlestud walls shouldonly be used in situations
wheresoundcontrolis not critical,such as in spaces,
below sub-floorsor betweengarages.
Wheresuspendedfloorsin adjoiningunits are at
differentlevels, it is recommendedthat only double
stud wall systemsbe used (refer Figure13).
Satisfactoryimpactsoundresistancecannotbe
achieved with staggeredstud walls or singlestud walls
(even with resilientchannels)wherefloorsare nonaligned.
Note: The various wall systems and fire grade lining
optionsare summarisedin tables C,D and E. Linings
to be fixed in accordance with manufacturers
recommendationsandas outlinedin Section8.
Studs are not required
to be in line
6(a) - Double stud walls
Adjacent studs to align
with opposite sides
Lining fixed to
every second stud
6(b) - Staggered stud walls
SOUND CONTROL
6
Resilient channels or
mounts when required
for sound insulation
6(c) - Single stud walls
FIGURE 6 - WALL FRAMING OPTIONS
MRTFC Class 1a - Design & Construction Manual
13
To satisfy the BCA requirements and meet consumer
expectations the following details and practices
should be adopted.
7 CONSTRUCTION DETAILS
AND BUILDING PRACTICE
Additional joists 45 mm
minimum thick to maintain
fire resistence
Additional 45 mm thick trimmer or blocking
to maintain fire resistence
Joists as required to transfer loads
from separating wall to masonry
Caulking
Caulking
Caulking
Sawcut
Sawcut
Sawcut
Solid timber as required
to transfer loads from
separating wall to
masonry
Bearer
Termite barriers
(through or over
masonry wall)
Joist
Bearer
Masonry wall minimum 90 mm wide
with attached piers
7(a) - Masonry wall taken up to joists
Additional joists 45 mm
minimum thick
Caulking
Caulking
Sawcut
Sawcut
Joists and bearers to
transfer loads from
separating wall to masonry
Caulking
Caulking
Sawcut
Sawcut
Joist
Minimum
45 mm thick
blocking
Bearer
Bearer may be either sheeted with
2 x 13 mm fire grade plasterboard
or additional 45 mm thick
timber blocking
7(b) - Masonry wall taken up to bearers
Nogging
Caulking
Joists, trimmer ledger
45 mm minimum thick
Caulking
Nogging
CONSTRUCTION & DETAILS
7
Bearer
45 mm thick blocking
or fire grade lining
between bearers
Note:
All details suitable for double stud or
staggered stud separating walls
7(c) - Separating wall supported off masonry wall
FIGURE 7 - MASONRY SUB-FLOOR SEPARATING WALLS
14
MRTFC Class 1a - Design & Construction Manual
7.1 Sub-FloorSeparatingWalls
Separatingwalls must be continuousfrom the ground
to the undersideof a non-combustibleroof or 450 mm
above a combustibleroof. Walls below suspended
groundfloorsmay be masonry(refer Figure7) or
timberframedwith fire gradelining(refer Figure8).
Timberframedsub-floorseparatingwalls may be either
loadbearingextensionsof the separatingwall above, or
alternatively non-loadbearinginfill walls between
structuralpiers.
Solid timber or framing to transfer wall loads to sub-floor wall
Caulking
Additional
45 mm thick joist
Sawcut
Caulking
45 mm thick blocking
Sawcut
Joist
Additional
blocking
(minimum
45 mm thick)
Bearer
Either 2 x 13 mm thick fire grade
plasterboard or additional 45 mm
thick timber to protect bearer
Single stud wall between posts
(termite resistant framing
below termite barrier)
DPC
Structural post or
pier (timber, brick or masonry)
Timber sole plate
Note:
This detail only to be used
where no termite hazard exists
8(a) - Single stud wall between concrete or masonry piers
Minimum 45 mm thick
blocking, ledger
or trimmer
Caulking
Caulking
Caulking
Caulking
Sawcut
Sawcut
Joist
Joist supported
off hangers or ledgers
1 x 16 mm fire grade plasterboard or
1 x 13 mm fire grade plasterboard plus
6 mm fibre cement to both sides
75 mm
7
CONSTRUCTION & DETAILS
45 mm
minimum
thick joists
or ledger
Solid timber to
transfer wall loads
to sub-floor wall
8(b) - Separating wall (double or staggered studs) supported off footing
FIGURE 8 - TIMBER FRAMED SUB-FLOOR SEPARATING WALLS
MRTFC Class 1a - Design & Construction Manual
15
7.2
DoubleStud SeparatingWalls
Separatingwalls may be constructedwith two
individualstud framedwalls (refer Figure9 and
Table C).
Note:
Refer figure 11-13 for floor
intersections and figure 14
for roof/ceiling intersections
NOTE: Complete isolation of the two structural
frames in double stud walls provides the best
airborneandimpactsoundresistance.
Intersectionsmust be constructedto maintainthe fire
resistancelevel and soundperformance. The
following typicaldetailsshow recommendedbuilding
practicefor doublestud separatingwalls:-
Fire grade linings
Figure9 - Doublestud walls (typical)
Acoustic insulation may be
provided (either between
studs in one leaf or in wall
cavity)
Figure10 - Two storey doublestud walls
Figure11 - Intersectionsbetweensuspendedfloors
and separatingwall
Figure12 - Bearerssupportedin separatingwall
Figure13 - Non-alignedfloors
Nogging may be staggered for
2 layer linings or where single
layer linings are fixed vertically
Figure14 - Separatingwalls above ceilings
Figure15 - Intersectionswith internalwalls
Figure16 - Intersectionwith brick veneer external
wall
Figure17 - Non-alignedexternalwalls
Figure18 - Intersectionwith lightweightclad
externalwall.
5 - 10 mm gap below lining
(refer manufacturer’s
recommendation) gaps to
be caulked
20 mm minimum cavity to
achieve Rw listed in table C
Overall width refer table C
Opposing studs in the
two leaves may be
in-line or offset
CONSTRUCTION & DETAILS
7
Studs
600 mm max c/s
Lining options
a. 6 mm fibre cement plus 13 mm fire grade plasterboard
both sides (fibre cement may be inner or outer layer)
Note:
Refer figure 15-18
or wall intersections
b.16 mm fire grade plasterboard to both sides
(13 mm in non-load bearing walls)
FIGURE 9 - DOUBLE STUD WALLS (FRL 60/60/60)
16
MRTFC Class 1a - Design & Construction Manual
TABLE C
DOUBLE STUD WALLS FRL 60/60/60
Fire Grade Linings
One layer 16 mm fire grade
to plasterboard both sides.
(loadbearing or non-loadbearing walls)
One layer 13 mm fire grade plasterboard
to both sides.
(non-loadbearing walls only)
6 mm fibre cement plus 13 mm fire grade
plasterboard to both sides.
(See Note 4)
NOTES:
Studs
(minimum size)
90 x 35 mm @
600 mm max. centres.
70 x 45 mm of
600 mm max. centres
(See Note 3)
90 x 35 mm a
600 mm max.centres
70 x 35 mm at
600 mm max. centres
90 x 35 mm @
600 mm max. centres
70 x 45 mm @
600 mm max. centres.
(70 x 35 mm in
non-loadbearing walls)
Insulation
Nominal Rw
(refer notes)
50 mm
53 - 55
Nil
47
50 mm
50 - 52
Overall Width
(20 mm cavity)
232 mm
192 mm
Nil
46
50 mm
53 - 55
Nil
45
50 mm
50 -52
Nil
45
50 mm
58 -61
Nil
53 - 54
50 mm
57 - 59
226 mm
186 mm
238 mm
198 mm
Nil
51 - 52
1. All of the above have “satisfactory resistance to impact sound”.
2. The nominal Rw ratings listed are based upon a 20 mm cavity between walls with acoustic insulation (where listed)
50 mm thick polyester 350 kg/m3. Different thicknesses and types of insulation will alter Rw values.
(Refer lining manufacturer for actual tested Rw values).
3. 70 x 35 mm studs are not allowed in loadbearing fire rated walls.
4. The fibre cement can be either the first layer (against the studs) or the second layer.
CONSTRUCTION & DETAILS
7
MRTFC Class 1a - Design & Construction Manual
17
Nogging behind edge
of lining
Studs continuous for
full 2 storey height
Caulking
Resilient structural
connections at
mid floor level
Note:
For load-bearing walls or
where length of 2 storey
wall exceeds 3.5 metres
additional lateral restraint
may be required
45 mm thick ledger
Note:
Isolating stairs from
wall provides superior
sound performance
10(a) - Studs continuous for two storeys
Caulking
Resilient structural
connections at
mid floor level
Note:
For load-bearing walls or
where length of 2 storey
wall exceeds 3.5 metres
additional lateral restraint
may be required
Blocking or framing to transfer
upper wall loads to lower wall
Note:
Isolating stairs from
wall provides superior
sound performance
CONSTRUCTION & DETAILS
7
10(b) - Upper wall supported off lower wall
FIGURE 10 - TWO STOREY DOUBLE STUD WALLS
18
MRTFC Class 1a - Design & Construction Manual
Note:
In all cases, floors must be able to collapse in the
event of fire and leave the separating wall intact.
Caulking
Caulking
Sawcut
Joists to transfer load
from upper wall to
lower wall
Sawcut
Caulking
Sawcut
Caulking
Sawcut
Joist
Additional 45 mm thick
joists or ledgers to
maintain fire resistence
Joist hanger
or angle
Upper wall supported directly
off lower walls
Caulking
Caulking
Fibre cement
may continue
through
Caulking
Joist
45 mm thick or 35 mm if
fibre cement continued
through intersection
Caulking
Floor truss
I beam etc.
Top chord may be
supported off ledger
Joist hanger
or angle
Caulking
Caulking
45 mm thick
solid timber
Fire grade linings
(all layers) must
continue through
intersection or 45 mm
thick solid timber provided
to maintain fire resistence
11(a) - Joists paralled to separating walls
45 mm thick
ledger
11(b) - Joists perpendicular to separating walls
FIGURE 11- INTERSECTIONS BETWEEN SUSPENDED FLOOR AND SEPARATING WALLS
MRTFC Class 1a - Design & Construction Manual
19
CONSTRUCTION & DETAILS
7
Note:
Upper wall must not
be supported off bearers
Bottom plate
upper wall
Compressed
mineral wool
Top plate
lower wall
Bottom plate
Studs each side of
bearer to support
wall plates
(45 mm thick)
45 mm thick
joists
Nogging
(45 mm thick)
Bearer
Bearer
Compressed
mineral wool
Top plate
lower wall
Fire grade lining
sealed against bearer
Slope top of bearer
to allow rotation in the
event of collapse
12(a) - Section / Elevation
Posts/joists directly
below to support
bearer
12(b) - Plan view
FIGURE 12 - BEARERS SUPPORTED OFF SEPARATING WALL
Caulking
Sawcut
Note:
Any of the floor intersection details
for double stud walls are suitable
for non aligned floors (refer figure 11).
Caulking
Sawcut
Additional 45 mm thick timber
to maintain fire resistence
CONSTRUCTION & DETAILS
7
Note:
Staggered stud and single stud
walls do not provide satisfactorily
sound performance where floors
are non-aligned.
FIGURE 13 - NON-ALIGNED FLOORS
20
MRTFC Class 1a - Design & Construction Manual
Cavity between top of
wall and underside of
roof to be filled with
compressed fire
resistant mineral wool
Single stud
wall
Truss
Note:
Refer to truss
manufacturers for
minimum bearing
requirements
Ceiling
Double stud or
staggered stud
walls
Figure 14(a) - Single stud wall
Notes:
1. Additional ledgers/battens may be required to
support ceilings.
2. Top of wall cavity may need to be sealed to prevent
moisture from entering cavity during construction.
3. These details are also suitable above staggered
stud walls.
Two nailed gable trusses.
Vertical truss members at
maximum 600 mm centres
70 mm minimum
width between
linings
Nogging to
support
edge of
lining
Batten
(where required)
to support ceiling
45 mm thick
ledger
Fire grade linings
as for separating
wall
Fire grade lining
may continue
through
14(b) - Separating wall continued up to roof
Compressed fire resistant
mineral wool
between battens
7
Compressed mineral
wool to fill irregularities
between truss and wall
14(c) - Sheeted trusses
FIGURE 14 - SEPARATING WALLS ABOVE CEILINGS
MRTFC Class 1a - Design & Construction Manual
21
CONSTRUCTION & DETAILS
Compressed fire resistant mineral wool
between roof battens
Nogging at 600 mm
spacing where no studs
at intersecting wall
Fire grade lining continuous
through joint
15(a) - Fire grade linings continuous
Nogging at 600 mm
spacing where no studs
at intersecting wall
Minimum 35 mm thick stud
Fibre cement first layer
continuous through joint
15(b) - First layer (fibre cement) continuous
2 x 35 mm or 1 x 45 mm studs to
maintain fire resistence.
1 x 35 mm or 1 x 45 mm if joint
reinforced with plasterers angle or
intumescent sealant (refer figure 5)
CONSTRUCTION & DETAILS
7
Additional studs
to fix linings
Additional stud
15(c) - Studs in intersecting wall used to maintain fire resistance
FIGURE 15 - INTERSECTIONS WITH INTERNAL WALLS
22
MRTFC Class 1a - Design & Construction Manual
Wall plate not to be continuous
across separating wall
Wall plate not to be continuous
across separating wall
Additional studs to
support wall linings
Additional studs to
support wall linings
Fire grade lining
Fire grade lining
45 mm thick solid timber blocking
Compressed mineral
wool to fill cavity
Vertical DPC
Vertical DPC
16(a) - Cavity blocked with timber
16(b) - Cavity filled with mineral wool
DPC and
fire-stopping
if required
Wall plate not to be continuous
across separating wall
Fire grade linings continued
through to brickwork
16(c) - Fire grade linings continued across cavity
FIGURE 16 - INTERSECTION WITH BRICK VENEER EXTERNAL WALL
See note
Note:
Although fire grade linings are not required
in external walls, the linings would normally
be extended to the next intersection or
construction joint
Fire grade lining
dpc
7
Minimum
45 mm thick
CONSTRUCTION & DETAILS
Cavities blocked with
mineral wool or solid
timber 45 mm thick)
FIGURE 17 - INTERSECTION WITH NON-ALIGNED EXTERNAL WALL
MRTFC Class 1a - Design & Construction Manual
23
Cladding
Mineral
wool
Breather
type
sarking
Cladding
Breather
type
sarking
Minimum
45 mm
thickstuds
Note:
Top and bottom plate to external
wall not to continue across
separating wall
Additional studs to
support wall linings
Fire grade
lining
Compressed fire resistant mineral wool
to fill any voids in external cladding
(e.g. lapped weatherboards)
CONSTRUCTION & DETAILS
7
18(a) - Non rated external wall
FIGURE 18 - INTERSECTION WITH LIGHTWEIGHT CLAD EXTERNAL WALL
24
MRTFC Class 1a - Design & Construction Manual
Cladding
Fire grade lining
Breather
type
sarking
Cladding
Breather
type
sarking
Note:
Any external cladding materials
(e.g. Timber weatherboards)
may be used over the top of
fire grade linings in fire rated
external walls
45 mm
thick studs
Additional studs to
support wall linings
Fire grade lining
Fire grade lining
Note:
Top and bottom plate to external wall
not to continue across separating wall
CONSTRUCTION & DETAILS
7
Figure 18(b) - External wall FRL 60/60/60
(measured from outside only)
MRTFC Class 1a - Design & Construction Manual
25
7.3
Staggered Stud SeparatingWalls
Separatingwalls may be constructedusing a singletop
and bottomplate (120 mm or 140 mm wide)with
alternatestuds staggeredto align with oppositeedges.
Fire gradeliningsare fixed to alternatestuds. (refer
Figure19 and Table D).
Note:
Refer figures 20,21,22 & 24 for
floor and ceiling intersections
Full width top plate (refer table D)
Isolationof the structuralframe(except for plates)
provides satisfactoryresistanceto impactsoundas
well as airbornesound.
Fire grade linings
NOTE: Staggered stud walls are not recommended
for separating walls between units where floors are
not aligned. Satisfactorysoundperformancecannot
be achieved at floorintersections. Doublestudwalls
are recommendedfor non-alignedfloors.
Noggings kept clear of studs
which support lining to
adjoining dwelling
The following typicaldetailsshow recommended
buildingpracticefor staggeredstud separatingwalls to
maintainfire resistanceand soundperformance:Figure19 - Staggeredstud walls (typical)
35 mm thick noggings on
edge between alternate studs
Figure20 - Two storey staggeredstud walls
Figure21 - Intersectionsbetweensuspendedfloors
and separatingwalls.
Figure22 - Bearerssupportedoff separatingwall.
Figure23 - Separatingwalls above ceilings.
Full width bottom plate
Figure24 - Intersectionswith internalwalls
Caulking
Figure25 - Intersectionwith brick veneer external
wall.
Figure26 - Non-alignedexternalwall.
Figure27 - Intersectionwith lightweightclad
externalwall.
5 - 10 mm gap below lining
(refer manufacturer’s
recommendation) gap to be
caulked
Overall width (refer table D)
Nogging between
alternate studs
7
CONSTRUCTION & DETAILS
300 mm 300 mm
600 mm
Lining options
a. 6mm fibre cement plus 13 mm fire grade plasterboard
both sides (fibre cement may be inner or outer layer)
Note:
Figures 23, 25, 26 & 27
for wall intersections
b. Single layer fire grade plasterboard both sides (16 mm
for loadbearing walls, 13 mm for non-loadbearing walls)
FIGURE 19 - STAGGERED STUD WALLS (FRL 60/60/60)
26
MRTFC Class 1a - Design & Construction Manual
TABLE D
STAGGERED STUD WALLS FRL 60/60/60
Fire Grade Linings
Insulation
One layer 16 mm fire grade
to plasterboard both sides.
(loadbearing or non-loadbearing walls)
One layer 13 mm fire grade plasterboard
to both sides.
(non-loadbearing walls only)
6 mm fibre cement plus 13 mm fire grade
plasterboard to both sides.
(See Note 5)
Nominal Rw
Studs
Top and
(refer notes) (minimum size) bottom plates
Overall
Width
50 mm
49 - 51
90 x 35
140 x 35
172 mm
Nil
less than 45
90 x 35
120 x 35
(see Note 2)
152 mm
less than 45
70 x 45
120 x 35
152 mm
50 mm
45 - 47
90 x 35 or
70 x 35
120 x 35
146mm
Nil
less than 45
(see Note 4)
50 mm
56 - 57
90 x 25
140 x 35
178 mm
Nil
50
120 x 35
(see Note 2)
158 mm
50 mm
55 - 56
120 x 35
158 mm
Nil
49
70 x 45
NOTES: 1. All the above have “satisfactory resistance to impact sound”.
.
2. 120 mm wide top and bottom plates with 90 mm wide studs do not allow
clearance for timber noggings. Studs in structural walls, designed in accordance with AS 1684, require solid nogging at 1350 mm
max. spacing. Studs in structural walls with no nogging or metal strapping require alternative design and certification.
3. The Rw values listed are based upon 50 mm thick polyester acoustic insulation 350 kg/m3. Different types of insulation will give
different values. Refer lining manufacturers for actual tested Rw ratings.
4. 70 x 35 mm studs are not allowed in loadbearing fire rated walls.
5. Fibre cement may be either first or second layer.
Nogging behind edge
of lining
Studs continuous for
2 storeys
Resilient structural connections
at mid floor level
Full width top and
bottom plates provide
lateral restraints
Refer figure 21 & 22 for
intersection details
Note:
Isolating stairs from
wall provides superior
sound performance
20(a) Studs continuous
for 2 storeys
20(b) Upper wall supported
by lower wall
FIGURE 20 - TWO STOREY STAGGERED STUD WALLS
MRTFC Class 1a - Design & Construction Manual
27
7
CONSTRUCTION & DETAILS
Note:
For loadbearing walls or where
length of two storey wall exceeds
3.5 metres additional lateral
restraint may be required
Joists/blocking
as necessary to
support wall above
Joists/blocking
as necessary to
support wall above
Caulking
Caulking
Caulking
Sawcut
Fibre cement first
layer may continue
through joint
Sawcut
Additional 45 mm thick joist or
ledger (35 mm if reinforced) to
maintain fire resistance
45 mm thick joists
(35 mm if reinforced)
to maintain fire
resistance
Upper wall supported directly off lower wall
Fibre cement first
layer may continue
through joint
Caulking
Floor trusses
may be supported
by top chord
off ledger
Caulking
Caulking
Sawcut
Sawcut
Hanger or
angle
45 mm thick solid timber
(35 mm if reinforced or
fibre cement continuous)
21(a) - Joists paralled to separating wall
45 mm thick
or 35 mm thick
if joint reinforced
or fibre cement sheet
continued through
(refer figure 5)
21(b) - Joists perpendicular to separating wall
Note:
Where ‘I’ beams or floor trusses are used, either fire grade
linings (all layers) must continue through intersection or
substituted with solid timber to maintain fire resistance.
FIGURE 21 - INTERSECTIONS BETWEEN SUSPENDED FLOORS ON SEPARATING WALL
CONSTRUCTION & DETAILS
7
28
MRTFC Class 1a - Design & Construction Manual
Blocking (additional joists) to transfer upper
wall loads to lower wall (not supported off bearer)
Upper wall supported
directly off lower wall
Bottom plate
45 mm thick joists
Caulking
Sawcut
Caulking
Additional joist
45 mm thick
Top plate
Seal around bearer
Compressed
mineral wool
Fire grade
linings
Fire grade
linings
Slope tops of bearers
to allow bearers to
rotate in the event of
collapse
22(b) - Timber blocking to transfer wall loads
Bearers supported off
additional studs (posts)
22(a) - Upper wall supported off lower wall
Notes:
1. Bearers must NOT be
continuous through wall
2. Upper wall must NOT be
supported off bearers
Studs to support
top plate and
wall above
Bearers
supported
off additional
studs (posts)
Seal around
bearer
Studs to support
top plate and
wall above
CONSTRUCTION & DETAILS
7
22(c) - Plan views
FIGURE 22 - BEARER SUPPORTED OFF STAGGERED STUD WALL
MRTFC Class 1a - Design & Construction Manual
29
45 mm thickness
(35 mm if reinforced)
Gap
Gap
Additional studs to
support linings
1 x 45 mm or
2 x 35 mm joists
Gap
Additional studs to
support linings
Gap
7
CONSTRUCTION & DETAILS
45 mm minimum
thickness (35 mm if
joint reinforced)
FIGURE 23 - INTERSECTION WITH INTERNAL WALLS
30
MRTFC Class 1a - Design & Construction Manual
Cavity between top of wall
and underside of roof
to be filled with compressed
fire resistant mineral wool
45 mm thick ledger
to support ceiling
and trusses.
Fire-rated wall
Truss
Use truss boots as
required to support
trusses on ledger
Nogging behind
edge of linings
Note:
Single stud walls or sheeted trusses may be used
in ceiling spaces above staggered stud separating
walls. Refer figure 14 for typical details.
FIGURE 24 - SEPARATING WALLS ABOVE CEILINGS
Top plate and bottom plate
must not be continued over
separating wall
Additional studs to
support wall linings
CONSTRUCTION & DETAILS
7
Cavity to be blocked with either
fire resistant mineral wool,
solid timber or fire grade linings
continued to masonry
(as for double stud walls - figure 16)
FIGURE 25 - INTERSECTION WITH EXTERNAL BRICK VENEER WALL
MRTFC Class 1a - Design & Construction Manual
31
Note:
Although fire grade lining
is not required in external walls,
the linings would normally be
extended to the next intersection
See note
Additional stud to
support lining
Compressed
fire resistant
mineral wool
and d.p.c.
FIGURE 26 - INTERSECTION WITH NON-ALIGNED EXTERNAL WALLS
Cladding
Mineral
wool
Breather
type
sarking
7
Cladding
Additional studs to
support wall linings
fire resistant
mineral wool
to fill voids in
external
cladding
CONSTRUCTION & DETAILS
Breather type
sarking
Top and bottom plate to
external wall must not
continue across
separating wall
Note:
External wall may be fire rated (from the outside) with
continuous fire grade lining inside cladding and sarking
FIGURE 27 - INTERSECTION WITH LIGHTWEIGHT CLAD EXTERNAL WALLS
32
MRTFC Class 1a - Design & Construction Manual
TABLE E
SINGLE STUD WALLS FRL 60/60/60
Fire Grade Linings
One layer 16 mm fire grade
to plasterboard both sides.
(13 mm in non-loadbearing walls)
6 mm fibre cement plus 13 mm
fire grade plasterboard to both sides.
NOTE:
Fixing
Insulation
Resilient channels
or mount to
one side
50
Nominal Rw
Studs
(refer notes) (minimum size)
49
90 x 35
Overall
Width
135 mm
(129 mm
for 13 mm
lining)
Nil
less than 45
Furring channels
with resilient
mounted clips
to one side
50
50
Nil
less than 45
Direct to
studs
Nil to
filled cavity
less than 45
90 x 35
122 mm
(116 mm
for 13 mm
lining)
Direct to
studs
Nil
47 - 49
90 x 35
128 mm
Nil
less than 45
70 x 45
108 mm
90 x 35
157 mm
(151 mm
for 13 mm
lining)
1. Lining fixed with resilient channels or mounts should face likely noise source (eg. wet areas) to provide impact sound resistance.
Single stud walls with linings fixed to studs should only be used in locations where sound insulation is not critical (eg.
between garages or in sub-floor or roof spaces above ceilings).
2. The nominal Rw ratings listed are based upon a 20 mm cavity between walls with acoustic insulation (where listed)
50 mm thick polyester 350 kg/m3. Different thicknesses and types of insulation will alter Rw values.
(Refer lining manufacturer for actual tested Rw values).
3. 70 x 35 mm studs are not allowed in loadbearing fire rated walls.
4. The fibre cement can be either the first layer (against the studs) or the second layer.
7.4
SingleStud SeparatingWalls
Wherenoise reductionis not requiredby the BCA (eg.
BetweenClass 10 a garagesor carports)or in situations
wheresoundtransmissionis less critical(eg. In subfloor and ceilingspaces),singlestud framedseparating
walls may be used. (referTable E).
Note: An acceptablelevel of sound transmissionloss
can only be achieved in single stud walls with the use
of resilient channels or resiliently mounted furring
channels. These systems however are only
recommended for single storey, single room
applications (e.g. wet areas) because sound
performancecannotbe maintainedat intersections.
CONSTRUCTION & DETAILS
7
MRTFC Class 1a - Design & Construction Manual
33
7.5
ExternalWalls
Externalwalls within900 mm of a side or near
boundaryor closerthan 1800 mm to anotherbuilding
are requiredto be FRL 60/60/60( -/60/60if nonloadbearing). (ReferFigure2) This fire resistance
level needsonly to be attainedfrom the outside.
Compressed mineral wool
45 mm thick blocking or
fire grade lining taken
up to roofing (where no
eaves lining provided)
FRL 60/60/60externalwalls can be either:•
Brickveneer (minimum90 mm thick)brickswith
any rated or non-ratedinternallinings.
•
2 x 13 mm fire gradeplasterboardto externalface
covered by waterproofcladding(may be
combustiblematerial).Any rated or non-rated
internallining
•
1 x 16 mm wet area fire gradeplasterboardto
externalface covered by waterproofcladdingfixed
to verticalor horizontalbattensat 600 mm centres.
10 mm standardplasterboardinternallining.
•
Any FRL 60/60/60wall systems(referTables C, D
and E) with fire gradeliningto both sides,with
externalface covered by waterproofcladding(may
be combustiblematerial).
Non rated
internal linings
Note:
Fire rating needs
only to be from
the outside
Cladding
Breather type
sarking
Fire grade lining
FIGURE 28 - FIRE GRADE LINING OR
BLOCKING CONTINUED UP TO ROOF
Fire rated wall to extendup to non-combustibleroofing
or non-combustibleeaves lining(refer Figure28 &
29).
Compressed fire resistant mineral wool
NOTE: Eaves linings are required to be noncombustiblebut not fire rated.Fibre cementproducts
satisfythisrequirement.
Detailingof intersectionsbetweenfire rated external
walls and separatingwalls is exactlythe same as for
non-ratedexternalwalls. (Fire resistanceof separating
wall to be effectively continuedthroughexternalwall
and any associatedcavity) (refer Figures17,18,25and
27).
NOTE: Suspendedfloors may be supporteddirectly
off rated or non-rated external walls. There is no
requirement for floors to collapse away from
externalwallsin the eventof fire.
CONSTRUCTION & DETAILS
7
Separatingwalls must effectively extendthroughany
void in ceilingsand eaves (refer Figure30).
Wherefloorsare non-alignedor wherea singlestorey
dwellingadjoinsa two storey dwelling,the separating
wall and externalwall above the lower roof shall be as
shown on Figure31. The separatingwall between
dwellingsor betweendwellingand ceilingspace shall
be FRL 60/60/60from both sides. The externalwall
above the lower roof requiresFRL 60/60/60measured
from the outsideonly. ( - /60/60for non-loadbearing
walls).
34
45 mm thick blocking where
fire grade lining not taken
up to roofing
Non rated
internal linings
Non combustible
eaves lining
(e.g. Fibre cement)
Masonry
90 mm
minimum
thickness
provides
FRL 60/60/60
Note:
Floor may be supported within
fire rated external wall
FIGURE 29 - FIRE RATED WALL
(MASONRY OR FIRE GRADE LINING)
TO NON-COMBUSTIBLE EAVES LINING
MRTFC Class 1a - Design & Construction Manual
Cavity between top of wall and underside of roofing to be
filled with compressed fire resistant mineral wool
Fire grade lining, and framing
to extend through eaves
Fire rated separating wall
extended to underside of
roofing
Non fire-rated ceiling
Non-combustible eaves lining
Fire-rated separating wall
Fire rated separating wall
to be continued through
timber wall and cavity
(refer figure 16, 17, 18, 25 & 27)
FIGURE 30 EXTENDING SEPARATING WALL
THROUGH EAVES
Fire grade lining
Breather type sarking
External cladding
Note:
Internal fire
grade linings may
not be necessary
above roof but
are generally
continued up to
ceiling
Note:
The external wall above a lower
roof to have FRL 60/60/60
measured from the outside
Flashing
45 mm thick blocking or ledger
Mineral wool between
battens
Fire grade linings to
separate unit from
ceiling space
Caulking
CONSTRUCTION & DETAILS
7
Ledger to support ceiling
Sawcut
FIGURE 31 EXTERNAL WALL ABOVE LOWER ROOF
MRTFC Class 1a - Design & Construction Manual
35
7.6
Plumbingand ElectricalServices
The installationof plumbingor electricalservicesin
separatingwalls have the potentialto reducethe fire
resistanceand soundperformance. Wherepossible
these servicesshouldnot be locatedwithinfire
resistantwalls (ie. placedin adjoiningpartitions,
ducts,or over the face of fire gradelinings(behind
battenedout false wall).
300 mm
min.
300 mm
min.
NOTE: Where plumbing services are required on
noise sensitive walls, it is recommendedthat a false
wall be built in front of the fire and sound-rated wall
andthe plumbingbe placedintothisfalsewall.
Whereserviceswithinseparatingwalls cannotbe
avoided,the integrity of the wall must be maintained
for both fire resistanceand soundinsulation. The
following practicesshouldbe adopted:-
Not more than one electrical recess in
each wall face between any two studs
(a) All holes,gaps or other irregularitiesassociated
with penetrationsthroughfire-ratedelementsmust
be sealedor must seal duringa fire.
(b) Plumbingfittingsand/orelectricaloutletsshould
preferablynot be back to back (ie. penetrateonly
one face betweentwo studs).
Gap between baffle and opposite
studs in staggered stud walls
FIGURE 32 BAFFLE BETWEEN ELECTRICAL OUTLETS
OR SWITCHES
(c) Electricaloutletswhichare back to back, should
have eitherfire rated boxes (with intumescent
backing)or be installedwith 16 mm thick fire
gradeplasterboardbaffle extending300 mm above
and below fittings(refer Figure32).
16 mm fire grade
plasterboard baffle
(d) Back to back plumbingpenetrationsshouldbe
separatedby a 16 mm fire gradeplasterboard
baffle extending300 mm above and 300 mm
below penetration. 50 mm thick acoustic
insulationshouldalso be installed(refer Figure
33).
(e) Penetrationsfor servicesshouldbe kept a
minimumof 50 mm from studs.
Acoustic
insulation
CONSTRUCTION & DETAILS
7
Timber support
battens
50 mm
minimum
Acoustic insulation
between plumbing
fixtures and fittings
300 mm
Wet area sealant
(h) Baths,shower bases,sinks,basinsmust not be
recessedinto fire rated walls. Fire gradelinings
must be continuousbehindfixtures(refer Figure
34).
NOTE: Plastic pipes and fittings generally have
bettersoundperformancethanmetal.
Wet area sealant
16 mm fire grade plasterboard baffle
(f) Pipes must not be fixed to linings.
(g) Pipes shouldbe supportedoff battensbetween
studs or kept clear of studs with resilientmounts).
16 mm fire grade
plasterboard baffle
Resilient mounts
300 mm
Fire grade linings
Timber battens
FIGURE 33 - BAFFLE AND INSULATION BETWEEN PLUMBING OUTLETS
36
MRTFC Class 1a - Design & Construction Manual
Void created by
battens can be
used for services
Fire grade lining
(e.g. 16 mm fire
grade plasterboard)
Lining board
suitable
for wet areas
Timber batten
Timber support
batten fixed to
studs
Edge of bath/
shower not to
be recessed
into fire-rated wall
34(a) - Edge of bath
Fire grade linings
(e.g. 6 mm fibre cement plus
13 mm fire grade plasterboard)
Lining board suitable
for wet areas
Vanity or kitchen unit
not to be recessed
into fire-rated wall
Timber support
batten fixed to
studs
34(b) - Vanity or kitchen bench
Lining board suitable
for wet areas
Fire grade linings
CONSTRUCTION & DETAILS
7
Flashing fixed to
face of rated wall
Caulking to 5-10 mm gap
34(c) - Wet area floors
FIGURE 34 - WET AREA INSTALLATION
MRTFC Class 1a - Design & Construction Manual
37
7.7
BoxedGutters
Figure35 shows typicaldetailsfor boxed guttersat
separatingwalls.
45 mm thick blocking
between trusses
Bottom chords extended
(refer truss manufacturer)
35(a) - Roof framing on top of
separating wall (not to be continuous)
Hanger (truss boot)
45 mm thick ledger
35(b) - Roof framing supported off
hangers and ledgers
Breather type sarking
Cladding
Flashing
Note:
Bottom chord extended to box
gutter width (refer truss manufacturer)
CONSTRUCTION & DETAILS
7
Fire
grade
linings
Hanger (truss boot)
45 mm thick ledger
35(c) - Box gutter at parapet or for lower roof
FIGURE 35 - BOX GUTTERS
38
MRTFC Class 1a - Design & Construction Manual
8 FIXINGS OF LININGS
To achieve FRL 60/60/60in separatingwalls the
following fire gradeliningsand required:(a) LoadbearingWalls
- 1 x 16 mm fire gradeplasterboardto both faces
or
- 1 x 13 mm fire gradeplasterboardplus 1 x 6 mm
fibre cementto both faces (eithersheet fixed
first)
A gap of between5 and 10 mm shall be kept at the
bottomof fire gradeliningsat floor level. Gap to be
caulked with a fire resistantsealer.
NOTE: Caulking should generally be flexible to
allow for timber movement. Non-flexible caulking
(eg. Vermiculite plaster) may be used to seal gaps
between lining and concrete floors where seasoned
framingis used.
(b) Non-LoadbearingWalls
- 1 x 13 mm fire gradeplasterboardto both faces
(or eitherof the loadbearingoptions).
Differentliningmanufacturershave different
requirementsfor nail sizes and spacings. Liningsmust
be installedstrictlyin accordancewith manufacturer’s
instructions.
Internaland externalcornerjunctionsmust be arranged
to provide supportto both liningboards.Additional
studs or noggingsmay be required.
All verticalbutt jointsshall be on studs with joints
staggered. (ie. sheetson same face as well as sheetson
the oppositeface must not have verticaljointson the
same stud).
NOTE: Staggered nogging may be used for dual
layer systems, or where single layers are fixed
verticallywithno horizontaljoints.
Wheremultiplelayer liningsare used, horizontaland
verticaljointsshall be staggered. Sheetscan be fixed
horizontally, verticallyor a mixtureof both. The fibre
cementsheetsmay be eitherthe first or secondlayer.
NOTE: In FRL 60/60/60systemsfibre cement sheets
maybe eitherfirst or secondlayer.
At internalwall junctionsand at intersectionsbetween
separatingwalls and ceilings,any gaps betweenlinings
shall be sealedwith flexible fire resistantsealer.
NOTE: (ReferFigure 4 for the use of timberblocking
and Figure 5 for strengthening of joints with either
intumescent putty, plasterer’s angle or continuous
linings.
FIXING OF LININGS
8
MRTFC Class 1a - Design & Construction Manual
39
Studs at 600 mm
centres
Vertical joints
staggered
Nail spacings to manufacturers’
requirements
36(a) - Single layer fire grade plasterboard fixed horizontally
Note:
Vertical joints on opposite
faces to be staggered
(i.e. Not on the same stud)
Studs at 600 mm
centres
Joints centred on
stud
Nail spacings to manufacturers’
requirements
36(b) - Single layer fire grade plasterboard fixed vertically
Vertical joints
staggered
Nail spacings to manufacturers’
requirements
8
Nail spacings to manufacturers’
requirements
FIXING OF LININGS
36(c) - Fibre cement in conjunction with fire grade plasterboard
FIGURE 36 - FIXING OF LININGS
40
MRTFC Class 1a - Design & Construction Manual
MULTI-RESIDENTIAL
TIMBER FRAMED CONSTRUCTION
For informationregarding
MRTFCpleasecontact:
New South Wales - TDA
Timber Development Association of NSW
13-29 Nichols Street, Surrey Hills
New South Wales 2010
Telephone (02) 9360 3088
Fax (02) 9360 3464
Queensland - TRADAC
Timber Research And Development Advisory Council
500 Brunswick Street, Fortitude Valley
Queensland 4006
Telephone (07) 3358 1400
Fax (07) 3358 1411
South Australia - TDA
Timber Development Association of South Australia
113 Anzac Highway, Ashford
South Australia 5035
Telephone (08) 8297 0044
Fax (08) 8297 2772
Victoria - TAC
Timber Advisory Centre
180 Whitehorse Road, Blackburn
Victoria 3130
Telephone (03) 9877 2011
Members of the
National Timber Development Council
ATIF - Australian Timber Importers Federation
Fax (03) 9877 6663
FIAT - Forest Industries Association of Tasmania
Western Australia - TAC
FIFWA - Forest Industries Federation (Western Australia) Inc.
FPA - New South Wales Forest Products Association Ltd.
FWPRDC - Forest & Wood Products Reseach & Development Corporation
Timber Advisory Centre of Western Australia
55 Salvado Road, Subiaco
Western Australia 6008
Telephone (08) 9380 4411
Fax (08) 9380 4477
NAFI - National Association of Forest Industries
PA - Pine Australia Ltd.
Tasmania - TTPB
PAA - Plywood Association of Australia Ltd.
Tasmanian Timber Promotion Board
Suite 22, 11 Morrison Street, Hobart,
Tasmania 7000
Phone (03) 6224 1033
QTB - Queensland Timber Board
TDA (NSW) - Timber Development Association (New South Wales) Ltd.
Fax (03) 6224 1030
TDA (SA) - Timber Development Association (South Australia) Inc.
Plywood Association of Australia
TPC - Timber Promotion Council of Victoria
3 Dunlop Street, Newstead
Queensland 4006
Phone (07) 3854 1228
TRADAC - Timber Research and Development Advisory Council (Qld)
VAFI - Victorian Association of Forest Industries
Fax (07) 3252 4769
Pine Australia
FOREST&WOODPRODUCTS
830 High Street, Kew East
Victoria 3102
Phone (Free Call) 1800 007 463
RESEARCH & DEVELOPMENT CORPORATION
This publication is a joint venture between the National Timber Development Council
and the Forest and Wood Products Research and Development Corporation.
The FWPRDC is jointly funded by the Commonwealth Government and the
Australian forest and wood products industry.
© FWPRDC 2000 ,
Printed June 2000
Fax (03) 9859 2466
web
www.timber.org.au/mrtfc