08

Stairs, Balustrades
and Handrails
Class 1 Buildings - Construction
Technical Design Guide issued by Forest and Wood Products Australia


01

04

09

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

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

Timbe
r Floo
ring
for inst

Desig

n guide

Technica

l Desi

Technical Design Guide issued by Forest and Wood Products Australia

gn Guid

e issu

ed by

Forest

allatio
n

and Woo

d Prod

ucts

Australia

TechnicalDesignGuides
A growing suite of information, technical and
training resources created to support the use of

wood in the design and construction of buildings.
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 Noise Transport Corridor Design Guide
#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.
ISBN978-1-921763-16-8
Preparedby:
ColinMacKenzie
TimberQueenslandLimited
Firstproduced:April2007
Revised:May2012

© 2012 Forest and Wood Products Australia Limited.
All rights reserved.
ThesematerialsarepublishedunderthebrandWoodSolutionsbyFWPA.
IMPORTANT NOTICE
Whilstallcarehasbeentakentoensuretheaccuracyoftheinformation
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wellasanyothercontributorsmakenorepresentationsorgiveanywarranty
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Table of Contents

Introduction

5

1. TypesofStairConstruction


6

1.1 StraightStairs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.2 StraightStairswithIntermediateLanding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.3 NewelStairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.4 OpenNewelStair. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.5 Dog-legStair. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.6 Winders. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
1.7 GeometricalStairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2. BCARequirements

10

2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
2.2 Stairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
2.3 BalustradesandHandrails . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
3. MaterialsforExternalStairsWithoutRiserBoards(OpenStairs)

13

3.1 TimberDurabilityandSpecies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
3.2 TimberGrade. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
3.3 MoistureContent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
3.4 JointPriming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
3.5 CorrosionProtectionofFasteners. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
3.6 TermiteProtection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
3.7 SlipResistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
3.8 Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
4. MaterialsforInternalStairs–WithandWithoutRiserBoards(OpenandClosedStairs)18
4.1 TimberDurabilityandSpecies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

4.2 TimberGrade. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
4.3 MoistureContent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
4.4 TermiteProtection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
4.5 SlipResistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
4.6 SpanTables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
5. StairConstructionProcedure

21

5.1 MarginTemplateandPitchBoard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
5.2 MarkingOutStrings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
5.3 HousingStrings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
5.4 StringEndJoints. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
5.5 StepBolts(TieBolts) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
5.6 Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

#08 • Stairs, Balustrades and Handrails Class 1 Buildings – Construction

Page 3


6. BalustradesandHandrails

31

6.1 Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
6.2 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
6.3 MemberSizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
6.4 Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
7. Weathering,FinishesandMaintenance


38

7.1 ExternalStairsandBalustrades . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
7.2 InternalStairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Appendices

40

AppendixA–Glossary

40

A1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
A2 MembersinaStaircase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
A3 MembersinaBalustrade. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
A4 ConstructionTerms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
AppendixB–StairCalculations

43

B1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
B2 Example1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
B3 Example2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
B4 Example3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
B5 HeadroomforStairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
B6 PracticalMethodforCalculatingNumberofRisesandtheRise . . . . . . . . . . . . . . . . .49
B7 QuantityCalculations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
AppendixC–TotalRiseCalculations–SlopingGround


51

C1 DeterminingTotalRiseonSlopingGround . . . . . . . . . . . . . . . . . . . . . . . . . . . .51

#08 • Stairs, Balustrades and Handrails Class 1 Buildings – Construction

Page 4


Introduction
This guide covers
stairs with straight
flights, with or
without risers for
external and internal
use and balustrades.

Staircaseandbalustradeworkisconsideredtobeaspecialisedsectionofcarpentryand
joinery.Thisdocumentcoversstairswithstraight flights, with or without risers for external
and internal use and balustrades.
Internalstairsareoftenpreparedinaworkshopmakingfulluseofavailablemachinesandequipment.
Interiorstairsmaydifferconsiderablyindesign,fromsimplestraightflights,commonlyusedin
domesticwork,tomoreelaboratestairsconstructedpurposelyasanattractivefeatureinpublicand
commercialbuildingsandinelaboratehomes.
Exteriorstairsarecommonlybuiltfromtreatedsoftwoodanddurablehardwoodswhileinteriorstairs
arecommonlybuiltfromjoinery-qualitytimbercutandseasonedespeciallyforstairs.Thefinishfor
exteriorstairsisgenerallypaintandinteriorstairsisoftenclearpolish,lacquer,etc,thereforeboth
materialandworkmanshipshouldbeoftheveryhigheststandard.
Theconstructionproceduredescribedherewouldbemoreorlessgeneralforallstairsofeither
conventionalorcontemporaryconstruction.

Atanearlystageintheconstructionofabuildinghavingexteriorand/orinteriorstairs,adecisionwill
havetobemadeonthelengthofthestairstodeterminethelocationofanyfoundations,concrete
pads,etc,andtheopeningrequiredinthefloortoaccommodateinternalstairsandprovidesufficient
headroom.Also,beforethetimberforthestairscanbeordered,itwillbenecessarytoknowthelength
ofthestring,newels,landingtrimmers,joists,etc,andthenumberoftreadsandrisersrequired.Refer
toAppendixBforthecalculationsneededtodeterminethesefacts.
Scope
Thisguideisintendedtobeusedbythebuildingindustryforthedesign,practicesandconstruction
oftimberstairs,handrailsandbalustrades.Informationwithrespecttobothinternalandexternal
stairsisprovided.Also,bothopenstairs(norisers)andclosedstairs(withrisers)arecateredfor.
Recommendationsarealsoprovidedontimberspeciesselection,durabilityandfinishing,etc,and
examplestaircalculationsaregiveninAppendixBandC.
Disclaimer
Theinformation,opinions,adviceandrecommendationscontainedinthispublicationhavebeen
preparedwithduecare.Theyareofferedonlyforthepurposeofprovidingusefulinformationtoassist
thoseinterestedintechnicalmattersassociatedwiththespecificationanduseoftimberandtimber
products.Whilsteveryefforthasbeenmadetoensurethatthispublicationisinaccordancewith
currentpracticesandtechnology,itisnotintendedasanexhaustivestatementofallrelevantdata.
Assuccessfuldesignandconstructiondependsuponnumerousfactorsoutsidethescopeofthis
publication,theauthorsandpublishersacceptnoresponsibilityforerrorsin,oromissionsfrom,this
publication,norforspecificationsorworkdoneoromittedinrelianceonthispublication.
Regulatory Requirements

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


ThispublicationfocusesontraditionalpracticesandcurrentrelevantBuildingCodeofAustralia(BCA)
requirements.FromtimetotimetheBCAisamendedandstatesmayalsovaryrequirements.Users
ofthisGuideshouldmakethemselvesawareofanychangesordifferencesandshoulddevelopafull
understandingoftheresultingimplications.OnlyonthisbasisshouldthisGuidebeused.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings – Construction

Page 5


1

Types of Stair Construction

Thedesignandconfigurationofstairscandiffermarkedlydependinguponspace
availability,functionalityanddesiredappearance.Thissectiondescribesdifferenttypesof
stairconfigurationsandthevariouscomponentsofthese.
ThecommontypeofstairconstructionistohousetreadsintostringersasshowninFigure1.1.Flights
maybeconstructedwith‘opentreads’withoutrisersor‘closedtreads’withriserboards.

Figure 1.1: Common stair construction.

Open tread stairs are
recommended for
external use.

Closedtreadstairsandopentreadstairsaresuitableforbothexternalandinternaluse.However
opentreadstairsarerecommendedforexternalusebecausetheygivebetteraircirculationallowing
thetimbertodryoutmorequicklyandthereforeimprovedurability.Metalanglebracketsmayalsobe
usedratherthanhousinginthetreads.

Asanalternativetotimber,metalmaybeusedforstringers.Metalstringsareoftenusedinexternal
locations,butcanalsobeusedforinternalstairs.Theyareavailableinsomestateswitha‘stock’rise
andgoingorcanbeorderedwithaspecificriseandgoing.
Dependingontheapplication,flightscanbeconfiguredinvariousways.Thefollowingillustratessome
ofthese.
#08 • Stairs, Balustrades and Handrails Class 1 Buildings – Construction

Page 6


1.1 Straight Stairs
Asingleflightofstairshavingalltreadsparalleltooneanother.Thisformofstair,whichiswidelyused
fordomesticconstruction,hasnolandingandmaybeenclosedbetweentwowallsorbuiltagainst
onewallandtheothersideopenwithnewelsandbalustrade(Figure1.2).

Figure 1.2: Straight stairs.

1.2 Straight Stairs with Intermediate Landing
Stairshavingmorethanoneflightrisinginthesamedirectionandalltreadsparallel(Figure1.3).

Figure 1.3: Straight stairs with landing.

1.3 Newel Stairs
All stairs which
include newel posts
in their construction
are referred to as
newel stairs.

Allstairswhichincludenewelpostsintheirconstructionarereferredtoasnewelstairs.Thenewels

supportthehandrailsand/orbalustradeandmayalsosupportthelandingsandstrings.Figures1.2
and1.3illustratestraightnewelstairs.Figures1.4,1.5and1.6showotherformsofnewelstairs.

Figure 1.4: Newel stairs.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings - Construction

Page 7


Figure 1.5: Dog-leg newel stairs.

Figure 1.6: Newel stairs with wide landing.

1.4 Open Newel Stair
Anopennewelstairisalsoreferredtoasan‘openwellstair’oran‘openwellnewelstair’.Thisform
ofstairhastwoormoreflightswhichreturnoneachotherformingaverticalspacecalledthewell
(Figures1.4and1.5).
1.5 Dog-leg Stair
Anewelstairhavingtwoflightsbuiltat180°toeachotherfromahalf-spacelanding.Theouterstring
oftheupperflightistenonedplumbabovetheouterstringofthelowerflightandbothtoasingle
commonnewel(Figure1.5).Thistypeofstairisnotcommonlyusedinhousing.
1.6 Winders
Triangularshapedtreadsusedtogainheightandinplaceofaquarter-spacelandingina90°turnstair.
Amaximumofthreewindersarefittedper90°andthecentreoneisnameda‘kite’winderbecauseof
itsshape(Figure1.7).

00

Figure 1.7: Stairs with winders or isolated step.


#08 • Stairs, Balustrades and Handrails Class 1 Buildings – Construction

Page 8


1.7 Geometrical Stairs
Astairwhichchangesdirectioninplanwithoutusingnewels.Thestringsandhandrailsarecontinuous
fromfloortofloor,thecurvedportionsbeingeithercutfromsolidtimber(sawkerfed),stavedor
laminated(Figure1.8).

Figure 1.8: Geometrical stairs.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings - Construction

Page 9


2

BCA Requirements
TheregulatoryrequirementsforstairsandbalustradesprescribedbytheBCAareprimarily
concernedwithaddressingthesafetyissuesassociatedwithslips,tripsandfalls.Thebasic
BCArequirementsrelatingtostairandbalustradegeometry,openingwidth,landingsizes,
handrailheights,etc,needtobestrictlyfollowedtoensureregulatorycompliance.
2.1 General

Stairs, handrails
and balustrades
must be designed

and constructed
to comply with the
loadings given in
AS 1170 Part 1.

ForallClassesofbuildings,stairs,handrailsandbalustradesarerequiredtocomplywiththeBuilding
CodeofAustralia(BCA).TheBCArequirementsincludedesignandconstructionprovisionsforthe
variouscomponentsincludingcompliancewiththeloadingprovisionsofAS1170.1‘Structuraldesign
actionsPart1:Permanent,imposedandotheractions’.
Forstairs,handrailsandbalustrades,theBCAisprimarilyconcernedwiththesafetyofbuildingusers
andoccupants.Designandconstructionmustthereforetakeintoconsiderationboththestrengthand
durabilityofmaterialsandcomponentsaswellasthe‘geometric’constraintsprescribedbytheBCA.
ThefollowingprovidesabriefsummaryofsomeoftheBCArequirements.Forfulldetailsrefertothe
BCA.
2.2 Stairs
AsummaryoftherequirementsoftheBCAforstraightflightsofstairsisgivenbelow.
Eachflightmusthavenotmorethan18norlessthan2risers.
• Thenominaldimensionofgoingsandrisersofastairmustbeconstantthroughouteachstairflight.
• Theriseropeningmustnotallowa125mmspheretopassthroughbetweenthetreads.
• Thegoing(G),riser(R)andsloperelationshipquantity(2R+G)mustbeinaccordancewith
Table2.1.
• Landingsmustbenotlessthan750mmlongandwherethisinvolvesachangeindirection,the
lengthismeasured500mmfromtheinsideedgeofthelanding(AppendixFigureA1).
• Landingsmustbeprovidedwherethesillofathresholdofadoorwayopensontoastairthatprovides
achangeinfloorlevelorfloortogroundlevelgreaterthan3risersor570mm(Figure2.2).

The BCA does not
prescribe a minimum
width for stairs.


Note:TheBCAdoesnotprescribeaminimumwidthforstairs.
Table 2.1: Riser and going dimensions.
StairRiserandGoingDimensions(mm)
Riser(R)Going(G)
(seefollowingFigure)

SlopeRelationship
(2R+G)

StairType

Max

Min

Max

Min

Max

Min

Stairs(otherthanspiral)

190

115

355


240

700

550

Spiral

220

140

370

210

680

590

#08 • Stairs, Balustrades and Handrails Class 1 Buildings – Construction

Page 10


Figure 2.1: Landing length.

Figure 2.2: Threshold landings.


2.3 Balustrades and Handrails
Acontinuousbalustradeorotherbarriermustbeprovidedalongthesideofanyrooftowhichpublic
accessisprovided,anystairwayorramp,anyfloor,corridor,hallway,balcony,verandah,mezzanine,
accessbridgeorthelikeandalongthesideofanypathofaccesstoabuilding,ifitisnotboundedby
awall;andanylevelismorethan1mabovethesurfacebeneath(Figure2.3).
Theheightofabalustradeorotherbarriermustbenotlessthan1mabovethefloorofanyaccess
path,balcony,landing,etc,andnotbelessthan865mmabovethenosingsofthestairtreadsorthe
floorofaramp(Figure2.4).

#08 • Stairs, Balustrades and Handrails Class 1 Buildings - Construction

Page 11


Openingsinbalustrades(includingdecorativebalustrades)orotherbarriersmustbeconstructed
sothatanyopeningdoesnotpermita125mmspheretopassthroughitandforstairs,thespaceis
testedabovethenosingline(Figure2.4).
Forfloorsmorethan4mabovethesurfacebeneath,anyhorizontalelementswithinthebalustradeor
otherbarrierbetween150mmand760mmabovethefloormustnotfacilitateclimbing.

Balustrades and
handrails are
required when stairs
are not bounded by a
wall and any level is
more than 1 m above
the surface beneath.

Figure 2.3: Balustrades – when required.


Figure 2.4: Minimum handrail height.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings - Construction

Page 12


3

Materials for External Stairs
Without Riser Boards (Open Stairs)
Theconstructionofstairsisverydemandingandrequiresahighlevelofworkmanshipand
accuracy.Opentreadstairsarerecommendedforexternalusesincehousedriserswilltrap
moistureandpreventgooddrainageanddryingout.Housedtreadscanalsotrapmoisture
sopre-primingbeforeassemblyishighlyrecommended.AspertheBCArequirements,the
riseandgoingmustbeuniformthroughouttheflight,howeverforexternalstairsthebottom
risemayvaryslightly.
3.1 Timber Durability and Species
Inweather-exposed,above-groundapplicationsorwheresubjectedtoothersourcesofmoisture,
stringers,treads,risers,handrails,posts,newels,balusters,andinfillshouldbe:
(i)Warm,humidtropicalnorthernclimates:eitherAboveGroundDurabilityClass1specieswithany
sapwoodpresenttreatedtoH3(orhigher)orH3(orhigher)treatedsoftwoodsuchasSlash,Hoop
orRadiataPine.PreservativetreatmenttocomplywithAS1604.
(ii)Temperate,coolsouthernclimates:eitherAboveGroundDurabilityClass2orbetterspecies
withanysapwoodpresenttreatedtoH3(orhigher)orH3(orhigher)treatedsoftwoodsuchas
Slash,HooporRadiataPine.PreservativetreatmentshallcomplywithAS1604.Lowerdurability
speciescanalsobeutilisedalthoughcarefuldetailingofjointswithapplicationandmaintenanceof
protectivecoatings(paints,stains)and/orinstallationofprotectiveshielding(e.g.malthoid)ontop
ofexposedtimberedgesneedstobeutilised.
SuitablespeciesaregiveninTable3.1.

Note:
1. Meranti,VictorianAsh,TasmanianOakandDouglasFirarenotsuitableforweatherexposed
structuralapplications.
2. Forharshclimatestimberwithasawnupperfaceprovidesgreaterlongtermweatheringabilitythan
adressedsurface.Steptreadsexposedtotheweathershouldthereforebesawnallroundorsized
ontwoedgesandoneface(underside)only.
3. InQueensland,timberspeciesusedinstructuralapplicationsincludingstairsandbalustrades
shallcomplywith‘ConstructionsTimbersinQueensland’asreferencedbytheBuildingCodeof
Australia.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings – Construction

Page 13


Table 3.1: Suitable species.

Species

Availability

Postsinground
contact

Postsnotin
ground,stringers,
treads,landing
framingand
decking


AboveGroundDurabilityClass1
PreservativeTreatedPine
(CaribbeanHoop,
Radiata,Slash)

Allstates

4H5Treatment

4H3Treatment

MixedOpenForest
Hardwoods(Qld,NthNSW)

Qld,NSW

SeeNote1

4

Blackbutt

Qld,NSW

SeeNote1

4

Cypress


Alleasternstates

SapwoodFree

4

GumForestRed

Qld

4

4

GumGrey

Qld,NSW

4

4

GumRiverRed

Vic,NSW

SeeNote1

4


GumSpotted

Qld,NSW,Vic

SeeNote1

4

IronbarkRedorGrey

Qld,NSW,Vic

4

4

Jarrah

WA,SA,Vic

SeeNote1

4

Kwila(Merbau)

Allstates

MahoganyRed


Qld,NSW

SeeNote1

4

MahoganyWhite

Qld,NSW

4

4

MessmateGympie

Qld,NSW

4

4

Tallowwood

Qld,NSW

4

4


Turpentine

Qld,NSW

4

4

4

AboveGroundDurabilityClass2

Ensure timbers
used for external
stair construction
have the required
durability.

AshSilvertop

Vic,NSW

4

GumSouthernBlue

Vic,NSW

4


GumSydneyBlue

Vic,NSW

4

GumMountainGrey

Vic,NSW

4

Jarrah

WA,SA,Vic

Kapur

Allstates

4

Karri

WA,SA,Vic

4

MahoganySouthern


Vic,NSW

4

StringybarkBlue-Leaved

NSW

4

StringybarkYellow

Vic,NSW

4

SeeNote1

4

Notes:
1.Thesetimbersshouldonlybeusedforin-groundapplicationsiftheycanbeeasilyreplacedifdegradeoccurs.
2.InQueensland,timberspeciesusedinstructuralapplicationsincludingstairs,balustradesandhandrailsshall
complywith‘ConstructionsTimbersinQueensland’asreferencedbytheBuildingCodeofAustralia.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings - Construction

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3.2 Timber Grade
Structural members
should be free of
any major strength
reducing features.

Asstairstringers,treadsandposts,etc,arestructuralmembers,theyarerequiredtobestressgraded
andshouldbefreefromanymajorstrength-reducingfeatures.Inaddition,timberforstairconstruction
shouldalsobestraightgrainedandfreefromanyimperfectionsthatmaydetractfromdurabilityor
serviceabilityperformancerequirements.Stringers,treadsandpostsshouldbeinaccordancewiththe
followingtable.
Table 3.2: Timber grade.
Species

AustralianStandard

Grade

Hardwood

AS 2082

Structural Grade 1, Appearance grade

Softwood (Caribbean, Radiata,
Slash and imported softwood)

AS 2858

Structural Grade 1, Appearance grade


Hoop Pine

AS 2858

F8 Appearance grade

Cypress Pine

AS 2858

F7 Appearance grade

Note:Inaddition,finger-jointedtimbershallcomplywithAS5068–Timber–‘Fingerjointsinstructuralproducts’
andlaminatedtimbershallcomplywithAS1328–‘Gluedlaminatedstructuraltimber’.

3.3 Moisture Content

Allowance should
therefore be made
for shrinkage in
unseasoned stringers,
treads and any
associated newel
posts, landing bearers
and joists, etc.

Traditionally,timberusedforexternalstairconstructionisunseasoned.Dependingonlocationand
species,theamountofshrinkageoccurringinunseasonedtimberwillvary.Generally,about6%
shrinkage(6mmper100mm)shouldbeexpectedforunseasonedopenforesthardwoods.Allowance

shouldthereforebemadeforshrinkageinunseasonedstringers,treadsandanyassociatednewel
posts,landingbearersandjoists,etc,andforthegapsthatwilldevelopbetweenjointssuchas
betweenstringerhousingsandtreads.
ExternalstairtimbersexposedtotheweatherwillreachEquilibriumMoistureContent(EMC)withtheir
surroundingsafteraperiodof9-18months,dependinguponprevailingweather,sizeandtypeof
timberused.
ForcoastalAustralia,stairsthatarewellventilatedshouldreachanEMCofapproximately16%.For
stairsclosetoandoverwater,EMCswillnormallybealittlehigher(18-21%)andfordryinlandareas
considerablylower(10-12%).
Note:Ifseasonedtimberisusedforexternalstairscoastalareas,considerationmustbegiventothe
expansionofthetimberastheEMCrisesfrom12%uptoabout16%,particularlyatjoints–suchas
wheretreadsarehousedintostringers–andmaycausesplitting.
3.4 Joint Priming
Onecoatofawater-repellentpreservativeoranoil-basedprimerisrecommendedtobeappliedto
jointsandhousings,etc,priortofabrication.
3.5 Corrosion Protection of Fasteners

Except in severe
environments, hot
dipped galvanised
fasteners will afford
the necessary
protection from
corrosion.

Havingensuredthatthemaximumservicelifewillbeachievedinthetimbercomponent,itisequally
importanttomatchthiswithnails,screws,boltsandothermetalconnectorsofequivalentservicelife.
Formostsituations(uptoandincludingcloseproximitytoprotectedbays/mildmarine)inexposed
environments,hotdippedgalvanisedfastenerswillaffordthenecessaryprotectionfromcorrosion.
Theservicelifeofhotdippedgalvanisedcoatingswillbeproportionaltotheirmass/areaorthickness

ofgalvanisingandaminimumthicknessof42micronsisrecommendedforaservicelifeofaround
30years.Formoreextremecorrosiveenvironmentsorwhereotherconditionsdictatesuchasin
contactwithmoistCCA/ACQ,etc,treatedtimberorincloseproximitytoswimmingpools(within
600mmofedge),guidancecanbeobtainedfromTable3.3.

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Table 3.3: Selecting corrosive resistant fasteners.
Application/Environment

FastenerMaterial

Remarks

Chemical,industrialand
marinesurfbeachor
largebays

Grade316stainless
steel

Grade304stainlesssteelmayrequire
additionalprotectivecoatingssuchas
epoxypaints.

Splashzonecloseto
pools


Monelmetal,silicon
bronzeandbrass.Self
drillingscrewstobe
Class4finish.

Monelnailsandscrewsavailable,usually
usedforboatbuilding,areagoodoption
closetopools.Silicabronzenailsaregood
foracidicspeciessuchaswesternred
cedar.

Mildmarine,industrial
andother

Hotdippedgalvanised
ormechanicallyplated,
minimumthickness
42microns.Selfdrilling
screwstoClass3finish.

Wherehotdippedgalvanisedbolts,etc,
areincontactwithmoistCCA/ACQ,etc,
treatedtimber,additionalprotectionusing
plasticsheaths,bituminousorepoxypaints
isrequired.

3.6 Termite Protection
Physicaland/orchemicalbarriersmustbeprovidedtoprotectthestairsandtoensuretermitesdonot
bypassprotectionsystemstoadjacentstructures.Termitebarriersmustbedesignedsothattheycan

bereadilyinspectedandmaintained.

Figure 3.1: Typical termite protection methods.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings - Construction

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3.7 Slip Resistance
TheBCArequiresstairtreadstohaveaslipresistantfinishorananti-skidstripnearthenoseofthe
tread.Anumberofproprietary‘paints’and‘strips’areavailabletosatisfythisrequirement.
3.8 Sizes
ThesizesandspansforstringersandtreadsforexternalstairsshallbeinaccordancewithTable3.4
and3.5.
Table 3.4: Stair stringers (maximum stair width 1800 mm).
TimberType



Stringer–[Depth(mm)xThickness(mm)](1)



200x38

200x50

250x50


300x50

3600

3900

4500

3100

3400

3700

4300

2600

3000

3300

3600

4200

DouglasFir(NthAmerican) F11

2400


2700

3000

3400

3900

Radiata,Hoop,Slash,etc

F8

2300

2600

2900

3200

3700

H3treatedpine

F5

1600

2200


2400

2800

3400

Species/Group

Grade(2)

Messmate,SpottedGum,
Blackbutt,Kwila,etc

F27

2900

3200

VicAsh,TasOak,Jarrah

F22

2800

SpottedGum,Blackbutt,
Ironbark,Kwila,etc

F17(3)


Maximum Stringer Span

250x38
(mm)(4)

Notes:
1.ThesizeofstringersgivenintheTablearenominalsizes.Designallowanceshavebeenmadefor
dressing(depth10mmmax,thickness5mmmax).Allowancehasalsobeenmadefortrenchingstringersto
accommodatetreads(10mmmax).
2.TimbergradingshouldbeinaccordancewiththeappropriateAustralianStandardformilledproducts(i.e.AS
2792andAS4785).ThestressgradesusedfordesigninaccordancewiththeloadingrequirementsoftheBCA
areasindicatedandcanbedeterminedforAS2082andAS2858asappropriate.
3.TheF17gradeincludedintheTableisintendedforunseasonedhardwood,tobeusedforexternalstairsonly.
4.Stringerspanisthecentrelinelengthofthestringer.

Table 3.5: Stair treads (with open flights).
Stringer span is the
centre line length of
the stringer

TimberType



StairWidth[Treadspan](mm)



750


1000

1500

1800

38

48

58

34

40

50

60

28

36

42

53

65


DouglasFir(NthAmerican) F11

31

40

46

58

70

Radiata,Hoop,Slash,etc

F8

32

42

50

62

73

H3treatedpine

F5


40

46

54

70

N/A

Species/Group

Grade(2)

Messmate,SpottedGum,
Blackbutt,Kwila,etc

F27

26

32

VicAsh,TasOak,Jarrah

F22

28

SpottedGum,Kwila,

Ironbark,etc

F17(3)

1200

Minimum Thickness of Tread

(mm)(1)


Notes:
1.ThethicknessesintheTableareminimumdesignthicknessesandmaynotrepresentcommerciallyavailable
thicknesses.
2.TimbergradingshouldbeinaccordancewiththeappropriateAustralianStandardformilledproducts(ieAS
2792andAS4785).ThestressgradesusedfordesigninaccordancewiththeloadingrequirementsoftheBCA
areasindicatedandcanbedeterminedforAS2082andAS2858asappropriate.
3.TheF17gradeincludedintheTableisintendedforunseasonedhardwood,tobeusedforexternalstairsonly.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings - Construction

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4

Materials for Internal Stairs –
With and Without Riser Boards
(Open and Closed Stairs)
Interiorstaircaseworkisconsideredtobeaspecialisedsectionofcarpentryandjoinery.

Flightsareoftenpreparedinaworkshopmakingfulluseofavailablemachinesand
equipment.Interiorstairsdifferconsiderablyindesign,fromsimplestraightflights,
commonlyusedindomesticwork,tomoreelaboratestairsconstructedpurposelyasan
attractivefeatureinpublicandcommercialbuildingsandineleganthomes.
Manyinteriorstairsarebuiltfromjoineryqualitytimbercutandseasonedspeciallyforstairs.
Thespecifiedfinishisoftenclearpolish/polyurethane,etc,thereforebothmaterialand
workmanshipshouldbeoftheveryhigheststandard.
4.1 Timber Durability and Species

Hardness may need
to be considered for
uncovered treads.

Forinternaluse,timberofanydurabilityclassissuitable,howeverhardnessmayneedtobe
consideredforuncoveredtreads.
Thespecieschosenwillgenerallydeterminetheoverallcolourofthestairs.Asaguide,Table4.1
indicatestherangeofcoloursthatmaybeexpected.Thesapwoodofmanyhardwoodscanbemuch
lighterthanadjacentheartwoodandsometreads,risers,strings,etc,maycontainbothlightanddark
colours.

The selection
of a hard timber
species ensures
improved resistance
to indentation and
abrasion.

Lyctidsusceptiblesapwoodofsomehardwoodspeciese.g.SpottedGumisrequiredbysomestate
legislation,includingQueenslandandNewSouthWales,tobepreservativetreated.Sometreatments
mayimpartabrownorgreen-greytingetosapwood,whileboronpreservativeisnon-colouring.LOSP

treatmentisalsoused.InthisinstanceaH3treatmentmaybeusedinlieuofH2treatmenttoavoidthe
colourfromdyesoftenusedwithH2LOSPtreatments.
Hardnessindicatesaspeciesresistancetoindentationandabrasion.Damagetotimberstairsmay
occurduetoheavyfoottrafficandinparticular‘stiletto-heel’typeloading.Theselectionofahard
timberspeciesensuresimprovedresistancetoindentationandabrasion.Softtimberspecies,ifused
forsteptreads,canbeexpectedtoindent.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings – Construction

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Table 4.1: Species guide.
Species

Availability

Colour

Hardness

Blackbutt

Qld, NSW

golden yellow to pale brown

very hard

Brushbox


Qld, NSW

mid brown even colour

hard

Forest Red Gum

Qld, NSW

dark brown or dark red brown

very hard

Ironbark

Qld, NSW, Vic

dark brown or dark red brown

very hard

Jarrah

WA, SA, Vic

dark red brown

hard


Karri

WA, SA

rich reddish-browns to pale pinks

hard

Manna/Ribbon Gum

Vic

pale straw pinks

moderately hard

Messmate

Vic

pale yellow to pale brown

moderately hard

New England Blackbutt

Qld, NSW

straw to pale brown


very hard

Rose Gum

Qld, NSW

straw pink to light red

hard

Southern Blue Gum

NSW

pale brown with some pink

hard

Spotted Gum

Qld, NSW

brown, dark brown, light sapwood

very hard

Stringybark

Qld, NSW, Vic


yellow brown with pink tinge

hard

Sydney Blue Gum

Qld, NSW

pink to dark red

hard

Tallowwood

Qld, NSW

pale straw to light brown

hard

Tasmanian Oak

All states

pale straw to light brown, pink

moderately hard

Victorian Ash


All states

pale straw to light brown, pink

moderately hard

Kwila / Merbau

All states

dark brown

hard

Northern Box

Qld, NSW

mid brown even colour

hard

Cypress

All Eastern states

straw sapwood, dark brown heartwood

moderately hard


Hoop Pine (Araucaria)

All states

straw

soft

Radiata

All states

white to straw

soft

Australian Hardwood

Imported Hardwood

Softwoods

4.2 Timber Grade
Asstairstringers,treadsandposts,etc,arestructuralmembers,theyarerequiredtobestressgraded
andshouldbefreefromanymajorstrength-reducingfeatures.Inaddition,timberforstairconstruction
shouldalsobeseasoned,straightgrainedandfreefromanyimperfectionsthatmaydetractfrom
serviceabilityperformancerequirements.Forinternalstairs,stringers,treadsandpostsshouldbein
accordancewithAS2792,AS4785andthefollowing:
Table 4.2: Timber Grade

Type

Australian
Standard

Grade

Hardwood

AS 2082

Structural Grade 1, seasoned, Appearance grade

Softwood (Caribbean, Radiata,
Slash and imported softwood)

AS 2858

Structural Grade 1, seasoned, Appearance grade

Hoop Pine

AS 2858

F7 seasoned, Appearance grade

Cypress Pine

AS 2858


F7 seasoned, Appearance grade

Note:Inaddition,fingerjointedtimbershallcomplywithAS5068–Timber–‘Fingerjointsinstructuralproducts’
andlaminatedtimbershallcomplywithAS1328–‘Gluedlaminatedstructuraltimber’.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings - Construction

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4.3 Moisture Content
All components of
internal stairs should
be seasoned.

Unless the staircase
is in a permanently
controlled
environment, the
timber will always
move in response
to changing
environmental
conditions.

Unlessotherwisespecified,allcomponentsofinternalstairsshouldbeseasoned.Seasonedtimberis
usuallysuppliedatanaveragemoisturecontentbetween11%and13%.Whereconditionsaredrieror
inair-conditionedbuildings,moisturecontentoftimbermayvaryfrom7%to12%.Inthesesituations
thetimbermayneedtobeacclimatisedon-sitepriortofabrication.
Timberisanaturalproductthatrespondstochangesinweatherconditions.Duringperiodsofhigh

humiditytimberwillabsorbmoisturefromtheaircausingittoswellorincreaseinsize.Conversely,
duringdriertimeswhenhumiditiesarelow,timberwillshrink,reducinginsize.Unlessthestaircase
isinapermanentlycontrolledenvironment,thetimberwillalwaysmoveinresponsetochanging
environmentalconditions.Gapsbetweentreadsandhousings,treadsandriserboards,etc,can
beexpectedasthetimberaccommodatesseasonalchanges.Additionalshrinkagetothatnormally
expectedmayalsooccurwhenastaircaseisexposedtoheatsourcessuchasfireplacesorsunlight
throughlargedoorsorwindows.
Asmallamountofnoisecanbeexpectedfrommosttimberstairswhenwalkedon.Noisescanoccur
frommovementoftreadsinhousings,treadsagainstariserboardorfromtreads,risers,etc,moving
onnails.
4.4 Termite Protection
BecausetermiteprotectionofthehouseisrequiredundertheBCAinareaswheretermitesare
present,thereisnospecificrequirementforindividualtermiteprotectionofinternalstairsunlessthe
onlymethodoftermiteprotectionforthehouseistheuseoftermiteresistantmaterial.Inthiscase,
termiteresistanttimbershouldbealsochosenforthestairs.RefertoAS3660.1.
4.5 Slip Resistance
TheBCAperformancerequirementsstatethatstairtreadsornearthenosingshallbeslipresistant.A
numberofproprietary‘paints’and‘strips’areavailabletosatisfythisrequirement.
4.6 Span Tables

For feature stairs,
30 mm is suggested
as a minimum
thickness for all
treads, irrespective
of stair width.

Thesizesandspansforstringersforinternalstairswithandwithoutriserboardsshallbethesameas
forexternalstairs(Table3.4).
Note:Forinternalstringersandtreads,seasonedtimberonlyshouldbeused.

Thesizeoftreadsforinternalstairswithoutriserboardsshallbethesameasforexternalstairs(Table3.5).
Thesizeoftreadsforinternalstairsfullysupportedbyriserboardsshouldbeaminimumof19mm
thickforstairsupto1000mmwideand30mmfor1000-1800mmwide.
Note:Forfeaturestairs,30mmissuggestedasaminimumthicknessforalltreadsirrespective
ofstairwidth.
#08 • Stairs, Balustrades and Handrails Class 1 Buildings - Construction

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5

Stair Construction Procedure
Beforecommencingthemarkoutforstairs,thecalculationsforgoingandrisecanbe
determined(seeAppendixB).Fromthese,makeamargintemplateandpitchboardorsetup
asteelsquarewithclampsreadytomarkoutstrings.
5.1 Margin Template and Pitch Board
5.1.1 Pitch Board
Usingapieceofplywood,masonite(suchasplyormasonitebracing)orsimilar,markoutandcuta
pitchboardusingthegoingandrisecalculated(Figure5.1).

Figure 5.1: Pitch board.

5.1.2 Margin Template
Beforethemargintemplatecanbeprepared,thewidthofthemargin(X)mustbeknown.Themethod
offindingthemarginwidthisasfollows(Figure5.2):
i) Placethepitchboardonthestring,withthehypotenuseofthepitchboardflushwiththestring
edge.
ii) Useoff-cutpiecesoftreadandriserboardtodrawintothistrialposition,thetread,andalsoriser
andwedgesifused.

Note:Forstairswithriserboards,placetheoff-cutpieceoftreadupsidedownandalignthefrontedge
oftheriserhousingwiththeedgeofthestringasshowninFigure5.2.
iii)Drawalinejustbelowthetread(orwedgesifused)andparalleltothestringedge.
iv)ThedistanceXisthewidthrequiredforthemargintemplate.

Figure 5.2: Determination of margin line.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings – Construction

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Asuitablemargintemplatecannowbeconstructedusingoff-cutsfrommouldings(Figure5.3).

Figure 5.3: Margin template.

Note:Thismethodmaybefollowedtodeterminethewidthoftimberrequiredforstrings.
5.1.3 Steel Square
Anylargemetalsquaresuchasaroofingsquarecanbeusedasanalternativetoapitchboardand
margintemplate,butanunderstandingoftheproceedingmethodsisnecessarytobeabletosetthe
squareupcorrectly.
Usethesteelsquareandmetalstopstofindthemarginlineasper5.1.2andFigure5.4.

Figure 5.4: Using steel square to determine margin line.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings - Construction

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Resetmetalstopsonsteelsquareincorporatingmarginline(Figure5.5).

Figure 5.5: Using steel square as combined margin template and pitch board.

5.2 Marking Out Strings
A good practice
is to always mark
out the same hand
string first.

Whenmarkingoutstairstringsaroutinewillpreventmistakesandthewastingoftime.Agoodpractice
istoalwaysmarkoutthesamehandstringfirst.
Thispracticeshoulddevelopaclearerrecognitionofthecorrectpositioningofmembers.
Note:Theacceptedpracticeofmarkingrighthandorlefthandstringfirstvariesfromstatetostate
andregiontoregion.Theprocedurebelowisbaseduponmarkingthelefthandstringfirst.
Step1
Thestringhandingisdeterminedbylookinguptheflightorattheflightfromthebottom.Thestringto
theleftistheleft-handstring.Thetwostringsinoneflightareapair;oneleftandoneright-handstring.
Step2
Placestringsinpairsonsawtoolsandmarkinsidefaceandtopedges–considertheeffectofany
springorbow.Forshortflightswithonestepbolt,placethehollowofthebowinandforlongerflights
withtwostepboltsplacethehollowofthebowout.Stringedgesshouldberoundsup(springup)
(Figure5.6).

Figure 5.6: Pairing strings.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings - Construction

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Step3
Havingpairedthestringsbyfaceandedgemarkingthem,commencemarkingouttheleft-hand
string.Drawthemarginlinewiththemargintemplate,thenusingthepitchboard,startatthebottomof
theflightandmarkthepositionofthefloor,thefirstriseandgoing(Figure5.6).
Beforecontinuingtomarkthestring,apairofwingdividerssettodistance‘H’inFigure5.6shouldbe
usedtomarkalongthemarginline,thenumberofremainingstepsintheflight.Thisactionwillserveto
equalisesuccessivemarkingwiththepitchboardandavoidpossiblelossorgain.
Step4
Aftercompletingthemarkingofthefirststring,placebothstringstogetherasapairandsquarethe
pointsonthemarginlineacrossfromonetotheother.Thismethodwillpreventlengthdifferences
betweenthetwostrings(Figure5.7andFigure5.8).

Figure 5.7: Marking out left string.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings - Construction

Page 24


Figure 5.8: Marking out right string.

Gauge depth =
tread thickness
minus housing depth.

Step5
Whensatisfiedthattheinitialmarking,asinFigure5.8,iscorrect,proceedtocompletethemarking
forthehousings.Numbereachtreadandriser.Selecttreadsandrisers(ifused)innumericalorder
andscribethicknessandshapeontostrings.Usingagauge,markthehousingdepth(15mm)onto

thebackedgeofthestring.Alwaysgaugefromtheoutsideofthetread.Thiswillaccountforany
differencesinthicknessofthetreadparticularlywhenusingunseasonedroughsawntimber.
Note:Gaugedepth=treadthicknessminushousingdepth(Figure5.9).

Figure 5.9: String marked out for housings.

#08 • Stairs, Balustrades and Handrails Class 1 Buildings - Construction

Page 25