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Mid-rise Timber Buildings Proposal for Change
Colin MacKenzie Technical Consultant
FWPA programs
Mid-rise Timber Buildings
Background • New engineered timber products and building
systems are now being used. • FWPA and industry assisting with the development
of new market opportunities for innovative timber building systems – commercial buildings.
• FWPA and industry understand the need to work collaboratively with key stakeholders to ensure a consistent level safety (structural, fire, durability) across all building materials.
• Growing demand from specifiers and designers to use these innovative, sustainable timber products/systems.
Objective • To provide a deemed-to-satisfy option for mid-rise
timber buildings that: – Enhances life safety and property protection
compared to current deemed-to-satisfy provisions.
– Is economically viable. – Facilitates consistent approaches to mid-rise
timber buildings. – Facilitates Sustainable Construction practices. – Is compatible with existing BCA approaches. – Achieves broad support from relevant
stakeholders.
Maximum DTS Timber Storey Height by Building Classification (BCA 2013)
Rise in storey
Type of Construction
Class 2 Class 3 Class 5 Class 6 Class 9a Class 9b
Apartments
Hotels Office Shops Healthcare
Schools & public buildings
4 or more
A A A A A A
3 A A B B A A
2 B B C C B B
1 C C C C C C
Maximum Timber Storey Height by Building Classification (BCA 2014)
Rise in storey
Type of Construction
Class 2 Class 3 Class 5 Class 6 Class 9a Class 9b
Apartments
Hotels Office Shops Healthcare
Schools & public buildings
4 or more
A A A A A A
3 A A B B A A
2 B B C C B B
1 C C C C C C
How does Australia compare to the rest of world?
Source: Timber Developments Association - NSW
How does Australia compare to the rest of world?
0
5
10
15
20
25
Hungar
y
Portu
gal
Poland
Switzer
land
Slovakia
Finlan
d
Austra
liaJa
pan
Romania
Czech
Rep
Canada
Austri
a
Denmar
kIta
lyUSA
Germ
any
UK
Slovenia
Franc
e
Icela
nd
Belgium
Greec
e
Irelan
d
Nether
lands
New Zea
land
Norway
Spain
Sweden
Nu
mb
er o
f S
tore
ys
No Sprinklers With Sprinklers
Source: Timber Developments Association - NSW
Protected Timber Exposed timber
Fire Protection – Two Methods
Proposal For Change Alternative Solution
Calculations by AS 1720.4 • Structural Only
Calculations by AS 1720.4
Fire Protection
• Fire protection provided by increased thickness to timber elements.
Char for FRL 90/90/90
2 minutes
Steel framed test Timber framed test
30 minutes
Timber framed test Steel framed test
Results – Time to Failure Non-combustible frames – 66 mins Timber – 114 mins
0
50
100
150
200
250
300
350
400
450
500
0 10 20 30 40 50 60 70 80 90
Control Test Timber Framed Test
Average temperature of protected steel column thermocouples
Time (minutes)
Ave
rag
e T
emp
erat
ure
(oC
)
Timber Construction Systems
Figure 1 Floor / Wall Junction Cavity Barrier Figure 2 Floor / External Wall Cavity Barrier
Figure 3 Wall / External Call Timber Cavity Barrier
Figure 3 Wall / External Call Mineral Wool Cavity Barrier
Lightweight Construction
Overseas
Vancouver Canada
Portland Oregon 5 stories over 1 storey concrete
Skellefteå – Sweden 7 stories
The Green – Parkville, Victoria
Massive Systems
Cross Laminated Timber • Multiple layers of laminated timber cross
at each laminate i.e. “Jumbo plywood”
Forté – Docklands, Victoria
Project: Forte Builders: Lend Lease Location: Melbourne, Vic
807 Bourke St Victoria Harbour 10 storeys 23 apartments 4 townhouses
Post-tensioned timber frames
Post-tensioned timber frames
Post-tensioned timber frames
How high can we go?
How high can we go? Timber Tower Research Project • 42 Storey • “Concrete Jointed
Timber Frame” • Carbon footprint
reduced by 60-75%.
WoodSolutions™: Design Guides • Available free by registering at:
www.woodsolutions.com.au
• The following guides are related to fire engineering and developing Alternative Solutions.
WoodSolutions™: Design Guides
Fires During Construction
• Only addressed to a limited extent in BCA
• More detailed approach considering broader range of issues required under WHS legislation
• Guide published June 2014 – being used by some contractors
Mid-rise Timber Buildings
• New Technical Guide detailing the DTS requirements for lightweight and massive systems
• Guide to be published by end of 2015
XX
Mid-rise Timber Buildings
• New training package for use by registered training providers detailing the DTS requirements for lightweight and massive systems
• Training package to be completed by end of 2015 Training Package
Mid-rise Timber Buildings
Robust Design
• Only addressed to a limited extent in the BCA and design standards
• A generic guide being drafted to assist engineers across all structural materials
• Guide to be published by end of 2015
YY
Robust Design of Mid-rise Buildings
Stakeholder Support FWPA has: • engaged with stakeholders (e.g. AFAC,
FPAA, SFS, fire protective product manufacturers) to inform and explain the Proposal For Change (PFC).
• undertaken a detailed and rigorous fire engineering analysis of the proposed DTS solutions; and
• submitted the PFC (2 February 2015).
Proposal for Change
Overview of Proposal for Change • FWPA has submitted a Proposal for Change (PFC) to
the Building Code of Australia (BCA) for the use of timber construction systems for Class 2 (apartments), Class 3 (hotels) and Class 5 (offices) buildings up to 25 metres in effective height (approximately 8 storeys).
• The proposed solutions will cover both ‘timber construction’ and ‘massive timber’ systems and will consist of the use of appropriate layers of fire-grade plasterboard and sprinklers.
• PFC accepted by ABCB for inclusion in draft BCA 2016
The proposal: • Building effective height of not more than 25m. • Protected by automatic fire sprinklers complying with
Specification E1.5 of the BCA. • Fire-Protected Timber used in applications where the
BCA DTS requires the element to be of non-combustible construction or concrete or masonry.
• Cavity barriers specified for timber framed construction to address risk of fire spread via cavities.
• No reductions in FRLs proposed despite provision of automatic fire sprinklers.
Overview of Proposal for Change
Fire-Protected Timber General Timber (High level of protection to timber) • FRL lightweight timber-framed
construction e.g. 90, 120, 140 x 45mm
• Additional precautions to reduce risk of fire spread to cavities e.g. Sprinkler system plus 2 x 13mm
fire-grade plasterboard for walls, 2 x 16mm fire-grade plasterboard for ceilings
• Additional precautions to reduce risk if fire enters or starts in cavity
e.g. cavity barriers
Fire-grade plasterboard
Timber framing
Fire-Protected Timber Massive Timber (Lower level of protection to timber) • Minimum 75mm thickness of massive
timber element, with required FRL, with no concealed spaces between plasterboard coverings and timber
e.g. CLT, Glulam, LVL • Precautions to reduce risk of timber
ignition e.g. Sprinkler system plus 1 x 16mm
fire-grade plasterboard for walls, 1 x 16mm fire-grade plasterboard for ceilings
• High inherent fire resistance of massive timber
• Comparable to minimum definition in US for heavy timber
Fire -grade plasterboard
Massive timber
Main components of Strategy • Prevent Fully Developed Fires occurring – fire
sprinklers • Reduce risk of timber structural members becoming
involved in the low probability event of failure of fire sprinklers – fire protective coverings
• If timber members involved in fire minimise impact – Massive timber – high inherent fire resistance – General timber – cavity insulation to be non-
combustible – All Cavities and concealed spaces
• provision of cavity barriers, • larger cavities provided with sprinkler coverage • robust structural design
Acknowledgements
• FWPA • TDA • Hyne • Tillings
• Available for free by registering at:
www.woodsolutions.com.au
WoodSolutions™: Design Guides
