Timber in Bushfire Prone Areas Print E-mail
In many parts of Australia, the construction of new buildings and additions to existing buildings will be assessed as being in a Bushfire Prone Area. The relevant Australian Standard -- AS 3959 -- provides for a range of Bushfire Attack Levels for proposed construction. Each Level is based on the assessed threat and as the assessed threat increases, so do the restrictions on the building materials that may be used. Where there are restrictions on the building materials, timber is permitted in the lower levels provided the timber species meets certain criteria.

There are 2 main criteria:
  1. For some applications, AS 3959 indicates that there are no requirements or permits the use of timber. For such applications any timber may be used (where appropriate) provided that the timber meets the requirements of all the other standards and codes that apply to the construction.

  2. For some applications, AS 3959 restricts the use of timber to a fire-retardant-treated timber. However, the Standard does provide that some timber species are capable of meeting the required parameters (for resisting fire) without having to be subjected to fire retardant treatment. Again, the timber used must meet the requirements of all the other standards and codes that apply to the construction.

The following timber species have been tested and found to meet the required parameters without having to be subjected to fire retardant treatment:
  • Blackbutt
  • Merbau
  • Red Ironbark
  • River Red Gum
  • Silvertop Ash
  • Spotted Gum
  • Turpentine
See: Suitability of Untreated Timbers for Building in Bushfire-Prone Areas (PDF, 0.1 MB)

It should be noted that AS 3959 does not replace any other standards which might set out minimum requirements for construction in a particular area but rather AS 3959 sets out  requirements which are dependent upon the degree of assessed threat of Bushfire Attack and which are additional to the requirements of those other standards.

Further Information

The external use of building materials in houses built in declared bushfire prone areas is controlled under the Building Code of Australia (BCA) Parts P2.3.4 and 3.7.4. Before the BCA requirements apply, the local authority must declare the area, in which a house is to be built, to be a bushfire prone area.

Compliance with Australian Standard AS 3959 Construction of Buildings in Bushfire Prone Areas is 'deemed to satisfy' the BCA requirements for Class 1 Buildings.

Amendments to the Standard were incorporated into the BCA in July 2001. The amended Standard includes new criteria for the performance of timber used externally. While some timber e.g. high density and in larger sizes, will meet these performance requirements, testing is needed to confirm compliance. Testing of fire retardant treated and untreated timber has commenced, including accelerated weathering which is required prior to fire testing.

Some testing has been completed, confirming that a number of non-fire retardant treated timbers comply with the performance requirements.

Testing protocols for building materials and configuration to required performance levels are available in a report on the Suitability of Untreated Timbers for Building in Bushfire-Prone Areas (PDF, 0.1 MB) from Warrington Fire Research (Aust) Pty Ltd.

Properties and Behaviour of Common Building Materials

The properties and behaviour of common building materials used for construction in bushfire prone areas are reviewed in Literature Review of Bushfire Construction Materials & Test Protocols for Performance Assessment (PDF, 0.5 MB).

The examination of the likely performance of building elements exposed to bushfire conditions will contribute to methods of mitigating the risk to life and property presented in bushfires.

Lower Blue Mountains Report

Due to the growing concerns over the destructive impact of bushfires on lives and homes, research into identification of building and construction design parameters which limit the extent of fire damage have been completed. See: Bushfire Investigations - Warrimoo, Valley Heights & Yellow Rock, Lower Blue Mountains, NSW, 2001-2 (PDF, 0.3 MB). The findings of the report can be used to provide more effective recommendations on appropriate housing designs and the use of timber for construction purposes in bushfire-prone areas.

There is a bulletin available entitled, Building in Bushfire Areas (PDF, 0.3 MB) which summarises timber product requirements for bushfire prone areas - as defined in AS3959.

Building in Bushfire Areas
(PDF, 0.3 MB)
National Timber Development Council
Bushfire Flame Zone Resistant Sheet Metal Roofs
(PDF, 0.7 MB)
Forest and Wood Products Australia
The plywood membrane solution - a roof system for BAL-FZ which complies with the requirements of AS1530 8.2 as required by AS3959-2009
Construction of Buildings in Bushfire-Prone Areas (Draft)
(PDF, 0.2 MB)
Warrington Fire Research (WFRA Project No: 20735-002)
Literature Review of Bushfire Construction Materials & Test Protocols for Performance Assessment
(PDF, 0.5 MB)
Warrington Fire Research (WFRA Project No: 20551 V1.1)
Moisture Content of Exterior Timber in Bushfire Conditions
(PDF, 0.9 MB)
David Hayward, Timber Queensland Ltd
Suitability of Untreated Timbers for Building in Bushfire-Prone Areas
(PDF, 0.1 MB)
Warrington Fire Research (WFRA Project No. 20550.2)
Timber Design and Construction in Bushfire Prone Areas Timber Design and Construction in Bushfire Prone Areas
General information on building with timber in bushfire prone areas, BCA solutions, government directories and much more.
 
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