Appendix F - Bushfire Hazard Assessment and Managment Report

Bushfire Report




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AS 3959:2018 116

APPENDIX F
BUSHFIRE-RESISTING TIMBER

(Normative)

Fl GENERAL

Bushfire-resisting timber is timber that is in solid, laminated or reconstituted form and has
been tested and is deemed to be acceptable to withstand exposure up to a BAL—29
condition.

Timber may be ‘bushfire-resisting’ by means of one or more of—
(a) the inherent properties of the material itself;
(b) being impregnated with fire-retardant chemicals; or

(c) the application of fire-retardant coatings or substrates.

F2 TESTING
The following applies:

(a) To satisfy the requirements for bushfire-resisting timber, timber shall be tested in
accordance with AS/NZS 3837 and shall meet the following criteria:

(i) | The maximum heat release rate shall be not greater than 100 kW/m’.

(ii) The average heat release rate for 10 minutes following ignition shall be not
greater than 60 kW/m? when the material is exposed to an irradiance level of
25 kW/m".

(b) Where the timber has been altered by chemicals, the test samples shall be subjected to
the regime of accelerated weathering described in Paragraph F3 except that where the
timber is protected from the weather, as described in the AS 1684 series (for example,
cladding protected by a veranda), accelerated weathering of the test samples is not
required before being tested to AS/NZS 3837.

External timbers are deemed to be protected if they are covered by a roof projection
(or similar) at 30 degrees or greater to the vertical and they are well detailed and
maintained (painted or stained and kept well ventilated).
NOTE: The purpose of testing is to assess timber performance rather than to simulate a bushfire.
The irradiance set for the test is not to be considered to be correlated to the BAL.

 

F3) ACCELERATED WEATHERING

Where accelerated weathering is required before testing to AS/NZS 3837, external fire-
retardant-coated substrates shall be subjected to the ASTM D2898 Method B weathering
regime, with the water flow rate modified to be the same as that within ASTM D2898
Method A.
NOTE: Accelerated weathering does not account for mechanical wear and tear within trafficable
areas and care should be exercised when using coating materials.

F4 BUSHFIRE-RESISTING SPECIES

The species listed in Table Fl have been tested and have met the requirements of
Paragraph F2.

 

 

 

 

© Standards Australia www.standards.org.au
117 AS 3959:2018
TABLE Fi
BUSHFIRE-RESISTANT SPECIES

Standard trade name Botanical name
Ash, silvertop Eucalyptus sieberi
Blackbutt Eucalyptus pilularis
Gum, ted, river Eucalyptus camaldulensis
Gum, spotted Corymbia maculata
Ironbark, red Eucalyptus sideroxylon
Kwila (Merbau) Inisia bijuga
Turpentine Syncarpia glomulifera

 

 

 

 

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