Building Controls for Bushfire Safety

Building in bushfire areas requires careful planning,
siting and design. Class 1, 2 or 3 and associated
Class 10a buildings must be designed and
constructed to reduce the risk of ignition from a
bushfire while the fire front passes.
The building requirements set out in the Building
Code of Australia (BCA) have now been amended by
the Building Regulations 2006 (the Regulations).

2. Background
Following the recent bushfires in Victoria, the
Regulations have been amended with effect from 11
March 2009 to refer to the newly published Australian
Standard, AS 3959—2009 Construction of buildings in
bushfire-prone areas (the Standard).
The amendment to the Regulations amends the
relevant Performance Requirements in the BCA to
remove reference to ‘designated bushfire-prone area’
and include Class 10a buildings associated with a
Class 1, 2 or 3 building.
As a result of the amendment all proposed Class 1, 2
or 3 buildings and associated Class 10a buildings
throughout the State are subject to the site
assessment provisions required by the Standard,
though many sites will be assessed as BAL-LOW and
will not be required to comply with additional
construction requirements.
The Standard sets out construction requirements for a
building determined according to the highest Bushfire
Attack Level (BAL) of the site.
The BALs for which specific construction requirements
are set out in the Standard are:
• BAL-12.5
• BAL-19
• BAL-29
• BAL-40
There are no additional construction requirements for
an assessment of BAL-LOW.

3. Determination of BAL
The applicant must arrange an assessment of the site
and provide the Relevant Building Surveyor (RBS)
with his or her analysis of the BAL. This can be provided by your design team, Draftspersonmodern-home-by-a-boulder-mountain or Melbourne Builder.
The BAL can be determined using either the simplified
procedure set out in Clause 2.2 (Method 1) of the
Standard, or the detailed procedure set out in
Appendix B (Method 2).
Method 1 can be used for sites that have an effective
‘downslope’ under the classified vegetation between
0º and 20º.
Method 2 can be used for sites where the effective
downslope under the classified vegetation is between
21º and 30º and the slope of the land between the site
and the classified vegetation is no more than 20º
regardless of slope type.
Method 2 should only be used to determine the BAL
by a person with appropriate expertise, such as a fire
safety engineer.
The Standard does not apply where the slope under
the classified vegetation exceeds 30º downslope and
the slope of the land between the site and the
classified vegetation is more than 20º regardless of
slope type. In these instances the site assessment and
design of the building’s construction requirements will
need to be undertaken by a suitably qualified and
experienced person such as a fire safety engineer.
When a site is beyond the scope of the Standard, a
site analysis will not result in a BAL being determined.

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