Regulations and Standards

Building in bushfire prone areas: What the changes mean for you

All new homes built in bushfire prone areas must comply with the Australian Standard AS3959-2009 and AS3959-2009/Amdt2011 Construction of buildings in bushfire prone areas.  This Standard is primarily concerned with improving the ability of buildings in designated bushfire prone areas to better withstand attack from bushfire, giving a measure of protection to the people inside as well as to the building itself.

After the 2009 Victorian bushfires, AS3959 was updated to the current version – AS3959-2009.  The standard contains six bushfire risk categories and prescribes minimum construction requirements based on the Bushfire Attack Level (BAL) of a site.  There are six BALs which describe different risk categories, from BAL-LOW (insignificant risk) to BAL-FZ (Flame Zone – highest risk).

BAL-Ratings

The Standard exists to provide property owners with clear direction on how to increase the protection of their homes as part of good site preparation and risk management.  Anyone considering building, renovating or retrofitting their homes need to be aware of the changes relating to ember guard compliance and what level of protection their site needs according to their specific BAL rating.

AS3959-2009 was amended in 2001 when the Victorian Bushfire Commission decided that homes built in bushfire prone areas needed to increase their ability to resist an ember attack.

The amendment requires that any gaps around the house greater than 3mm need to be sealed by a mesh or perforated sheet with a maximum aperture of 2mm so that embers have less chance of settling on or inside a house and subsequently setting it on fire.  The amendment also prescribes suitable construction materials for ember guards based on the specific Bushfire Attack Levels.  For homes situated in designated bushfire prone areas, a 2mm mesh gutter guard (steel, bronze or aluminium for BAL-12.5 – BAL-29 and steel or bronze for BAL-40 and BAL-FZ) is able to be installed as an ember guard solution.  Other ember guard options include mineral wool and other non-combustible material that can fill the 3mm gap.

Standards for building in bushfire prone areas

The Standard (Australian Standard AS3959-2009 & AS3959-2009/Amdt 2011 : Construction of Buildings in Bushfire Prone Areas), exists to provide property owners with clear direction on how to increase the protection of their homes in bushfire prone areas, as part of good site preparation and risk management.

Regarding gutter protection specifically, where the previous Standard refers to a flammability index of not greater than 5, this no longer applies.

The Standard requires, for homes in BAL zones 12.5 – FZ, any gutter protection products used must be non-combustible (refer to table below for details).  The use of products that only meet the previous Standard no longer complies.  This means that if a gutter guard is installed, regardless of whether it is acting as a gutter guard or as an ember guard, it must be non-combustible.  To prove that a gutter guard is non-combustible, it needs to meet one of the following testing standards;

  • AS 1530.1 – Methods for fire tests on building materials, components and structures Part 1: Combustibility test for materials.  Products/Materials which are not applicable to AS1530.1 are ‘products which are coated, faced or laminated’ or ‘materials that melt or shrink at the test temperatures’.
  • Building Code of Australia (BCA) – Pre-finished metal sheeting that has a combustible surface finish not exceeding 1mm thickness and where the Spread-of-Flame Index (AS1530.3:1999) of the product is not greater than 0.

The changes to AS3959-2009 have also served to highlight the importance of fitting compliant ember guards to increase the level of protection for homes in bushfire prone areas.  Anyone considering building, renovating or retrofitting their homes need to be aware of the changes relating to gutter guard and ember guard compliance and what level of protection their site needs according to their specific BAL rating to give themselves, their family and their property the best protection.

Relevant extracts from Australian Standard AS3959-2009 & AS3959-2009/Amdt 2011 : Construction of Buildings in Bushfire Prone Areas –

Gutter Guard : Relating to BAL-12.5, BAL-19, BAL-29, BAL-40, BAL-FZ respectively
Clause 5.6.7, 6.6.7, 7.6.7, 8.6.7 and 9.6.7 : Gutters and downpipes
If installed, gutter and valley leaf guards shall be non-combustible
Ember Guard : Relating to BAL-12.5, BAL-19, BAL-29 respectively
Clause 5.6.3, 6.6.3 and 7.6.3
Sheet roofs shall –
b) have any gaps greater than 3mm (such as under corrugations or ribs of sheet roofing and between roof components) sealed at the fascia or wall line and at valleys, hips and ridges by –
I. a mesh or perforated sheet with a maximum aperture of 2mm, made of corrosion resistant steel, bronze or aluminium; or
II. mineral wool; or
III. other non-combustible material; or
IV. a combination of any of items I, II or III above.
Clause 5.6.1, 6.6.1 and 7.6.1
These clauses also state the following should apply to all types of roofs and roofing systems:
A) roof tiles, roof sheets and roof covering accessories shall be non-combustible
B) roof ventilation openings, such as gable and roof vents, shall be fitted with ember guards made of non-combustible material or a mesh perforated sheet with a maximum aperture of 2mm, made of corrosion resistant steel, bronze or aluminium
Ember Guard : Relating to BAL-40 and BAL-FZ
Clause 8.6.3 and 9.6.3
Sheet roofs shall –
b) have any gaps greater than 3mm (such as corrugations or ribs of sheet roofing and between roof components) sealed at the fascia or wall line and at valleys, hips and ridges by –
I. a mesh or perforated sheet with a maximum aperture of 2mm, made of corrosion resistant steel or bronze; or
II. mineral wool; or
III. other non-combustible material; or
IV. a combination of any of items I, II or III above
Clause 8.6.1 and 9.6.1
These clauses also state the following should apply to all types of roofs and roofing systems:
C) roof tiles, roof sheets and roof covering accessories shall be non-combustible
D) roof ventilation openings, such as gable and roof vents, shall be fitted with ember guards made of non-combustible material or a mesh perforated sheet with a maximum aperture of 2mm, made of corrosion resistant steel or bronze.

 

How can I retrofit my existing home?

Sealing around roofing and roof penetrations is one of the low cost retrofitting implementations the CFA, Victorian Government & Victorian Building Commission recommend for protecting existing homes in bushfire prone areas.

These are various other measures that can be taken in the home and around the garden to protect your home.  Refer to ‘A guide to retrofit your home for better protection from a bushfire’ for more information.(CFA, Victorian Government and Victorian Building Commission 2010)