How to protect your home against ember attack

Bushfires are a serious threat to many homes across Australia.

But what you may be surprised to learn is that the bushfire front itself is not the main threat your home is likely to face.

Research has shown that most house fires during a bushfire are not the result of direct contact with the bushfire front at all. Instead, over 85% of homes that burn down during a bushfire are victims of ember attack. So if you’re serious about protecting your home from bushfire, you need to consider measures for defending against ember attack.

Ember attack occurs when smouldering and burning debris settles on, around or in your home and sets it alight.

This burning debris can ignite external sources of fuel such as leaves in your gutters, or it can be sucked into roof cavities and other parts of your home to start internal fires.

Because ember attack poses a significant threat to homes, many of the measures in the Australian Standard for building in bushfire-prone areas (AS3959–2009) are designed to improve your home’s ability to withstand ember attack – including the use of ember guards.

According to AS3959–2009, an ember guard is “a cover inserted in or over an opening or cavity to prevent the entry of burning embers”.

Ember guards are commonly made from a metal mesh with a maximum aperture (hole size) of 2mm. Perforated sheets with the same aperture are also permissible. Blue Mountain Co’s 2mm steel gutter mesh is an example of ember guard compliant mesh.

Generally speaking, ember guards are used to cover areas around your home where there are gaps greater than 3mm. This helps to defend your home against ember attack by preventing embers from gaining entry to your home.

(For a comprehensive explanation of ember guards and their mandated uses, click here)

Although ember guards help defend your home against the threat of internal fires from ember attack, they don’t address the problem of external fires from ember attack.

Because of this, we suggest using gutter guard compliant gutter mesh to prevent the build-up of leaves – a common bushfire fuel – in your gutters.

Any non-combustible gutter mesh is compliant for use as a gutter guard in bushfire-prone areas. However, we recommend that you choose a mesh with an appropriate aperture for keeping out the leaves in your area. Generally speaking, the smaller the leaves in your area, the smaller the aperture you should choose. For added peace of mind, you may want to use an ember guard compliant gutter mesh in order to defend your gutters against embers as well as leaves.

While no measure can guarantee your home will survive ember attack, the measures discussed here should better equip your home to do so.

And although AS3959–2009 only applies to new homes in bushfire zones, it can also be used to guide bushfire proofing measures for older homes or homes in a low bushfire risk area.

To assist you in choosing gutter mesh that’s appropriate for your home and bushfire risk, we’ve developed Mesh Matcher.

Mesh Matcher is an easy-to-use tool that asks the right questions in order to recommend appropriate gutter guard and/or ember guard options for your property.

Click here to use Mesh Matcher today

Disclaimer: Every effort has been made to ensure these guidelines are consistent with AS3959–2009. However, we cannot guarantee the accuracy of any of the information on this web page. As such, we recommend that you refer to the Australian Standard yourself, or seek tailored advice from a qualified expert.

Sources:Blanchi & Leonard, Investigation of Bushfire Attack Mechanisms Resulting in House Loss in the ACT Bushfire 2003, 2005Standards Australia, Construction of Buildings in Bushfire-Prone Areas, 2009