Although no product or system can guarantee a building’s survival from a fire in extreme conditions, Weather Defence can provide effective protection of residential buildings (Building Classes 1-3) in bushfire zones. Weather Defence can be used to wrap the entire building, including the walls, roof and eaves to protect the occupants and contents during a bushfire.

The bushfire application is also suitable for Class 9 buildings (education, healthcare and aged care) where the BAL does not exceed 12.5 (low risk).

Weather Defence has been assessed for use on timber and metal frames, and for both metal and tiled roofs. It can also be used on external ceilings in balconies and alfresco areas.

Other benefits include:

• Improved weathertightness, preventing smoke and dangerous gases from entering the structure.
• Along with fire protective insulation, steel profiles, sealants and other accessories, Weather Defence has been tested to AS 1530.4 and AS 1530.8.2 Methods for fire tests on building materials, components and structures and can be used up to bushfire flame zones (BAL-FZ).
• Prevents moisture ingress and excessive air leakage.
• Improves energy efficiency due to lower air leakage. Also allows any glasswool insulation in the cavity to perform as intended by avoiding wind washing whereby wind driven air moves into the insulation cavity reducing its thermal effectiveness.
• It has been tested to AS/NZS 4284 Testing of building facades, and can be used wherever non-combustible materials are required by the NCC.
• High vapour permeability allows vapour to pass through the external building envelope without being trapped, preventing condensation and mould growth in the façade system.
• Once installed Weather Defence can be left exposed to the weather for up to 6 months before being covered by external cladding and the roof lining.

AS 3959 and bushfire attack levels (BAL)

AS 3959 specifies the construction requirements for buildings built in bushfire-prone areas in order to improve the building’s resistance to bushfire attack including from burning embers, radiant heat and flame contact or a combination of these.

This standard has been in development since 1991, but received a major update in 2009 in response to the devastating “Black Saturday” bushfires in Victoria in the same year.

AS 3959 sets the minimum controls for ensuring dwellings are resistant to a bushfire, and categorises the construction of buildings in bushfire prone areas into different bushfire attack levels (BAL):

The primary objective of this standard is providing protection for the occupants of buildings until the fire front passes, as well as providing a measure of protection to the building itself.

Further reading

• For more information about building in bushfire prone areas, refer to our blog.
• Our whitepaper, Building in bushfire prone areas: A 2024 Update, also provides further discussion on the topic.
• Click here to find out more about the fire resistance properties of Weather Defence