Standards Australia · Published 2018 · Active
Did you know new buildings in bushfire-prone areas are required to be designed and constructed according to AS 3959 2018 requirements? The AS 3959 Standard is Australia’s primary framework that lists important material and building specifications based on the assessed Bushfire Attack Level (BAL) rating of the site. These requirements cover building elements such as roofing, gutters, external walls, windows, doors, subfloors, and decks.
Following this Standard assures building compliance in bushfire-prone areas and the construction of bushfire-ready buildings. As a result, the AS 3959:2018 Standard helps protect both lives and property, reduce fire spread, and improve building resilience. It is an essential framework for building designers, architects, structural engineers, building surveyors, developers, and manufacturers to help uphold BAL compliance.
📖 What Is AS 3959:2018?
✦ KEY TAKEAWAYS
- ✓ Sets construction requirements for buildings in bushfire-prone areas.
- ✓ Issued in 2018 and based on the assessed Bushfire Attack Level (BAL).
- ✓ Referenced by the NCC and compulsory across all Australian states.
The AS 3959:2018, titled ‘Construction of Buildings in Bushfire-Prone Areas’, was issued in 2018 due to the growing risk of bushfires in Australia. It is Australia’s technical framework that outlines how new buildings and major renovations should be designed and constructed in bushfire-prone areas to improve their resistance to heat, flames, and ember attacks. It sets a framework for minimum construction requirements for new buildings based on the assessed BAL of the site. As a result, buildings will be able to more effectively withstand bushfire attacks, protecting both occupants and the building.
AS 3959 is referenced by the National Construction Code (NCC) and state planning legislation, which means its application is compulsory in bushfire-prone areas across Australia.
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📖 Bushfire Attack Level (BAL) Ratings Explained
✦ KEY TAKEAWAYS
- ✓ Six BAL categories from BAL-LOW (lowest risk) to BAL-FZ (extreme).
- ✓ Ratings based on FDI, slope, vegetation type and distance.
- ✓ Higher BAL means stricter material and construction requirements.
The AS 3959:2018 Standard utilises a structured module to determine Bushfire Attack Level (BAL) ratings based on the fire danger index (FDI), slope of the land, vegetation type, and distance from vegetation. For example, fire climbs, so if your property is located uphill from vegetation, the rating will increase. The closer your property sits to vegetation, the higher the rating will be. But the type of vegetation also matters as forest burns more quickly than grassland.
The BAL rating estimates a building’s potential risk from ember attack, radiant heat, and direct flame contact. These risks are described in the six BAL categories, being:
BAL-LOW Very low risk
There’s very low fire risk, often found in areas with little to no nearby vegetation. Radiant heat and ember attack risk is very low, and flame contact is unlikely. There are usually no specific construction requirements for this rating. However, if your property is located in a BPA (Bushfire-Prone Area), it must be constructed to BAL-12.5.
BAL-12.5 Low risk — up to 12.5 kW/m²
There’s a low fire risk with the main risk being burning embers entering gaps like the roof, vents, and decks. Radiant heat can be up to 12.5 kW/m². Building recommendations include ember-proof screens and seals, non-combustible roofing, and bushfire-resistant timber.
BAL-19 Moderate risk — 12.5–19 kW/m²
There’s a moderate fire risk with increasing ember attacks and burning debris. Radiant heat is between 12.5 and 19 kW/m². Flame contact is possible. Windows and lightweight materials become vulnerable, requiring tougher glazing and construction materials.
BAL-29 High risk — 19–29 kW/m²
There’s a high fire risk with significant ember attack and burning debris, and increased likelihood of flame contact. Radiant heat is between 19 and 29 kW/m². From this rating, timber elements become restricted, and non-combustible materials increase.
BAL-40 Very high risk — 29–40 kW/m²
There’s a very high fire risk with extreme ember attack and likely flame contact. Radiant heat is between 29 and 40 kW/m². Buildings require highly fire-resistant construction and comprehensive ember protection.
BAL-FZ Extreme risk — over 40 kW/m² (Flame Zone)
There’s an extreme fire risk with direct exposure to flames and radiant heat over 40 kW/m². This rating requires the highest level of protection with materials and designs capable of withstanding direct flame exposure and heat.
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📖 Key Construction Requirements by BAL Rating
✦ KEY TAKEAWAYS
- ✓ Higher BAL ratings demand more specialised design and materials.
- ✓ Covers roofing, gutters, walls, windows, doors, subfloors and decks.
- ✓ BAL-FZ requires the most stringent ember and flame protection.
The minimum building requirements listed in the AS 3958 2018 Standard are based upon the site’s BAL rating. The higher the BAL rating, the more specialised the design and construction requirements become. These may impact roofing, gutters, external walls, windows, doors, subfloors, and decks.
Roofing and Gutters
In bushfire-prone areas, roofing and gutters’ primary risk includes burning embers entering roof spaces and debris in gutters igniting. At a BAL-LOW rating, standard roofing is acceptable. But as the rating increases, the AS 3959:2018 framework mandates non-combustible roof materials and gutter guards. At BAL-FZ, all roof materials must be non-combustible, openings must be sealed, and gutters must be made from metal. Throughout the BAL levels, requirements will increase from basic sealing to fully ember- and flame-resistant materials.
Windows, Glazing and Doors
The main risks for windows and doors include glass breaking from radiant heat, embers entering through gaps, and flames that directly contact openings. Lower BAL ratings may require metal mesh screens and tight-fitting seals to prevent ember intrusion. From higher BAL ratings, buildings are mandated to have toughened or fire-resistant glazing systems installed, as well as fire-rated doors.
Subfloor and Decks
Timber flooring and decks rapidly ignite, which may cause flames to spread through the house. From BAL-12.5, subfloors need to be enclosed and feature improved ember sealing. Timber decks are still allowed, but it’s essential to manage gaps and debris. At higher BAL ratings, floors and decks must be designed with non-combustible materials such as steel and concrete.
Subfloor construction requirements increase from open subfloor at lower BAL to fully enclosed, non-combustible systems at higher levels. Decks in lower BAL ratings can be constructed with standard timber, but higher levels require non-combustible materials.
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📖 Approved Materials and Bushfire-Resistant Products
✦ KEY TAKEAWAYS
- ✓ Non-combustible materials are mandatory from BAL-29 upward.
- ✓ Bushfire-resistant materials are tested for fire performance.
- ✓ Manufacturers can have products assessed for BAL compliance.
According to AS 3959-2018, properties in bushfire-prone areas can only be constructed with approved materials such as non-combustible and bushfire-resistant products.
Non-combustible products won’t ignite, burn, or contribute fuel to a fire, nor will they produce significant flames when exposed to heat. Common examples include brick, concrete, masonry, steel, aluminium, fibre cement sheeting, and terracotta. Non-combustible materials are mandated from BAL-29 and upward, and absolutely critical in BAL-40 and BAL-FZ.
Bushfire-resistant materials may be combustible or non-combustible, but have been tested to perform under bushfire conditions. It doesn’t matter what the product is made of, but how it performs in fire. Examples include toughened glass windows, dense hardwoods with predictable charring, and window systems with metal mesh screens.
Materials can be used if they meet the specification requirements for the assigned BAL rating. Product manufacturers can have products assessed for BAL compliance.
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📖 Regulatory Compliance: NCC and State Legislation
✦ KEY TAKEAWAYS
- ✓ States and territories designate bushfire-prone areas through planning schemes.
- ✓ A BAL assessment is required before any building permit is issued.
- ✓ AS 3959 is the Deemed-to-Satisfy solution under the NCC.
Each state and territory designates bushfire-prone areas through planning schemes and mandates compliance. Before any construction in a bushfire-prone area can begin, a qualified consultant will need to complete a BAL assessment. This will determine how the house must be built to be compliant with the Standard requirements. Until then, you won’t be able to obtain a building permit.
These BAL ratings and their mandatory material and design requirements are listed in the AS 3959 2018. This Standard is referenced in the NCC, Australia’s main building framework, as the Deemed-to-Satisfy solution for bushfire construction. In other words, if your construction follows the specifications set in AS 3959, it is automatically considered compliant with NCC requirements.
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📖 Closing Remarks
Stop second-guessing. Start designing and constructing buildings with enhanced bushfire resistance against burning embers, radiant heat, and flame contact.
Our AS 3959:2018 Standard offers guidance on fire-resistant materials, roof protection, BAL assessments, maintenance, and much more. Purchase your AS 3959 2018 copy today and construct buildings that comply with regulations, provide long-term durability, and protect property and occupants against bushfires.
Are you a manufacturer seeking product testing services for bushfire compliance? We can help. Contact our friendly team for more information.
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Access the full AS 3959:2018 Get the official AS 3959:2018 Standard. Buy AS 3959:2018 PDF → |
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Frequently Asked Questions (FAQs)
Common questions about AS 3959 2018
AS 3959:2018 is an Australian Standard that prescribes minimum construction requirements for new buildings and major renovations in bushfire-prone areas to improve their resistance to ember attacks, radiant heat, and flame contact. These materials and building recommendations are based on a site’s specific BAL rating.
Yes, AS 3959:2018 is mandatory in Australia when building in designated bushfire-prone areas. Referenced in the NCC and state planning legislation as a Deemed-to-Satisfy solution, the Standard is legally enforced by state regulations.
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A BAL (Bushfire Attack Level) rating is an Australian Standard that measures a site’s bushfire risk, and particularly considers the potential exposure to ember attacks, radiant heat, and direct flame contact. The rating consists of six levels (BAL-LOW to BAL-FZ) that are determined by a qualified assessor who evaluates the fire danger index, slope, vegetation, and the distance to vegetation.
The BAL-FZ (Flame Zone) rating is the most severe rating. Buildings constructed within a BAL-FZ area must use non-combustible materials (such as brick, concrete, and steel) throughout the house with maximum ember and flame protection.
Yes. In most states, renovations and extensions done in buildings located in bushfire-prone areas must follow the requirements listed in AS 3959:2018. We recommend checking state-specific planning requirements before starting the renovation or extension.