Building in bushfire-prone areas

The Building Act 2011 and Building Regulations 2012 adopt the BCA as the primary applicable building standard for all new buildings and incidental structures in Western Australia. The BCA also applies to new building work to existing buildings.  The BCA sets out the minimum technical requirements for design and construction and includes specific bush fire requirements for certain residential buildings in bush fire prone areas.

Building work also includes the installation of roof-mounted evaporative coolers on residential buildings located in designated bush fire prone areas (see Question 20 for further information).

If you are planning to undertake building work in a designated bush fire prone area, for example constructing a new dwelling or an extension to an existing building, then you may be required to comply with the bush fire construction requirements of the BCA.

Building work also includes the installation of roof-mounted evaporative coolers on residential buildings located in designated bush fire prone areas (see Question 20 for further information).

The BCA bush fire construction requirements apply to the following classes of residential buildings located in designated bush fire prone areas:

Class 1a — A single dwelling being a detached house, or row houses, duplexes, town houses, terrace houses or villa units where attached dwellings are separated by a fire resisting wall.

Class 1b — Includes the following:

• boarding houses, guest houses, hostels or the like in which not more than 12 people would ordinarily be resident and with a total area of all floors not exceeding 300m²; or
• four or more single dwellings located on one allotment and used for short term holiday accommodation.

Class 2 — Dwellings, such as apartments and flats in a building containing two or more units.

Class 3 — A residential building which is a common place of long term or transient living for a number of unrelated persons, including:

• a boarding or lodging house, guest house, hostel, or backpackers accommodation;
• a residential part of a hotel or motel;
• a residential part of a school;
• accommodation for the aged, children or people with disabilities;
• a residential part of a health-care building which accommodates members of staff; or
• a residential part of a detention centre.

Class 10a buildings and decks associated with Class 1a, Class 1b, Class 2 or Class 3 buildings.

Class 10a buildings include non-habitable buildings such as garages, carport, shed, or the like.

The Map of Bush Fire Prone Areas (the Map) identifies land that has been designated as a bush fire prone area by the Fire and Emergency Services (FES) Commissioner. You can view the Map on the Department of Fire and Emergency Services website. 

A building located wholly or partially within a bush fire prone area (i.e. an area coloured pink on the Map) may be required to comply with additional bushfire building requirements.

A building located entirely outside of a bush fire prone area (i.e. located in a non-pink area), regardless of whether any other portion of the same lot is within a bush fire prone area, is not required to comply with additional bushfire building requirements.

Under the Building Regulations 2012 there is a four-month transition period before the bush fire construction requirements of the BCA are triggered for certain residential buildings in new designated bush fire prone areas. This four-month transition period starts from the date that an order designating a new area as bush fire prone by the FES Commissioner comes into operation.

For example, if the land was first designated on 8 December 2015, then compliance with the bush fire construction requirements was required on and from the 8 April 2016.

Once the four-month transition period ends, applications for building approval for certain residential buildings in those areas, will need to address compliance with the bush fire construction requirements of the BCA.

Please see Industry Bulletin 58 - Building Amendment Regulations (No. 3) 2015 and Industry Bulletin 59 - Launch of designated bush fire prone area reforms for further information.

Alterations and additions

The bush fire building requirements do not apply to certain building work which relates to some existing buildings.  The exclusions apply to building work that is:

• the renovation, alteration, extension, improvement or repair of a “relevant building” if:-
  • the estimated value of the building work is less than $20,000; or
  • it does not increase the risk of ignition from bush fire attack for the existing building.

A “relevant building” is an existing building that:

1. was not required to comply with bushfire standards when it was constructed;
2. was not required to comply with bushfire standards as part of a change of classification;
3. if the works were unauthorised, was not required to comply with bushfire standards as part of an approval for unauthorised building work;
4. was not required to comply with bushfire standards if it was a relocated building.

Class 10a and decks

New or relocated Class 10a or decks do not need to comply with the bushfire construction requirements if they are associated with a relevant building as outlined above.

Newly designated bushfire prone areas

Building work does not need to comply with the bushfire construction requirements in areas that have been newly designated as a bushfire prone area by the Department of Fire and Emergency Services map for less than four months before the date a building permit application is made.

If you are not sure if your building work needs to comply with the BCA bush fire construction requirements, you should discuss the project with either the relevant permit authority or a private building surveyor.

Building legislation in Western Australia adopts the Building Code of Australia, being Volumes One and Two of the National Construction Code (NCC), as the applicable building standard.

The NCC is a performance based document. The NCC Performance Requirements can be met using a Performance Solution, a Deemed-to-Satisfy (DTS) solution, or a combination of both.

Compliance with bush fire BCA Performance Requirements G5.1 (in BCA Volume One) and P2.7.5 (in BCA Volume 2) for certain residential buildings in designated bush fire prone areas can be demonstrated by Deemed-to-Satisfy Solutions; Performance Solutions or a combination of both.

Deemed-to-Satisfy Solutions are prescriptive. They tell you what, when and how to do something. They include materials, components, design factors and construction methods that, if used, are deemed to meet the Performance Requirements, hence the term “Deemed-to-Satisfy”.

Performance Solutions are unique for each individual situation. These solutions are often flexible in achieving the outcomes and encouraging innovative design and technology use. A Performance Solution directly addresses the Performance Requirements by using one or more of the Assessment Methods available in the NCC.

For Class 1a or Class 1b buildings and associated Class 10a buildings or decks, DTS Solutions include compliance with:

• AS 3959; or
• National Association of Steel Housing (NASH) Standard – Steel Framed Construction in Bush fire Areas (2014, incorporating Amendment A).

For Class 2 or Class 3 buildings and associated Class 10a buildings or decks, the DTS Solution is compliance with AS 3959.

AS 3959 can be purchased from Standards Australia website. 

The BCA has adopted AS 3959 as one way of meeting the bush fire Performance Requirements of the BCA when undertaking building work in a designated bush fire prone area.

AS 3959 contains two methods for determining the potential intensity of bushfire attack on a building, also known as a Bushfire Attack Levels (BAL). These methods are Method 1 (simplified) BAL assessment and Method 2 (detailed).

The BAL for the specific building will determine the level of bush fire resistant construction that the building must include.  There are six BAL ratings with corresponding construction requirements:

• BAL - LOW   (Information available in AS3959 Section 4)
• BAL - 12.5    (Detailed construction information available in AS3959 Section 3 and 5)
• BAL - 19       (Detailed construction information available in AS3959 Section 3 and 6)
• BAL - 29       (Detailed construction information available in AS3959 Section 3 and 7)
• BAL - 40       (Detailed construction information available in AS3959 Section 3 and 8)
• BAL - FZ       (Detailed construction information available in AS3959 Section 3 and 9)

The standard considers such elements as:

• General matters
• Construction requirements for specific structures
• External moldings
• Higher levels of construction
• Reduction in construction requirements due to shielding
• Vents weepholes and gaps
• Bush fire shutters
• Testing to AS 1530.8.1
• Glazing
• Sarking
• Timber log walls
• Subfloor supports
• Floors
• External walls
• External glazed elements and assemblies and external doors
• Roofs, including verandah and attached carport roofs, penetrations, roof lights, eaves, fascia’s, gables, gutters and downpipes
• Verandahs, decks, steps, ramps and landings
• Roof mounted evaporative coolers
• Water and gas supply pipes
• Flame Zone testing to AS 1530.8.2

Any associated structures such as garages, carports, decks or verandas that are attached or adjacent to a building required to comply with the standard also need to comply. This could mean that the structure will need to meet the same construction requirements as the house, or be adequately separated from the house either by the nature of its construction or by its distance from the house.

While AS 3959 improves the performance of buildings subject to bush fire attack, there is no guarantee however, that a building will survive a bush fire on every occasion. This is due to the unpredictable behaviour of fire and extreme weather.

A framework for the accreditation and training of Bushfire Attack Level (BAL) Assessors and bush fire planning consultants has been developed by the State Government. The framework provides guidance for organisations that are seeking to become accrediting bodies and provide accreditation schemes for bush fire planning consultants in Western Australia.

To find out more about the accreditation framework, including accrediting organisations recognised by the State Government, and details of training courses, please visit the Department of Planning website.

AS 3959 requires the building to be assessed to determine the “Bushfire Attack Level” (BAL). The standard defines (BAL) as:

A means of measuring the severity of a building’s potential exposure to ember attack, radiant heat and direct flame contact, using increments of radiant heat expressed in kilowatts per metre squared, and the basis for establishing the requirements for construction to improve protection of building elements from attack by bushfire.

The determination of a BAL in accordance with AS 3959 is a site specific assessment that takes into consideration a number of factors, including the slope of the land, types of surrounding vegetation and its proximity to any other buildings or structures on the site. At the end of the assessment the building will be assigned one of six BALs. The assigned BAL determines the level of bush fire resistant construction required for the building.

The BALs are as follows:

• BAL-LOW - very low risk (bush fire resistant construction is not required)
• BAL-12.5 - low risk
• BAL-19 - moderate risk
• BAL-29 - high risk
• BAL-40 - very high risk
• BAL-FZ - extreme risk (Flame Zone)

The BCA requires an assessment of the potential intensity of bush fire attack for certain classes of residential buildings located in designated bush fire prone areas. AS 3959 provides methods for measuring the severity of the building’s potential exposure to ember attack, radiant heat and direct flame contact.

The determination of a building’s Bushfire Attack Level (BAL) is a site specific assessment that takes into consideration a number of factors including the slope of the land, the types of surrounding vegetation and the distance of the building to that vegetation. At the end of the assessment the building will be assigned one of six BALs. The assigned BAL determines the level of bush fire resistant construction required for the building.

The BALs are as follows:

• BAL-LOW - very low risk (bush fire resistant construction is not required)
• BAL-12.5 - low risk
• BAL-19 - moderate risk
• BAL-29 - high risk
• BAL-40 - very high risk
• BAL-FZ - extreme risk (Flame Zone)

In the first instance queries about the application of the BCA bush fire construction requirements should be referred to the building surveyor who will be signing, or has signed, the relevant Certificate of Design Compliance for the building.

For uncertified building permit applications, this may be the building surveyor at the permit authority. For certified building permit applications this may be either the building surveyor at the permit authority (if the permit authority provides that service) or a building surveying contractor (private building surveyor).

Your local government will have building surveyors or access to building surveyors; alternatively, you can engage the services of a building surveying contractor (also known as a private building surveyor). A list of registered building surveying contractors can be found via the register or online search.

The Fire Protection Association Australia has been recognised by the State Government as an accrediting body for Level 1 Bushfire Attack Level (BAL) Assessors, and Level 2 and Level 3 Bushfire Planning Practitioners.  The FPAA provides a list of accredited practitioners for Western Australia on its website.

As part of the building approval process, a registered building surveyor is required to sign a Certificate of Design Compliance (BA 3 Form) stating that if the building is completed in accordance with the plans and specifications it will comply with the applicable building standards, being the BCA.

This will include checking compliance with the BCA bush fire construction requirements for Class 1a, Class 1b, Class 2 or Class 3 buildings and associated Class 10a buildings or decks located in designated bush fire prone areas.

Generally, the person who is named as builder on the building permit is responsible for ensuring that:

• the building or incidental structure to which the permit applies is completed in accordance with the plans and specifications that are specified in the applicable Certificate of Design Compliance;
• the building work otherwise complies with the building permit including each condition that applies to the permit; and
• on completion of the building or incidental structure to which the building permit applies, that the building or incidental structure complies with each applicable building standard (being the BCA).

For building work that can lawfully be done without a building permit then the owner is responsible for ensuring that on completion of the building or incidental structure, that the building or incidental structure complies with each applicable building standard (being the BCA). The local government and/or permit authority has powers to enforce these requirements.

There may be some instances where an area has been designated as bush fire prone after your original home was built. So if you intend to rebuild or upgrade your home, then the new work may need to comply with the bush fire requirements of the current BCA. Even if your building work is not in a designated bush fire prone area, you should make every attempt to increase the resistance of your home to bush fires by constructing to the same requirements. A building surveyor will be able to advise you of any bush fire requirements that may apply if you are looking to upgrade, repair or rebuild your home after it has been damaged or destroyed by a bush fire.

The process for approval to upgrade, repair or rebuild will be similar to applying for building approval for a new house. After a bush fire event, many local governments will have procedures in place to ensure that applications are quickly dealt with to ensure a smooth and speedy transition of your application.

Contact your local government to find out what planning and building approvals you may require.

Building standards and regulations are generally not retrospective.

If you purchase or already own an existing house in an area that has been designated a bush fire prone area after the house was constructed, there may not be a regulatory requirement to upgrade.

However, if you are thinking about extending or carrying out extensive renovations to the existing house, the concessions highlighted in Question 5 above, may apply.

You should seek advice from your local government; qualified building surveyor or other appropriately qualified practitioner.

The installation of a roof-mounted evaporative cooler in a designated bush fire prone area is captured under the State’s building laws and must therefore comply with the performance requirements of the BCA.  This generally requires compliance with AS 3959.

Proposed roof-mounted evaporative coolers should be discussed in detail with the building surveyor and builder at the outset of planning for the project. Or if the work is exempt from a building permit, you need to discuss with the retailer or manufacturer how compliance with AS 3959 can be achieved.

If you are considering installing a roof-mounted evaporative cooler in a designated bush fire prone area you need to have your property assessed for its level of bush fire risk as this will determine the appropriate level of protection that your evaporative cooler will require.  See Question 15 'Who determines if my proposed building complies with the BCA bush fire requirements?'.

For full requirements refer to the publication Roof-mounted evaporative coolers.

Proposed skylights should be discussed in detail with the building surveyor and builder at the outset of planning for the project, or if the work is exempt from a building permit, you need to discuss with the retailer or manufacturer how compliance with AS 3959 can be achieved.

Proposed timber fixtures such as decking, stairs, windows, screens and the like should be discussed in detail with the building surveyor and builder at the outset of planning for the project.  If the work is exempt from a building permit, you need to discuss  with the retailer or manufacturer how compliance with AS 3959 can be achieved

See Section 3 of AS 3959.
Proposed garages, carports, verandas or similar structures should be discussed in detail with the building surveyor and builder at the outset of planning for the project, or if the work is exempt from a building permit, you need to discuss with the retailer or manufacturer how compliance with AS 3959 can be achieved.