Bushfire Prone Land Mapping and How to Check Your Property

What This Requirement Covers

Designated bushfire prone land mapping identifies areas where the risk of bushfire is sufficient to trigger additional building design and construction requirements under the National Construction Code (NCC) and associated state or territory provisions. The mapping exists to ensure buildings likely to be exposed to bushfire actions are designed to reduce ignition risk, protect structural integrity during an event and, where relevant, provide a tenable environment for occupants who cannot readily evacuate. It applies to new construction, and to some alterations and additions, where the site falls within a designated bushfire prone area.

These mapping rules are administered nationally through the NCC (Part G5 in Volume One and Part H7 in Volume Two for Class 1/10 in many jurisdictions) and implemented by state and territory planning authorities. The mapping determines whether a site is in a designated bushfire prone area and therefore whether the bushfire-related provisions (including determination of a Bushfire Attack Level, BAL) and referenced standards such as AS 3959 apply to the project.

Key Requirements

1. The NCC includes a Part dealing with construction in bushfire prone areas: see NCC Volume One, Part G5 - Construction in bushfire prone areas and applicable state variations (for example TAS G5P1, VIC G5O1). These provisions apply where a site is in a designated bushfire prone area.
2. Design bushfire intensity and design criteria are expressed in terms of Bushfire Attack Levels (BAL) determined in accordance with AS 3959 - Construction of buildings in bushfire-prone areas. BAL categories include BAL-LOW, BAL-12.5, BAL-19, BAL-29, BAL-40, and BAL-FZ (Flame Zone).
3. Specific construction requirements for each BAL (materials, ember protection, glazing, eaves, external walls, roofs) are set out in AS 3959 and must be followed when the site’s BAL exceeds BAL-LOW. For example:
4. BAL-12.5 and above require attention to ember attack and radiant heat; specific glazing and external door requirements vary by BAL as per AS 3959.
5. BAL-FZ requires the most stringent construction measures, including non-combustible surfaces, reduced openings, and other limitations as specified in AS 3959.
6. Classifications and application by building class:
7. Class 1 and 10 buildings (dwellings, private garages, decks) are covered by NCC Volume Two, Part H7 where sited in designated bushfire prone areas; see H7P5 - Buildings in bushfire prone areas for Tasmania-specific wording applied to Class 1 and 10 in some jurisdictions.
8. Class 2-9 buildings are covered by NCC Volume One, Part G5; G5 provisions identify which building types must comply and when additional measures are required (for example, certain Class 9 buildings used by occupants who cannot readily evacuate).
9. When a site is in a designated bushfire prone area, a BAL assessment must be carried out in accordance with AS 3959 to determine the appropriate BAL rating for the site. The BAL assessment uses parameters such as vegetation classification, effective slope, and distance from vegetation to calculate radiant heat (kW/m2) and ember exposure.
10. Where the NCC or a state schedule requires it, the design bushfire intensity is defined by an annual exceedance probability (AEP). For example, some state provisions require design for an AEP of 1:100 years (or 1:200 years for certain building types) as expressed in state variations (for example TAS G5P1).
11. State and territory schedules in the NCC frequently modify the national provisions. For example:
12. South Australia: SA G5D5 provides how BAL is applied using the Planning and Design Code and refers to AS 3959.
13. Tasmania: TAS G5P1 and TAS H7P5 set out bushfire resistance objectives and application to different classes, and refer to AEP design criteria.
14. Common referenced Australian Standards: AS 3959 (BAL methodology and construction requirements), and cross-references to other standards for materials and structural design where relevant (e.g., AS 3700 for masonry, AS 1684 timber framing) should be used as applicable when selecting compliant construction methods and materials.

Residential vs Commercial

1. Residential (Class 1 and Class 10):
2. Covered primarily by NCC Volume Two, Part H7 when located in a designated bushfire prone area. H7 requires design and construction to reduce ignition risk from a design bushfire (see H7P5 in some jurisdictions such as Tasmania). BAL assessment in accordance with AS 3959 is used to determine construction requirements where the site is not assigned BAL-LOW.
3. Typical residential outcomes: requirements for ember-proofing, flame-resilient external finishes, limited or protected openings, and specified glazing and door standards depending on BAL. Decks and associated Class 10a buildings immediately adjacent to Class 1 dwellings are captured where listed.
4. Commercial and higher-occupancy buildings (Class 2-9):
5. Covered by NCC Volume One, Part G5. The application can be more specific: for some high-risk occupancies (e.g., health-care, early childhood, residential care - Classes 9a, 9b, 9c) the NCC imposes additional requirements to protect occupants who may not be able to evacuate easily. State variations (for example VIC G5O1) emphasise shelter and life-safety objectives as well as building protection.
6. Class 2-9 buildings may be subject to stricter AEP design levels (for certain building uses), greater structural resilience requirements and additional passive design measures. Some Class 9 uses may require a 1:200-year design event and extra building services resilience.

Exceptions and Exemptions

1. BAL-LOW: If mapping or assessment determines the site is BAL-LOW, specific AS 3959 construction measures are generally not required; however, the site remains in a designated bushfire prone area and relevant NCC provisions still apply in some jurisdictions.
2. State planning schemes can identify areas where simplified approaches apply - for example, a local planning instrument may assign BAL-Low across a large urban interface area; check the relevant planning code or council mapping.
3. Some minor works or non-habitable structures may be exempt or subject to simplified requirements depending on state/territory regulations and NCC application. For instance, Class 10b (non-habitable sheds) or minor alterations may have limited obligations; confirm with the relevant state schedule and local authority.
4. Alternative solutions: Where prescriptive AS 3959 construction is impractical, designers may adopt an alternative solution demonstrating at least an equivalent level of safety and performance in accordance with NCC procedures. This requires expert documentation and typically the involvement of a building surveyor or certifier.

State and Territory Variations

1. The NCC includes state and territory schedules (Schedules 4-12) that can modify or add requirements for bushfire prone areas. Examples:
2. Victoria: Part G5 and G5O1/G5F1 are tailored to Victorian objectives and link directly with the state Planning and Design Code and Victoria’s bushfire mapping and land use controls.
3. Tasmania: TAS G5P1 and TAS H7P5 explicitly set AEP and application to specific building classes and require consideration of design bushfire intensity and occupant tenability. Private bushfire shelters are addressed under TAS H7P6.
4. South Australia: SA G5D5 defines how BAL applies using the Planning and Design Code categories and when AS 3959 assessments are required.
5. Other states and territories have corresponding schedule clauses - always check the relevant state schedule in NCC Volume One (Schedules 4-12) and local planning/bushfire mapping portals for up-to-date local amendments.
6. Note: local council planning maps and state government bushfire mapping tools are the authoritative source to determine whether a site is in a designated bushfire prone area. State mapping portals commonly used include government or planning department websites and local council property search tools.

Practical Compliance Tips

1. Check official state bushfire mapping and council property searches first - these are the authoritative sources that show whether your site is designated bushfire prone. If the map flags the site, a BAL assessment under AS 3959 is usually the next step.
2. Commission a BAL assessment from a competent practitioner if the mapping indicates potential risk or if your site is within buffer zones where vegetation type, slope or distance are uncertain. BAL assessments use measured distances and slope - rough estimates cause errors.
3. Understand the effect of vegetation classification and slope on BAL results - small changes in measured distance to classified vegetation or the assumed slope can change the BAL from one category to another, which significantly affects required construction details.
4. Record and retain BAL documentation (site assessment, AS 3959 report) with your building submission and for future owners - certifiers and councils will commonly request the BAL report as part of approval.
5. When BAL > BAL-LOW, follow AS 3959 construction provisions exactly for the relevant BAL level or prepare a compliant alternative solution. Common mistakes include under-specified glazing, unsecured vents or unprotected eaves.
6. Check state schedule differences and planning code requirements early - some states mandate different design AEPs or require additional measures for certain building classes (for example, AEP 1:200 for some Class 9 buildings in TAS). Confirm the applicable NCC state schedule clause (e.g., TAS G5P1, SA G5D5, VIC G5O1).
7. Engage your certifier or building surveyor early for alternative solutions - if you need to deviate from AS 3959, you will need documented performance evidence and sign-off from the certifier to demonstrate an equivalent level of safety.

References cited inline where applicable: NCC Volume One - Part G5 (and state variations such as TAS G5P1, SA G5D5, VIC G5O1), NCC Volume Two - Part H7 (e.g., H7P5 for Class 1/10 in some jurisdictions), and AS 3959 - Construction of buildings in bushfire-prone areas. Always check the relevant state schedule in NCC Volume One and local planning/bushfire mapping portals for up-to-date mapping and amendments.

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