Fire Safety Requirements for Buildings Near Bushland

What This Requirement Covers

Buildings located close to bushland face increased risk from bushfire attack - including radiant heat, ember attack, and direct flame contact. The National Construction Code (NCC) contains provisions to reduce the vulnerability of buildings near classified vegetation by prescribing siting distances, construction standards, materials, and access and water-supply measures. These requirements aim to reduce ignition risk, protect structural elements, and improve occupant and firefighter safety during and after a bushfire event.

The requirements apply to designers, builders, certifiers, and owners of new and altered buildings that fall within designated bushfire prone areas or that are subject to a Bushfire Attack Level (BAL) assessment. They combine national Deemed-to-Satisfy provisions and Performance Requirements in the NCC with Australian Standards (most notably AS 3959) and state or territory schedules that modify or expand national provisions.

Key Requirements

1. Bushfire Attack Level (BAL): Determine BAL for the site in accordance with AS 3959-Construction of buildings in bushfire-prone areas. BAL categories are BAL-Low, BAL-12.5, BAL-19, BAL-29, BAL-40, BAL-FZ and dictate construction requirements and material specifications as set out in AS 3959 and referenced in the NCC (e.g., NCC Volume One, Part G5 and associated specifications).
2. Separation from classified vegetation: Where specified in NCC Volume One (Specification S43C2), buildings must be separated from classified vegetation by not less than the minimum distances in Table S43C2 or such that radiant heat flux on exposed elements does not exceed 10 kW/m2. Example table values (based on Fire Danger Index 100) include minimum distances up to 110 m for high-risk downslope conditions; full values and slope/vegetation classifications are given in Table S43C2 (NCC Volume One, Specification 43 - Bushfire protection for certain Class 9 buildings).
3. Separation between buildings: For certain buildings addressed by Specification 43, a minimum separation of 12 m between buildings is required unless both buildings are constructed to suitable bushfire-resistant standards (NCC Volume One, Specification S43C3).
4. Construction standards and materials: For buildings subject to a BAL above BAL-Low, construction must comply with the relevant sections of AS 3959, which specify materials, glazing requirements, ember and radiant heat protections, roof and wall construction, sarking, and sealing requirements. NCC references to AS 3959 appear in Part G5 Deemed-to-Satisfy provisions and state variations (e.g., NSW G5D3).
5. Applicability by building class: Deemed-to-Satisfy rules in Part G5 of NCC Volume One typically apply to Class 2, 3, 4 parts, and Class 10a buildings or decks immediately adjacent or connected to those buildings in designated bushfire prone areas (see NCC Volume One, G5D2 and state modifications such as NSW G5D2).
6. Access and water supply: For higher-risk buildings (including some Class 9 or special purpose buildings), Performance Requirements (e.g., NSW G5P2) require vehicular access to enable firefighting and emergency personnel, access to sufficient water supply on site for firefighting, and safe internal access/egress arrangements (NCC Volume One, NSW G5P2).
7. Radiant heat flux trigger: Separation or construction decisions in Specification S43C2 may be based on the criterion that radiant heat flux on exposed building elements must not exceed 10 kW/m2.
8. Reference clauses and documents:
9. NCC Volume One, Part G5 - Bushfire protection (Deemed-to-Satisfy and Performance Requirements)
10. NCC Volume One, Specification 43 - Bushfire protection for certain Class 9 buildings (S43C1-S43C3, Table S43C2)
11. NCC Volume Two - provisions for housing where bushfire prone areas and BAL are referenced (see H7D4 and SA H7D4 for jurisdictional inserts)
12. AS 3959-Construction of buildings in bushfire-prone areas (for BAL assessment and construction detailing)
13. Other referenced Australian Standards as relevant to construction detailing (for example materials standards for timber and steel: AS 1684, AS 4100, masonry AS 3700) where structural standards interact with bushfire-resistant design

Residential vs Commercial

1. Residential (Class 1 and Class 10a): The NCC Volume Two and Part H provisions (and jurisdictional inserts) address housing in bushfire-prone areas; however, many BAL-based construction controls for housing are implemented by following AS 3959 or local planning/bushfire protection documents. For standalone houses (Class 1), BAL assessment and compliance with AS 3959 construction requirements (or planning authority directions) are typically the primary controls. Decks and Class 10a structures immediately adjacent to Class 1 dwellings are treated as part of the same assessment when connected or adjacent.
2. Multi-residential and commercial (Class 2-9): For Class 2-9 buildings the NCC Volume One Part G5 and Specification 43 contain specific Deemed-to-Satisfy and Performance-based arrangements. Some Class 2, 3 and certain Class 9 buildings are covered explicitly by Deemed-to-Satisfy G5 provisions when within designated bushfire prone areas (see G5D2). Where BAL exceeds BAL-12.5 for some building types, a Performance Solution may be required (e.g., NSW G5P2 notes that buildings subject to BAL greater than BAL-12.5 may need to meet Performance Requirements by means of a Performance Solution). Class 9 special fire protection purpose buildings have bespoke separation and protection rules in Specification 43 (S43C2-S43C3). Larger commercial or higher-occupancy buildings often require a site-specific performance assessment addressing occupant tenability, firefighter access, and the combined effects of structural and fire exposure (NCC Volume One, NSW G5P2 and related clauses).

Exceptions and Exemptions

1. Where a site is designated as bushfire prone, some low-risk situations may be assigned BAL-Low without further construction upgrades; however, that does not negate ember exposure or planning controls. NCC Volume Two and state inserts define when BAL-Low applies (see H7D4 and SA H7D4).
2. Some Deemed-to-Satisfy provisions apply only up to BAL-12.5; where BAL exceeds BAL-12.5 a Performance Solution may be required and specific conditions of development consent can alter the applicable requirements (for example NSW G5D3 and related notes). In BAL-FZ (flame zone) conditions, development consent may impose special conditions or prohibit certain construction methods; AS 3959 Section 9 has restrictions and many planning authorities will impose bespoke conditions for BAL-FZ.
3. Alternative solutions: A Performance Solution under the NCC can be used instead of Deemed-to-Satisfy provisions if it can be demonstrated the Performance Requirements are met. This allows tailored design responses such as enhanced ember protection, landscaping buffers beyond minimum distances, or engineered structural resistance, provided they achieve the required safety outcomes (see NCC Volume One, Part G5 Performance Requirements).

State and Territory Variations

1. The NCC is national, but each state and territory has schedules and modifications that alter how bushfire provisions apply. Examples include:
2. New South Wales: NSW G5D2, NSW G5D3 and NSW G5P2 replace or modify national Deemed-to-Satisfy provisions; NSW requires AS 3959 compliance for many building types in designated bushfire prone areas and allows development consent conditions for BAL-FZ (NCC Volume One, NSW clauses).
3. South Australia: SA H7D4 inserts specific provisions into NCC Volume Two requiring BAL assessment for sites within certain distances of identified bushfire risk areas and defaulting to BAL-Low in some mapped general bushfire risk areas (NCC Volume Two, SA H7D4).
4. Other jurisdictions: Each state schedule (Schedules 4-12 in NCC Volume One) may contain local variations or planning requirements that affect how BAL is assessed, minimum separation distances, or what building classes are covered by Deemed-to-Satisfy rules. Always check the relevant state or territory schedule in NCC 2022 Volume One (Schedules 4-12) and local planning instruments.

Practical Compliance Tips

1. Always start with a site BAL assessment performed in accordance with AS 3959 before selecting materials or detailing - this determines which construction measures apply.
2. Check the relevant state schedule and any local planning bushfire overlays early in design - jurisdictional inserts (for example NSW G5D2/G5D3 or SA H7D4) can change applicability and thresholds.
3. Use the clear numeric triggers in the NCC and AS 3959: e.g., 10 kW/m2 radiant heat criterion, minimum separation distances from Table S43C2, and 12 m building-to-building separation where required - document these in the drawings and compliance statements.
4. For glazing and openings, follow AS 3959 glazing and ember protection details for the assessed BAL rather than relying on generic window schedules - glazing is a common weak point for ember and radiant heat ingress.
5. Provide evidence for any Performance Solution - include fire engineering assessments addressing occupant tenability, radiant heat calculations, and access/water-supply demonstrations; reference NCC Performance Requirements and the relevant state schedule.
6. Coordinate landscaping and siteworks with the building design: vegetation classification, slopes and fuel loads determine separation distances and BAL; maintain defensible space and document ongoing maintenance responsibilities.
7. Engage certifiers and Bushfire Planning Authorities early if the site is near high bushfire risk or BAL-FZ is possible. For complex or high-BAL sites, obtain written conditions of development consent where AS 3959 or the NCC allows modification through consent.

References: NCC Volume One (Part G5 and Specification 43: S43C1-S43C3; NSW G5D2/G5D3/G5P2), NCC Volume Two (H7D4 and state inserts), AS 3959-Construction of buildings in bushfire-prone areas, and related Australian Standards such as AS 1684, AS 4100 and AS 3700 where structural material specifications interact with bushfire-resistant detailing. Note: always verify against the current NCC edition and the relevant state or territory schedule for local amendments.