BAL FZ Building Guide, Section 9 – AS 3959:2018

Updated 16/07/2026

A organized summary of the BAL FZ (Bushfire Attack Level – Flame Zone) construction requirements, based on Section 9 of the AS3959:2018 Australian Standards provided in the guide:

Disclaimer: This is a reference overview and not an exhaustive list. It should be read in conjunction with the official Australian Standards AS3959:2018 (including amendments), AS1530.8.1, AS1530.8.2, and certified test reports.

General Requirements (Clause 9.1)

Any building assessed as BAL FZ must conform with general construction requirements and maintain a minimum setback distance of 10 meters from classified vegetation. If this 10m setback cannot be met, the building elements that fall short must conform with the AS1530.8.2 testing standard. Any construction system satisfying AS1530.8.2 test criteria can be used instead of the standard BAL FZ rules.

Subfloors and Floors (Clauses 9.2 & 9.3)

  • Enclosed Subfloors: No specific requirements apply to the supports and floors as long as the subfloor enclosure itself complies with BAL FZ wall requirements.
  • Unenclosed Subfloors:
    • Supports (stumps, etc.): Must have a Fire Resistance Level (FRL) of at least 30/—/— and be non-combustible, or comply with an AS1530.8.2 tested system.
    • Floors (bearers, joists, flooring): Must have an FRL of at least 30/30/30 with a non-combustible surface, or have the underside protected by a system with a 30-minute resistance to incipient fire spread, or comply with AS1530.8.2 from below.

External Walls (Clause 9.4)

Walls must be either:

  • Non-combustible (e.g., brick, concrete, rammed earth, or mud brick with a minimum thickness of 90mm).
  • A system tested from the outside conforming to AS1530.8.2.
  • A system with an FRL of 30/30/30 or —/30/30 when tested from the outside.
  • Note: Any gaps larger than 2mm must be screened with corrosion-resistant steel or bronze mesh (maximum 2mm aperture). Aluminium mesh is strictly prohibited.

Windows, Doors, and Sidelights (Clause 9.5)

Windows and doors in the Flame Zone have strict compliance paths:

  • Testing & FRL: Systems must either be fully tested to AS1530.8.2 from the outside or have an FRL of —/30/—. Non-combustible frames are standard, though some tested timber options exist.
  • Bushfire Shutters: If the window/door is not tested to AS1530.8.2, it must be completely protected by a compliant bushfire shutter (perforations are not allowed over doors).
  • Screens: All openable windows require ember/insect screens. Screens must be made of corrosion-resistant steel or bronze mesh with a maximum aperture of 2mm. Aluminium is not allowed.

Garage Doors (Clause 9.5.6)

Garage doors must be completely non-combustible and fitted with appropriate door seals.

Roofs and Roof Systems (Clause 9.6)

  • Materials: All roofing materials and accessories must be non-combustible and sealed appropriately.
  • Tiled/Sheet Roofs: Must conform to Appendix H of AS3959:2018 or be tested to AS1530.8.2.
  • Evaporative Coolers: Strictly prohibited.
  • Eaves & Fascias: Fascias and bargeboards must conform with AS1530.8.2. Eave linings need an FRL of —/30/30 or must conform with AS1530.8.2.
  • Gutters & Downpipes: Gutters and box gutters must be non-combustible. Box gutters require non-combustible flashing. Downpipes have no specific requirements. Gutter guards (if installed) must be non-combustible.
  • Vents: Must be fitted with ember guards made of corrosion-resistant steel or bronze (no aluminium) with a max 2mm mesh.

Verandahs, Decks, and Landings (Clause 9.7)

  • Posts: Verandah and carport posts must be non-combustible.
  • Supports & Framing (Unenclosed): Must be non-combustible or tested to AS1530.8.2.
  • Supports & Framing (Enclosed): No structural requirement if the enclosure matches wall standards.
  • Surfaces (Decking, Stairs, Ramps): Must be non-combustible, fibre-cement sheet, or a system conforming to AS1530.8.2.
  • Balustrades: Any balustrade or handrail within 125mm of glazing or a combustible wall must be non-combustible.
  • Verandah/Carport Roofs: Must match the main roof requirements or be separated by a compliant external wall.

Water and Gas Pipes (Clause 9.8)

  • Water Pipes: Above-ground exposed water supply pipes must be metal.
  • Gas Pipes: External above-ground gas pipes must be steel or copper (with a minimum wall thickness of 0.9mm or compliant with gas regulations, whichever is greater). They must extend a minimum of 400mm inside the building and 100mm underground.