Understanding AS 3959: A Plain English Guide for Homeowners
Building in a bushfire-prone area means complying with AS 3959—but what does that actually mean for your home?
This guide breaks it down in clear, practical terms so you can confidently move forward with your project knowing what’s required — and why it matters.
What Is AS 3959?
AS 3959 – Construction of Buildings in Bushfire-Prone Areas is the Australian Standard that outlines how homes must be designed and built to improve their resistance to bushfire.
It’s directly linked to your Bushfire Attack Level (BAL) rating — which is determined through site assessment and considers factors like vegetation type, distance, and slope. Each BAL category corresponds to a specific section of AS 3959, with construction requirements that increase as bushfire risk intensifies.
If you're unfamiliar with BAL ratings or how they are calculated, see our related article:
Understanding BAL Ratings: What It Means, How It's Calculated, and What to Do Next
Why It Matters
AS 3959 isn’t a guideline — it’s a mandatory requirement under the National Construction Code and planning regulations in every bushfire-prone area.
Your BAL rating tells you which section of the standard applies to your project, and that determines key building specifications. These include:
What materials can be used for external walls and windows
How gaps and joins must be sealed to prevent ember entry
Whether decks, subfloors, and roofs must be built with non-combustible products
Specific measures to protect openings, vents, and roofing systems
Failure to comply can result in delays at council, costly redesigns, or even non-certification at completion.
Construction Requirements by BAL Level
As the BAL level increases, so do the construction standards required under AS 3959. Here's a general overview:
BAL–Low
Minimal bushfire threat. No special construction requirements apply.
BAL–12.5
Requires basic ember protection. Openings such as vents and weep holes may need screening, and some materials may be restricted.
BAL–19
Introduces more stringent protections, including tighter glazing requirements, sealed gaps, and limitations on external finishes.
BAL–29
Requires use of non-combustible cladding, ember-proofing of subfloors, upgraded roofing systems, and greater attention to construction details.
BAL–40
At this level, construction must incorporate fully non-combustible materials, enclosed subfloors, sealed roof-to-wall junctions, and fire-resistant glazing.
BAL–FZ (Flame Zone)
Highest level of risk. Requires extensive fire-rated construction, drastically increased costs, and in many cases a performance-based solution backed by a specialist report.
What AS 3959 Covers in Practice
Some examples of what may be required under AS 3959 (depending on your BAL rating) include:
Fire-resistant cladding and insulation
Metal flyscreens on windows and doors
Sealed external gaps and junctions to block ember entry
Gutter guards and leaf-proof roofing features
Glazing upgrades (such as toughened or double-glazed windows)
Non-combustible materials for decks, balconies, and stairs
These features aren’t just about compliance — they’re about protecting life and property when bushfire conditions become extreme.
What You Need to Do
If you're a homeowner planning to build or renovate in a bushfire-prone area, here’s how to stay compliant:
Get an assessment done to confirm your BAL rating and understand which section of AS 3959 applies
Ensure your design and construction plans reflect the relevant BAL construction standards
Work with a builder experienced in bushfire-rated construction
Submit accurate and aligned documentation to your building certifier or council
Budget for bushfire upgrades early in the process, especially at higher BAL levels
Need Help Navigating AS 3959?
At Bushfire Smart, we specialise in helping homeowners, builders, and developers understand their obligations under AS 3959 and achieve safe, compliant construction outcomes.
Whether you need a BAL Assessment, a full Bushfire Management Plan, or just expert advice — we’re here to help.
Contact us today for a free quote or to speak with a qualified bushfire consultant about your project.