In many parts of Australia, especially bushfire-prone regions such as rural fringe suburbs or areas adjacent to native vegetation, planning and building outdoor structures — including decks — involves more than just aesthetics and durability.
When a site is located in a bushfire-prone area, you must consider Bushfire Attack Level (BAL) ratings, which measure the potential severity of bushfire exposure and dictate construction requirements to reduce risk to your home and occupants.
This guide explains what BAL means, how it affects deck design and material selection, and practical steps to help your next outdoor project comply with safety standards.
What Is a Bushfire Attack Level (BAL)?
A Bushfire Attack Level (BAL) is a measurement system used in Australia to assess the level of potential exposure a building may face from a bushfire. BAL considers factors such as:
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Radiant heat
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Ember attack
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Flame contact
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Surrounding vegetation and slope
There are six BAL categories, each indicating increasing risk:
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BAL-LOW – minimal risk
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BAL-12.5 – ember attack risk
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BAL-19 – moderate ember attack/radiant heat
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BAL-29 – high ember attack and radiant heat
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BAL-40 – very high radiant heat
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BAL-FZ – extreme bushfire exposure with possible flame contact
Your local council, fire authority or an accredited assessor can determine your specific BAL for any site.
How BAL Ratings Affect Your Deck Design
Once you know the BAL rating of your property, you must follow the requirements in Australian Standard AS 3959:2018 and the National Construction Code (NCC) for decking materials and construction methods.
The higher your BAL, the more stringent the requirements. These standards aim to reduce the risk from embers, radiant heat, and direct flame contact.
BAL Requirements for Decks
Different BAL ratings impose different construction and material criteria for decks. Here’s a simplified overview:
| BAL Level | Construction Implications |
|---|---|
| BAL-LOW | Standard construction; no specific bushfire materials required |
| BAL-12.5 | Ember attack risk; standard materials allowed, careful detailing |
| BAL-19 | Moderate ember attack; materials should be non-combustible or bushfire resistant near openings |
| BAL-29 | High risk level: decking materials generally must be non-combustible or bushfire resistant; supports may need protection or non-combustible materials |
| BAL-40 | Very high bushfire exposure: subfloor, supports and decking must be non-combustible; spacing and design controls critical |
| BAL-FZ | Extreme flame contact risk: very stringent; decking generally must be non-combustible with minimal gaps and ember protections |
💡 Note: Exact requirements vary by state and local government rules — always consult local approval authorities and refer to AS 3959:2018 for detailed criteria.
Material Choices in Bushfire-Prone Zones
Timber vs Non-Combustible Materials
In lower-risk areas (BAL-LOW to BAL-19), bushfire-resistant timbers such as spotted gum, blackbutt or ironbark are often permitted for decking and outdoor elements. These species have higher natural fire resistance and are referenced within bushfire standards.
At higher BAL levels (BAL-29 and above), the regulations typically require non-combustible or highly fire-resistant materials for decking, supports and structural components. Traditional untreated softwood is often not suitable in these conditions.
Composite decking systems, particularly those engineered for fire resistance, can be an excellent choice up to moderate BAL levels — provided they are tested and certified to relevant fire standards such as AS 1530.8.1.
Designing a Bushfire-Resistant Deck
When building or specifying a deck in a bushfire-prone area, consider the following:
📌 1. BAL Assessment Early
Obtain a BAL risk assessment before design and material selection. This informs all subsequent decisions and ensures regulatory compliance.
📌 2. Choose Appropriate Materials
Select decking boards and substructure materials that meet your BAL rating requirements. Non-combustible or fire-resistant options perform better in high-risk areas.
📌 3. Minimise Ember Entry Points
Design details to avoid gaps, crevices and unprotected underfloor spaces where embers can lodge. Ember guards and mesh screening around subfloors and junctions are effective measures.
📌 4. Comply with Local Codes and Standards
Always check with your local council or private certifier for any additional requirements beyond AS 3959, as states may have specific rules.
Benefits of Using Suitable Materials Like PureSolid Decking
At PureSolid, our outdoor decking solutions are engineered to perform in a wide range of Australian conditions. While specific BAL-rated certifications depend on individual product testing and approvals, choosing materials with high fire resistance, low combustibility and durable composite performance helps provide peace of mind in bushfire-prone zones.
When designing your deck with PureSolid systems, consider:
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Fire-resistant board options
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Minimised gaps between boards where appropriate
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Non-combustible fixings and substructure detailing
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Consultation with a BAL assessor for certified compliance
This approach aligns with responsible outdoor design for bushfire safety without sacrificing long-term performance or aesthetics.
Frequently Asked Questions
Do I need a BAL rating for every property in a bushfire-prone area?
Yes — determining your BAL rating with an accredited assessor or local council ensures you comply with the correct building standards and approvals.
Can I use wood decking in a BAL-29 area?
Some bushfire-resistant timber species may be permitted up to certain BAL levels, but at BAL-29 and above, non-combustible materials are often required. Always confirm with local standards.
What if I’m in BAL-FZ (Flame Zone)?
BAL-FZ is the most severe bushfire exposure. Typically, only non-combustible materials and designs are suitable — consult AS 3959 and local authorities for exact compliance.
Does BAL apply to other outdoor structures (e.g., pergolas)?
Yes — pergolas, decks, screens and other outdoor structures may all fall under BAL considerations depending on their proximity and exposure. Always assess them as part of the overall bushfire risk.
Final Thoughts: Build Safe and Compliant
Building in a bushfire-prone area requires proactive planning and informed material selection. Understanding your Bushfire Attack Level (BAL) and complying with AS 3959 standards helps protect your home, family and outdoor investment.
For decking projects in these zones, working early with a BAL assessor and choosing fire-resistant or non-combustible materials — including appropriate PureSolid decking solutions — provides greater safety, compliance and peace of mind.