Bushfire Roof Protection

In Australia, the risk of bushfire to a building is measured using Bushfire Attack Levels (BAL), defined in AS 3959. BAL ratings range from BAL-LOW (no significant risk) through BAL-12.5, BAL-19, BAL-29 and BAL-40 to BAL-FZ (Flame Zone, the highest risk). Your property's BAL rating is determined by the type of vegetation surrounding it, the distance from that vegetation, and the slope of the land. Across Gippsland, many properties in the Strzelecki Ranges, Baw Baw foothills, East Gippsland forests and bushland fringe areas carry BAL ratings that impose specific building requirements. Your local council can advise on the BAL rating applicable to your property.

During a bushfire, the primary threat to most homes is ember attack rather than direct flame contact. Wind carries burning embers ahead of the fire front — sometimes kilometres ahead — and these embers seek entry into buildings through gaps, vents and openings. The roof is the most vulnerable part of your home because embers land on it, accumulate in gutters and valleys, and enter through gaps around ridge caps, barges and eave lines. Once embers enter the roof cavity, they can ignite timber framing, insulation and stored items. Research by the CSIRO has consistently shown that ember attack is responsible for the majority of house losses during Australian bushfires.

Non-combustible roofing materials are required in all BAL-rated areas. Colorbond steel, Zincalume, corrugated iron, concrete tiles and terracotta tiles are all non-combustible and suitable for bushfire areas. Polycarbonate roofing is combustible and generally cannot be used in BAL-rated zones. Beyond the material itself, the complete roof system matters — sarking should be non-combustible in higher BAL ratings, and all flashings, seals and components must meet the relevant standard. For BAL-FZ (Flame Zone), the entire roof assembly must be tested and certified to resist direct flame contact and radiant heat.

Even if your roof is made from non-combustible material, embers can enter through gaps. Key ember-proofing measures include: installing metal gutter guards (preferably steel mesh with apertures no larger than 2 mm) to prevent ember accumulation in gutters; sealing gaps around ridge caps with non-combustible filler or foam; fitting ember-proof seals to barges and eave closures; ensuring roof-mounted vents have ember-proof mesh screens; and blocking any gaps where pipes, cables or antenna mounts penetrate the roof surface. All sealing materials must themselves be non-combustible or have a low flammability rating.