Every year we get calls from clients in Mulgoa, Wallacia, Regentville, Werrington Downs and the west side of Cranebrook asking why the local council knocked back their window replacement DA. The usual reason: BAL-rated glass. If your property sits on the bushfire-prone land register, standard aluminium windows are not compliant. Here is the practical version, without the code-speak.
What BAL actually means
BAL stands for Bushfire Attack Level. It is a rating in Australian Standard AS 3959 that quantifies how much radiant heat and ember attack a building is exposed to during a bushfire. There are six levels, from lowest to highest exposure:
- BAL-Low: minimal risk. No specific glass requirements.
- BAL-12.5: ember attack, some radiant heat. Most common on Penrith fringe properties.
- BAL-19: increased radiant heat plus embers.
- BAL-29: significant heat plus embers plus limited direct flame.
- BAL-40: intense heat plus embers plus significant direct flame.
- BAL-FZ (Flame Zone): direct flame contact possible. Highest rating.
Council or a bushfire consultant assigns your BAL rating based on distance from vegetation, slope, and fuel load. Most Penrith fringe properties come in at BAL-12.5 or BAL-19.
What each rating means for glass
BAL-12.5 and BAL-19 usually require:
- Toughened glass 5 mm minimum in the outer pane, or
- Grade A safety glass to AS/NZS 2208 with additional ember screening.
BAL-29 usually requires:
- Toughened glass 6 mm minimum outer pane, and
- Framed to prevent ember entry, and
- Fly screens rated to 2 mm aperture maximum, corrosion resistant.
BAL-40 and BAL-FZ get very specific. Full IGU with tempered laminated outer, non-combustible frame, radiant heat testing, and typically shutters. These jobs are rare in Penrith but we do them for properties on the Nepean escarpment and further west.
Aluminium frames and BAL
Aluminium melts at around 660 degrees. Radiant heat from a serious bushfire can push surface temperature well above that. For BAL-29 and above you generally need either:
- Aluminium frame with a specific bushfire-rated intumescent gasket set (available from most Australian window suppliers as an add-on).
- Or a rated composite / steel frame system.
For BAL-12.5 and BAL-19 standard aluminium is compliant provided the glass and screens meet spec.
The screen question
Most people asking about BAL glass forget the screens. Every openable window in a BAL-rated home needs a rated flyscreen. Standard nylon or fibreglass mesh does not comply. You need:
- Bronze, aluminium or stainless steel mesh.
- Maximum aperture 2 mm (some ratings) or as specified in your BAL certificate.
- Framed in a BAL-compatible frame with rated fixings.
Retrofitting new BAL-rated flyscreens to existing windows is often the cheapest starting compliance move if your frames and glass are already close.
How to find out your BAL rating
Three options:
- Council DA process for a new build or renovation. Council commissions or requires a bushfire assessment.
- NSW Rural Fire Service planning tool. Free online lookup based on your address.
- Private bushfire consultant. Around $600 to $1,200 for a full BAL report suitable for insurance and DA.
If you are just refreshing existing windows and not extending, a formal report is not always mandatory, but installing BAL-rated glass anyway is a smart move on a fringe property because insurance premiums have historically been friendlier for compliant properties.
Insurance implications
Every insurer we deal with either offers a discount or waives an excess load for properties with fully BAL-compliant glazing. Ask your insurer what they credit before you sign off on the spec, then let us know so we document the upgrade appropriately for your records.
Cost impact
BAL-12.5 grade toughened glass costs about 15 to 25 percent more than standard toughened. BAL-29 with intumescent framing runs 40 to 60 percent above standard aluminium. BAL-40 and FZ are quoted per project because they usually involve custom framing systems.
For a full house of BAL-12.5 windows on a typical Penrith fringe home (12 to 15 openings), budget an additional $3,500 to $6,000 over standard aluminium framing.
What we ask before quoting a BAL job
- Your BAL rating (or the RFS lookup result if you have not commissioned a report).
- Whether this is a new build, renovation, or straight replacement.
- Whether council or private certifier is signing off.
- Photos of the existing openings, or plans if new build.
See the Windows and Doors overview for the standard configurations we can upgrade to BAL spec, and the commercial window repair service for context on how we handle rated glazing projects at scale. Any question, ring 02 4722 2787 or send it through the contact form.
