BAL-rated windows: what bushfire-zone Victorians need to know

The focus is stopping embers and resisting moderate radiant heat. The standard requires: 

• Bushfire-resistant mesh on openable parts of the window, with apertures of 2mm or smaller, in corrosion-resistant steel, bronze, or aluminium 

• Grade A safety glass minimum 4mm thick on glazing within 400mm of the ground or any other surface 

• Tightly-sealed gaps around the frame so embers can’t get through 

• Frames in compliant materials: listed timber species, aluminium, steel, or metal-reinforced uPVC under the deem-to-satisfy pathway, or a tested system 

Requirements step up significantly. The whole window system has to be tested as a unit: 

• Toughened glass minimum 5mm at BAL-29 and 6mm at BAL-40 (heat-strengthened glass alone does not meet the standard) 

• Frames must be tested for the rated BAL or built from materials listed as compliant for that level 

• Operable sashes face stricter sealing rules to resist flame contact 

• Screens, mesh, and seals are part of the tested system, supplied with the unit 

A separate engineering problem. Most residential window systems sold in Australia don’t reach Flame Zone compliance. If a property assesses to BAL-FZ, the design conversation usually moves to fire-rated wall systems with smaller, specifically-engineered openings rather than standard window products. 

One thing the table doesn’t show: BAL-rated windows still need to perform on energy efficiency. A bushfire-rated window with a U-value of 4.0 will pass the bushfire requirement and fail the 7-star NatHERS modelling. The window has to do both jobs, which narrows the supplier list quickly. 

uPVC frames aren’t inherently bushfire-rated. Nothing is. The standard tests the system as a unit: frame, glass, hardware, and seals together. A frame that performs at BAL-29 in one configuration may not in another, which is why suppliers report ratings on a per-product basis against tested configurations. 

There are two ways uPVC can comply. The deem-to-satisfy pathway allows metal-reinforced uPVC frames at BAL-12.5 to BAL-29. Above that, the system has to be tested to AS 1530.8.1:2018. Suppliers who hold that certification list it explicitly with the testing authority and product configuration. 

Weatherall’s tilt and turn windows, smart slide doors, and hinged doors can be manufactured to meet BAL 40, the highest level reachable for residential uPVC systems short of full Flame Zone compliance. That covers the great majority of Victorian Bushfire Management Overlay properties outside Flame Zone classification, including most of the Macedon Ranges, Yarra Valley, Dandenong Ranges, and central highlands country where higher BAL ratings are most likely to apply. 

A point on testing: because Weatherall manufactures its windows in Campbellfield, the certification covers the system as it leaves the factory. The BAL rating attaches to a specific tested configuration, and the chain between the rating and the unit on site is shorter when the manufacturer holds the certification directly. 

If your property has assessed at BAL-FZ, Weatherall’s products won’t be the answer. The design conversation moves to specifically-engineered fire-rated wall construction. 

Three steps, in order: 

1. Check whether the property is in a designated Bushfire Prone Area (BPA) or a Bushfire Management Overlay (BMO). The Victorian Building Authority (vba.vic.gov.au) and the Vic.gov.au planning maps both let you check by address. Your local council planning department can also confirm. A property can sit in a BPA without being in a BMO. The BMO is the more restrictive of the two, and it triggers a planning permit and a formal BAL assessment.
2. For new builds and significant renovations, commission a BAL assessment. This is done by a registered bushfire consultant, typically as part of the planning application. The assessment walks the site and applies AS 3959 to the vegetation, slope, and proximity. The cost is usually a few hundred dollars. Cheap relative to the cost of getting it wrong.
3. Check whether your property has been re-mapped. BPA and BMO mapping is reviewed periodically (the Victorian BPA has been amended more than 20 times since the original 2011 gazettal). A property that wasn’t restricted ten years ago may be now. If you’re replacing windows in an older home and you haven’t checked recently, do it before you spec the glazing. 

Under Victorian Building Regulations 2018, Items 157 and 158, Class 1, 2, 3, 4, 9a, 9b, or 10a buildings in a designated Bushfire Prone Area must be built to a minimum of BAL-12.5. That covers most homes, granny flats, and small commercial buildings. The minimum is the floor; the assessment determines whether the requirement is higher. 

Five questions worth asking before you commit: 

1. What BAL is your product tested to, and can you provide the certification? The certification should name the testing authority and the tested product configuration, usually under AS 1530.8.1:2018. A supplier who can’t produce it on request is a supplier who hasn’t tested. 
2. Is the rating for the whole system, or just the frame? This matters. The frame alone passing a heat test doesn’t mean the assembled unit will. Ask for system-level certification covering frame, glass, hardware, and seals together. 
3. Does the rating cover the configurations you want? Tilt and turn, sliding, hinged, fixed: each is a different system and may carry a different rating. Confirm the rating applies to the configuration you’re specifying. 
4. What sizes are available at the rated BAL level? Some suppliers downgrade ratings on larger sizes because the testing was done at a smaller dimension. If you want a 3.5-metre sliding door, ask whether the rating still applies. 
5. Are screens, mesh, and seals included, or specified separately? At higher BAL levels, the bushfire-resistant mesh is part of the tested system. Confirm they’re quoted, not assumed.