Embers arrive long before flames
The CFA describes embers as small pieces of burning twigs, leaves and debris, and calls them the main reason homes and buildings are destroyed in a bushfire. They can set fire to a house when they land in the garden, on a doormat or in gutters.
Wind carries them a long way. The CFA says the distance they would normally travel is around 10 kilometres, and that on Black Saturday in 2009 embers were carried up to 30 kilometres from the fire front.
A screen’s job against embers is simple to state: keep a burning fragment from touching glass or timber, and from getting through a window that has cracked in the heat. The CFA puts it in those terms.
Metal, and a small aperture
ENLARGED, NOT TO SCALE
1.5 mm holesmetal screens over windows (not aluminium)
2 mm maximum aperturedoor fly screens; sub-floor mesh
For windows, the CFA suggests metal screens, not aluminium, with 1.5 mm holes, fitted over both the window and its frame. For door fly screens it says the frame should be metal and the mesh corrosion-resistant bronze or steel, with a maximum aperture of 2 mm.
The NSW Rural Fire Service lists “install fine metal mesh screens on windows and doors” among its basic tips for preparing a home, next to fitting seals around doors and windows to eliminate gaps.
Where the CFA puts mesh and screens
- WindowsSeal gaps around frames; install metal screens over the window and frame. Shutters over windows and frames instead of mesh can protect even better, and can stop glass cracking from radiant heat or debris.
- DoorsUpgrade to solid timber or a non-combustible door, seal gaps, and install metal screen doors over timber doors. Glass in the door should be toughened, at least 6 mm thick.
- Sub-floorEnclose it with non-combustible materials if you can. If it is open, clear flammable things from under the house and seal gaps with corrosion-resistant bronze or steel wire mesh or perforated sheet, maximum aperture 2 mm.
- RoofSeal gaps with compressed mineral wool insulation, cover skylights with non-combustible fire screens, and cover gaps in evaporative coolers with metal mesh.
When it is a building project, not a weekend job
Standards Australia lists AS 3959, “Construction of buildings in bushfire-prone areas”. Its listing says the standard sets construction requirements that make a building better able to resist bushfire attack, whether from burning embers, radiant heat, flame contact or a combination of these. As at October 2026 the listing marks it “Pending Revision”.
In NSW, the Rural Fire Service says any proposed development on land designated bush fire prone has a legal obligation to consider bush fire and meet the requirements of Planning for Bush Fire Protection 2019, and it offers a tool to check whether your land is bush fire prone. Other states set their own rules; check with your state’s fire service or planning body.
Mesh does not replace leaving
“Leaving early is ALWAYS your safest option.” CFA
Both services frame home preparation as something you do even if you plan to leave. The RFS says a well prepared home is more likely to survive a bush fire or ember attack, can be easier for you or firefighters to defend, and gives more protection if a fire threatens suddenly and you cannot leave.
A screen fitted for embers is still a door or window someone may need to get out through. Keys, deadlocks and getting out.