How to Survive an Ember Attack
The mental image of losing a house to bushfire is a wall of flame. The reality is much quieter and much more preventable.
Research from CSIRO and the Bushfire CRC found that at least 85% of houses destroyed in bushfires never experience direct flame contact or significant radiant heat from the fire front. They are ignited by ember attack and low-level surface fire — burning bark, twigs and leaves carried by wind, landing in a gutter or blowing under a door, sometimes kilometres ahead of the fire and hours before it arrives. Some analyses put the figure closer to 90%. The ACT Coroner’s inquiry into the 2003 Canberra firestorm found that half the suburban homes destroyed were lost to ember attack directly out of the neighbouring forest.
Which means most house loss is decided by small gaps, dry material and unattended fifteen-minute windows — not by heroics.
The 10-minute version
- Clear your gutters before every season. Dry leaf litter in a gutter is the single most reliable way to start a house fire from a distance.
- Close the gaps embers get through — under doors, roof vents, evaporative cooling units, weep holes, subfloor and deck spaces. Fine metal mesh, not plastic.
- The danger lasts for hours after the front passes. Most ember-started house fires begin small and unattended. If you are staying, the job continues long after it looks over.
How ember attack actually works
Wind lifts burning material — stringybark is notorious for it — and carries it well ahead of the fire. Those embers land on and around houses. Most go out. A few land somewhere with dry fuel, shelter from wind, and nobody watching.
Three timing facts change how you should think about it:
- Embers arrive before the fire, sometimes by hours and sometimes from kilometres away. You can be under ember attack while the fire is not visible.
- Embers keep arriving after the front passes. The front is loud and brief; the ember phase is long and quiet, and it is when most houses ignite.
- A house fire starts small. A gutter smoulders, a deck ignites, a curtain catches inside a broken window. Fifteen minutes of nobody looking is the difference.
Entry points, ranked
Ordered by how often they matter.
1. Gutters and roof valleys. Dry leaves in a metal tray, in wind. Clear them at the start of the season and again mid-season if you are under trees. Gutter guard helps but does not remove the need to check.
2. Under doors and around windows. A gap under an external door will take an ember straight onto carpet or floorboards. Draught excluders and door seals are a few dollars each.
3. Roof vents, whirlybirds and eaves. Openings straight into a roof cavity full of dry timber and insulation. Fine metal mesh over every one.
4. Evaporative air conditioners. An open path into the house with a fan. Cover the unit, and know how to shut it off. This is a genuinely common ignition route and it surprises people.
5. Decks, subfloors and under-house storage. Anything stored under a deck — timber, boxes, the spare mattress, the fuel can — is a fuel pile with a roof over it. Clear it out and screen the perimeter.
6. Weep holes and wall vents. Small, numerous, often forgotten. Fine mesh.
7. Flammable material against the walls. Firewood stacks, mulch, garden beds of bark chip, doormats, outdoor furniture cushions, hanging baskets. Move it or remove it.
8. Broken windows. Radiant heat cracks glass, then embers enter. Shutters or screens help; internal wool blankets over windows are a last-resort improvisation.
9. Skylights and roof penetrations. Older ones especially.
10. Sheds, fences and neighbouring structures. A timber fence is a fuse that runs to your house. A metal gate section or a gap near the house breaks the run.
The 30-minute pre-arrival routine
If you are staying, and embers are expected, this is the sequence. If you are leaving, do the parts you can and go — the trigger table in Leave or Stay? decides which.
- Fill gutters with water if you have a gutter plug, or block downpipes and fill. Wet leaf litter is much harder to ignite.
- Fill baths, sinks, tubs and buckets. Mains pressure fails; you want water already inside.
- Turn off evaporative cooling and cover the unit.
- Close all windows and doors, including the roller door and any internal doors — internal doors slow fire spread if it does get in.
- Bring in or move away doormats, cushions, outdoor furniture, hanging baskets, and anything else that will catch.
- Move the firewood and the fuel can away from the house.
- Wet down the immediate perimeter — the deck, the walls, the garden beds against the house. Not the roof, and not so early that it dries before the embers arrive.
- Dress in the protective clothing — cotton or wool long sleeves and trousers, leather boots, gloves, goggles, P2 mask.
- Put buckets and mops in every room, plus a torch.
- Set up the pump and test it. Now, not when you need it.
After the front: the part people get wrong
The fire front passes in minutes. The ember phase can run for hours, and it is when most houses are lost — often after the occupants have relaxed, gone inside, or left believing it is over.
Patrol. Every room, the roof cavity if you can access it safely, the deck, under the house, the perimeter. Repeatedly, for hours.
Look for smoke, not flame. An ember fire announces itself as a wisp and a smell long before there is anything visible to fight.
Check the roof cavity. An ember through a vent smoulders in insulation for a long time before it becomes obvious.
Do not go back to bed. The single most common way a defended house is lost.
What actually goes wrong
Gutters were never cleared. Everything else is secondary to this.
Plastic mesh instead of metal. It melts, which converts a screen into a hole exactly when it matters.
The evaporative cooler was left running. A fan pulling embers into the house.
Wood stacked against the wall, or stored under the deck.
Everyone relaxed after the front passed. The ember phase is longer and quieter than the front.
No water inside the house. Mains pressure fails, and a bucket in the bathroom is what puts out a curtain.
Synthetic clothing. It melts onto skin. Cotton, wool or denim only.
The plan assumed the fire would be visible. Embers travel kilometres. You can be defending against a fire you cannot see.
Thresholds
| Situation | The rule |
|---|---|
| Start of fire season | Gutters cleared, mesh checked, under-deck cleared, fuel and wood moved |
| Rating hits High | Yard clear of loose flammables, hoses connected and tested |
| Rating hits Extreme | Bag in the car. Plan is live |
| Embers expected, staying | Run the 30-minute routine. Full PPE on before it starts |
| During the ember phase | Patrol continuously. Look for smoke, not flame |
| After the front | Patrol for hours, including the roof cavity. Nobody sleeps |
| Any window breaks | Close the internal door to that room. Contain, then deal with it |
| Defence failing | Fall back to the pre-decided position. Property is insurable |
What it costs
| Tier | Spend | What it buys |
|---|---|---|
| Free | $0, one afternoon | Gutters cleared, under-deck cleared, firewood moved, loose flammables removed, doors and windows sealed with what you have |
| Solid | ~$150–400 | Fine metal mesh for vents and weep holes, door seals and draught excluders, gutter plugs, buckets and mops, P2 masks and goggles |
| Serious | $2,000–10,000+ | Ember screens on all openings, gutter guard, metal shutters, an independent water supply and a petrol pump, replacing timber fencing near the house |
The free tier prevents more house losses than the expensive tier, because the dominant failure is dry material in gutters and under decks rather than an absence of shutters.
The drill: the pre-season walk-around
Once a year, early October, forty minutes with a notepad.
- Ten minutes. Look in the gutters. Actually look, with a ladder, not from the ground.
- Ten minutes. Walk the perimeter. Every vent, weep hole, door gap and window. Note what has no mesh and what has gaps.
- Five minutes. Look under the deck and under the house. Empty it.
- Five minutes. Note everything flammable within a metre of a wall. Move it or plan to.
- Five minutes. Find the evaporative cooler switch and the roller door manual release. Show someone else.
- Five minutes. Turn on every tap and hose. Confirm they reach every side of the house.
Then buy the short list and fix it in one weekend. It is the highest-return home maintenance in the country if you live anywhere near bush.
Frequently asked questions
What percentage of homes are lost to embers rather than flames?
Research from CSIRO and the Bushfire CRC found at least 85% of houses destroyed in bushfires never experience direct flame contact or significant radiant heat, with ember attack and low-level surface fire responsible. Some analyses put it nearer 90%.
How far ahead of a fire can embers travel?
Kilometres. Embers are carried well ahead of the front by wind, which means your house can be under ember attack while the fire itself is not visible from your property.
What is the single most important thing to do?
Clear your gutters before the season and check them again mid-season if you are under trees. Dry leaf litter in a metal gutter is the most reliable ignition point on a house.
Do I need to worry about my evaporative air conditioner?
Yes. It is an open path into the house with a fan behind it. Turn it off and cover the unit when embers are expected, and know where the switch is before the day.
When is the danger over?
Long after the front passes. The ember phase runs for hours and is when most house losses occur. Patrol continuously — including the roof cavity — and do not go to bed.
Does plastic mesh work for screening vents?
No. It melts precisely when it is needed. Use fine metal mesh on vents, weep holes and under-deck perimeters.