What Is Defensible Space?

Defensible space is the buffer zone you create between your home and the surrounding vegetation or other combustible materials. It gives firefighters a safer place to work, slows the advance of fire towards your structure, and reduces the amount of radiant heat and embers that reach your home.

In fire-prone areas of Western Australia, maintaining adequate defensible space isn't just good practice — in many local government areas it's a legal requirement under the Bush Fires Act 1954.

The Zone Approach

Think of defensible space in three zones radiating out from your home:

Zone 1 — Immediate Zone (0–10 metres)

This is the area immediately surrounding your structure. The goal here is to minimise all combustible materials.

  • Remove dead vegetation, leaf litter, and bark mulch within 1.5 metres of the house.
  • Keep grass mown short — ideally below 10cm during fire season.
  • Avoid storing firewood, timber offcuts, or gas cylinders against the house.
  • Use non-combustible mulch (gravel, pebbles) in garden beds close to the structure.
  • Screen vents, eaves, and gaps to prevent ember entry.

Zone 2 — Intermediate Zone (10–30 metres)

In this zone, the aim is to reduce fuel load and interrupt the path fire can travel to your home.

  • Thin out shrubs and trees so they are spaced well apart, removing the ladder effect where ground-level plants connect to tree canopies.
  • Remove any dead branches from trees, especially those hanging over the house.
  • Keep grass cut and maintained throughout fire season.
  • Create separation between tree canopies — a minimum of 3 metres between crown edges is a useful guide.

Zone 3 — Outer Zone (30–100 metres, where applicable)

On larger properties, this outer zone focuses on reducing the overall intensity of any fire approaching from the bush.

  • Selectively thin dense vegetation and remove highly flammable species.
  • Clear dry grass and leaf litter regularly.
  • Consider strategic placement of low-flammability plants (many native species have reduced flammability compared to exotics like cypress and pine).

Plant Selection Matters

Not all plants carry equal fire risk. When landscaping near your home, favour plants that:

  • Have a high moisture content in their leaves
  • Produce less bark, resin, or dry litter
  • Grow slowly and remain compact

Avoid highly flammable species such as conifers, ornamental grasses, and dense shrubs that dry out quickly. Your local council or the Department of Fire and Emergency Services (DFES) can provide lists of lower-flammability plant options suitable for your region.

Maintenance Is Ongoing

Defensible space is not a one-time project. Vegetation regrows, leaf litter accumulates, and gutters fill with debris. Set a regular maintenance schedule:

  1. Pre-season (March–May in WA): Major clear-up, gutter clean, check vents and screens.
  2. Monthly during fire season: Mow grass, clear gutters, check woodpiles and gas cylinder placement.
  3. Post-season: Assess what worked, repair any damage, plan any additional improvements.

Don't Forget the Structure Itself

Defensible space works best alongside a fire-resilient home. Check that:

  • Roof and wall junctions are sealed against ember entry
  • Windows are fitted with metal fly screens
  • Decks and verandahs don't accumulate leaf litter underneath them
  • Garden furniture and other combustibles can be moved inside when a warning is issued

Key Takeaway

You don't need to clear every tree from your property. You need to create a managed, well-maintained space that interrupts fire's path and reduces its intensity. Start close to the house and work outward. Every improvement you make increases your home's chance of surviving a bushfire — and gives firefighters a fighting chance if they need to defend it.