Defensible space is the buffer zone you create between your home and the grass, trees, shrubs, and other vegetation that surround it. It is the single most effective action a homeowner can take to improve the chances of their home surviving a wildfire — and to give firefighters a safe place to work if they defend your property.
When a wildfire approaches, it does not simply arrive as a wall of flame. Embers travel kilometres ahead of the fire front, landing on roofs, in gutters, against fences, and in dry vegetation beside your house. The majority of homes that burn during wildfires are ignited by these airborne embers, not by the main flame front. Defensible space directly reduces this ember risk by eliminating the fuels closest to your structure.
⚠️ In many jurisdictions, maintaining defensible space is a legal requirement. Failure to comply can result in fines and may affect your insurance coverage. Check your local fire authority regulations before any major changes.
Understanding the Two Zones
Defensible space is typically divided into two distinct zones, each with specific vegetation management requirements.
| Zone | Distance from Home | Goal |
|---|
| Zone 1 (Lean, Clean, Green) | 0–9 metres (0–30 ft) | Eliminate or drastically reduce combustible plants and materials |
| Zone 2 (Reduced Fuel Zone) | 9–30 metres (30–100 ft) | Reduce fuel density so fire cannot crown and travel to Zone 1 |
| Extended Zone (slopes) | Up to 30–60 m additional | Compensate for slope-accelerated fire spread |
| Ember-ignition zone | Under eaves, in gutters, vents | Prevent ember catch in structural gaps |
On sloped land, zones must be extended further downhill. A 10% slope increases effective fire travel speed significantly — add 10 extra metres of Zone 2 for every 10% of slope gradient.
Zone 1: The Lean, Clean, Green Zone (0–9 metres)
This is the most critical zone. Vegetation here must be carefully managed year-round.
Plants and vegetation:
- Remove all dead plants, grass, and weeds
- Mow grass to a maximum height of 10 cm (4 inches)
- Choose fire-resistant plants with high moisture content (succulents, deciduous species)
- Space plants so fire cannot travel continuously from one to the next
- Remove all branches within 3 metres of the ground on any tree
- Keep any tree canopy at least 3 metres away from your roof and chimney
Structures and materials:
- Clear gutters of dry leaves and pine needles after every wind event and before fire season
- Remove combustible furniture, doormats, and decorations from decks during high-risk periods
- Store firewood at least 9 metres from your home
- Replace wood fencing touching the house with metal or masonry sections
- Ensure garden hoses can reach all corners of Zone 1
Common Zone 1 mistakes to avoid:
- Planting conifers or eucalyptus close to the house (highly flammable even when green)
- Allowing ivy or ground-cover vines to contact the exterior wall
- Leaving a wooden deck with combustible materials stored beneath it
- Placing mulch directly against the foundation wall (use gravel instead)
Zone 2: The Reduced Fuel Zone (9–30 metres)
Zone 2 is about breaking the continuity of fuel so that a surface fire cannot climb into tree canopies and become a crown fire, which travels far faster and generates more radiant heat.
Tree spacing:
- Space trees so crowns do not touch — minimum 3–5 metre gaps between canopy edges
- On steep slopes, increase spacing: trees further downhill require greater separation
- Remove all dead trees and standing dead wood (snags) unless they provide wildlife habitat at a safe distance
- Limb up all trees to remove branches within 3 metres of the ground
Shrubs and understorey:
- Group shrubs in islands with bare soil or low-lying plants between groups
- Remove shrubs growing directly beneath tree canopies
- Mow or cut back annual grasses before they dry out in summer
| Slope Gradient | Zone 2 Minimum Radius |
|---|
| Flat (0–10%) | 30 metres |
| Moderate (10–20%) | 40 metres |
| Steep (20–30%) | 50 metres |
| Very steep (>30%) | 60+ metres |
Hardening Your Home Against Embers
Defensible space vegetation work must be paired with home hardening to be truly effective. Embers can enter a structure through surprisingly small openings.
Vents and openings
- Cover all attic and foundation vents with 1.5 mm (1/16 inch) or finer metal mesh
- Install spark arrestors on chimneys
- Seal any gaps in soffits, eaves, and around pipes with metal mesh or caulk
- Keep garage doors closed during wildfire events
Roof and gutters
- Choose non-combustible roofing: metal, tile, or Class A asphalt shingle
- Install gutter guards to prevent leaf accumulation
- Consider ember-resistant gutter covers made from metal mesh
Walls and windows
- Double-pane or tempered glass windows are more resistant to radiant heat
- Cover vents behind shutters during evacuations
- Remove combustible awnings and replace with metal or fire-resistant alternatives
Decks
- Fill gaps in deck boards where embers can accumulate underneath
- Use non-combustible skirting around the deck perimeter
- Store all combustible cushions and furniture indoors during red flag conditions
Seasonal Maintenance Schedule
Defensible space is not a one-time project — it requires ongoing maintenance tied to the seasonal fire cycle.
Spring (before fire season):
- Inspect the entire Zone 1 boundary after winter rains
- Remove any new seedlings or volunteer plants within 3 metres of the house
- Apply 5 cm of gravel mulch around the foundation to replace any organic mulch
- Test all garden hoses and outdoor taps for full functionality
- Clear gutters of winter debris — leaves, pine needles, and seed pods
Early summer:
- Mow grass in both zones before it dries out
- Cut back any shrubs that have grown into prohibited spacing
- Remove lower limbs of trees if new growth has lowered canopy height
- Inspect roof surface for any accumulated plant debris
- Clean wood-burning fireplace and check chimney cap is intact
During fire season:
- Check Zone 1 after every wind event for accumulated debris
- Remove combustible items from deck and patio during red flag warnings
- Know your evacuation trigger — do not wait for official orders if fire is near
- Keep vehicles facing out with keys accessible, fuel tank above half
Autumn:
- Conduct a full Zone 1 and Zone 2 inspection
- Document improvements with photographs for insurance records
- Clear gutters again before the first winter rains
- Dispose of green waste promptly — do not allow piles to dry near the house
Selecting Fire-Resistant Plants
Not all plants are equally flammable. Fire-resistant plants tend to be high in moisture content, low in resin or volatile oils, and non-accumulating of dead material. They do not eliminate fire risk but significantly reduce it.
Preferred characteristics:
- Leaves with high moisture content that do not dry and curl in heat
- No accumulation of dead material within the plant structure
- Low sap or resin content
- Open branching structure rather than dense foliage masses
Plants to avoid in Zone 1:
- Conifers (pines, firs, spruces) — resinous and highly flammable
- Ornamental grasses — dry out and carry fire rapidly
- Rosemary and lavender — aromatic oils are highly volatile
- Bamboo — hollow stems act as a chimney when burning
- Any plant with shreddy or papery bark
⚠️ Even fire-resistant plants will burn under extreme fire conditions. The goal is to slow fire spread and reduce the heat reaching your home — not to create a fireproof landscape.
Working With Neighbours and the Community
Defensible space that ends at your property line provides less protection than a community-wide approach. Embers travel freely across property boundaries, and a neighbour's neglected vegetation becomes your hazard.
- Share defensible space information with adjacent neighbours before fire season
- Offer to help elderly or mobility-limited neighbours clear their zones
- Contact your local fire authority about free vegetation inspection programmes
- Participate in community FireSafe councils or equivalent local bodies
- Advocate for local government weed abatement programmes on roadsides bordering your community
Quick Reference
| Task | Zone 1 Requirement | Zone 2 Requirement | Frequency |
|---|
| Grass mowing | ≤10 cm height | Cut before dry season | Monthly in season |
| Tree limbing | No branches <3 m high | No branches <3 m high | Annual |
| Tree crown spacing | Canopy 3 m from roof | Crowns 3–5 m apart | Annual check |
| Gutter clearing | Remove all debris | N/A | After each wind event |
| Dead plant removal | All dead material removed | Remove dead trees | Annual |
| Firewood storage | 9 m minimum from home | Stacked neatly | Ongoing |
| Vent screens | 1.5 mm metal mesh | N/A | Inspect annually |
| Mulch type | Gravel only at foundation | Organic mulch acceptable | Replace as needed |