Defensible space around your home
Defensible space is the managed buffer of cleared vegetation between your house and surrounding wildland. Two zones, specific tasks in each — based on NFPA Firewise USA and CAL FIRE guidance.
Short answer
Zone 1 (0–30 ft / 9 m): essentially non-combustible — clear all dead vegetation and combustibles from around the house. Zone 2 (30–100 ft / 9–30 m): reduce and space fuel — mow, prune, and remove dead trees. On slopes, extend both zones further.
Zone tasks
What to do in each zone
Non-combustible buffer
- Remove all dead plants, leaves, and weeds
- Clear any mulch or bark chips within 5 cm of foundation walls
- Move firewood, propane tanks, and combustible storage to Zone 2 or beyond
- Keep grass mowed to under 10 cm and watered if possible
- Remove any branches overhanging the roof
- Replace combustible decking and fencing with non-combustible alternatives where practical
Reduced and spaced fuel
- Keep grass mowed short — dry grass is a fast-moving fuel
- Space shrubs so they are not continuous (no "fire ladder" to tree canopy)
- Remove lower tree branches to a height of 2 m (6 ft)
- Remove dead or dying trees
- Keep spacing between tree crowns — no touching canopies
Slopes: adjust your zones uphill
Fire travels faster uphill. On a 20% slope, fire can travel twice as fast as on flat ground; on a 40% slope, four times as fast. CAL FIRE slope adjustments recommend extending Zone 1 to 15 m (50 ft) on moderate slopes and Zone 2 to the full 30 m (100 ft) on all slopes, with extended clearing on the downhill side where fire originates. If your house sits on a ridge or hillside, assume worst-case fire approach from below.
Ember-resistant features
Defensible space reduces direct flame threat. Ember resistance addresses the other major ignition pathway — burning embers carried up to a mile ahead of the fire. The most cost-effective ember-resistant measures are: 1/16 inch (1.6 mm) mesh screening on all foundation vents, eaves, and attic vents; cleared gutters (metal gutters with gutter guards are ideal); and no combustible storage beneath decks or against walls. NIST wildfire research has shown that homes lost in wildfires often ignite from embers accumulating in gutters or against walls, not from direct flame impingement.
1 mile
Distance embers can travel ahead of a wildfire front in high winds. Source: NFPA wildfire research.
Maintenance schedule
Defensible space must be maintained — not created once and forgotten. Vegetation grows back, leaves accumulate, and new combustibles appear. Inspect Zone 1 monthly during fire season and clear after every significant wind event. Zone 2 should be walked at the start of each fire season (typically April in the western US) and again mid-season. Check your local fire agency for any additional jurisdiction-specific requirements.
For a complete wildfire household preparation checklist, see the wildfire season readiness article and the wildfire use case checklist. If you are in an active fire risk area, also review how to get out safely and what to include in a wildfire go-bag.
Primary sources: NFPA Firewise USA · CAL FIRE defensible space · NIST Fire Research Division
Defensible space FAQ
Questions about creating defensible space
It does not stop a wildfire — but it significantly changes the outcome. Research by NFPA's Firewise USA programme and CAL FIRE consistently shows that homes with cleared defensible space and ember-resistant features survive at dramatically higher rates than adjacent homes without them — even in the same fire event. Defensible space also gives firefighters a safer position from which to defend your home if resources allow.
In California, CAL FIRE regulations require 100 feet (30 m) of defensible space for properties in the State Responsibility Area — this is enforced. Other US states in high-risk zones have similar or overlapping local requirements. The NFPA Firewise USA programme provides guidance applicable to any wildland-urban interface property. In Australia, CFA Victoria has its own zone-based requirements.
Zone 1 (0–9 m / 0–30 ft from the structure) is the most critical: it should be essentially non-combustible. Remove all dead plants, dry leaves, mulch within 5 cm of the foundation, and any combustible material against the building. Zone 2 (9–30 m / 30–100 ft or to the property boundary, whichever is less) reduces fuel through spacing and height management — keep grass mowed short and ensure no continuous vegetation path would allow fire to run toward the structure. On slopes, both zones extend further because fire travels faster uphill.
Decks and fences that connect directly to the house act as a fuel bridge — fire can travel along a wooden fence from vegetation to the structure. Use non-combustible materials (composite decking, metal or masonry fencing) within Zone 1 where possible. If wooden decking is present, keep the area under the deck completely free of debris and combustible storage. NIST fire research has specifically studied deck-to-structure fire spread as a major pathway in wildland-urban interface fires.
Embers — burning fragments of vegetation or building material — are carried by wind ahead of the main fire front. They are the number one cause of structure ignition in wildfires, responsible for more home losses than direct flame contact. Embers enter structures through open vents, gaps under doors, open windows, and gutters filled with dry debris. NFPA wildfire research recommends 1/16 inch (1.6 mm) wire mesh on all vents, self-closing exterior doors, and cleared gutters as the most cost-effective ember-resistant measures. If you need to evacuate, use our wildfire go-bag checklist to prepare in advance.