Defensible space: the three zones.
A managed buffer between your house and the wildland, designed so that fire arriving at the property line runs out of fuel before it reaches the structure.
Why defensible space
Post-fire investigations of the Camp Fire, Marshall Fire, and Palisades Fire found the same pattern: homes that survived usually had cleared Zone 0, cleared gutters, ember-resistant vents, and a Class-A roof. Homes that burned usually had bark mulch or a wood fence within 5 feet of the siding. Two houses on the same street can score very differently — the difference is what happens between the property line and the wall.
Zone 0: 0-5 feet, ember-resistant
The most important zone, and the one homeowners resist the most because it means changing the landscape closest to the house. Rules:
- No combustible mulch. Replace bark and shredded wood with gravel, rock, or bare soil.
- No plants under vent openings, windows, or against siding. Embers land here and find fuel.
- No wood fencing attached to the house. If a fence must attach, the last 5 feet must be metal or non-combustible.
- No firewood, plastic furniture, doormats, brooms, or trash bins stored in this zone.
- Well-irrigated potted plants (low, spaced) are fine — some cities are stricter; check your ordinance.
California's AB-3074 phased Zone 0 requirements in from 2025. Insurers already inspect it.
Zone 1: 5-30 feet, lean/clean/green
- Lean: Little vegetation to burn. Shrubs pruned and spaced at least 3x their height apart.
- Clean: Dead plants, dry leaves, pine needles, dropped fronds — all removed. Every season.
- Green: What remains is irrigated and healthy. A dry lawn is fuel; a green one is a firebreak.
- Trees spaced at least 10 feet crown-to-crown. Prune branches within 10 feet of the roof, chimney, or power lines.
- No wood decks with combustible material stored underneath.
Zone 2: 30-100 feet, reduce fuel load
- Reduce continuous fuel that could carry a running fire toward the house.
- Space larger trees so canopies don't touch.
- Remove ladder fuels — the shrubs and small trees under mature trees that let a ground fire climb into the canopy.
- Grass to under 4 inches.
- Firewood stacks and propane tanks moved here, not stored against the house.
Plants that behave better in fire
Every region has a list of fire-resistant plants — high moisture content, low resin, low volatile oils. Some general categories:
- Groundcovers: ice plant, sedum, myoporum, native grasses maintained irrigated.
- Shrubs: California lilac (Ceanothus varieties), currant, coffeeberry, hebe.
- Trees: madrone, California black oak, live oak — hardwoods with high moisture content.
Plants to remove near the house: juniper (a signature "gasoline plant"), rosemary in heavy blocks, dry ornamental grasses, and any conifer within 30 feet of the structure.
Fences, decks, and outbuildings
- Wood fence attached to a wood house is a wick. Replace the final 5 feet at the house connection with metal.
- Wood decks: no storage underneath; box in with fire-resistant material or replace boards with composite rated for wildland-urban interface.
- Sheds and detached garages within 30 feet: harden the same way as the house, or move them.
Maintenance is the whole game
Defensible space is a maintenance regime, not a one-time project. A single unraked fall of pine needles undoes years of clearing. Twice a year — spring after growth, fall before fire season peak — mow, prune, rake, and clean gutters. Photograph the finished result for insurance and permit files.
Documentation and insurance
Some carriers offer mitigation discounts for verified defensible space and home hardening — often 5-15% off the wildfire portion of the premium. Photograph zones after each maintenance cycle, keep receipts for tree work, and ask your carrier or a broker whether documented compliance changes your rate.
Common questions
- What is defensible space?
- A managed buffer of vegetation and combustibles around your home, designed so that a wildfire arriving at the property line runs out of fuel before it reaches the structure. Split into three zones: 0-5 ft, 5-30 ft, and 30-100 ft.
- Is defensible space required by law?
- In California and much of the Western US, yes, at least at the 100-foot standard. California AB-3074 phased in Zone 0 (the 0-5 ft ember-resistant zone) with specific requirements. Check your local ordinance.
- Does defensible space actually work?
- In modeled and post-fire studies, well-maintained defensible space combined with a hardened structure can reduce home-loss probability by an order of magnitude. It is one of the highest-ROI wildfire actions a homeowner can take.
- Can I still have a nice yard?
- Yes. 'Fire-resistant' does not mean 'no plants.' It means the right plants in the right places — irrigated, low-growing, well-spaced, and never touching the house.
- Who enforces defensible space?
- In California, CAL FIRE, local fire departments, or defensible-space inspectors. In other states, local fire marshals. Insurers increasingly inspect independently and use compliance as a rating factor.
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