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Defensible space zones 0/1/2 — California's 100-foot rule + what works in practice

Wildfire risk isn't just hazard-zone classification — it's also what you do in the 100 feet around your house. Defensible space is the most actionable wildfire-mitigation step a homeowner can take.

Published 2026-04-25 · Last reviewed 2026-07-03 · methodology

Zone 0 — 0 to 5 feet from the structure (ember-resistant)

California law (AB 3074) — phasing in 2025-2026 — requires this zone to be ember-resistant.

What this means: NO mulch, NO wooden fences attached to the house, NO firewood storage, NO juniper / cypress / other resinous shrubs.

What's allowed: bare soil, hardscape (concrete, gravel, stone), well-watered low-flammability ground cover (succulents, lawn).

Roof + gutters: keep clear of leaves/needles. This is where embers settle and ignite the structure.

Vents: 1/8-inch metal mesh (ember-resistant). Common attic-vent failure mode: 1/4-inch screens that admit embers.

Zone 1 — 5 to 30 feet from the structure (lean, clean, green)

Lean: limit shrub mass; keep plantings discontinuous (don't let fuel ladder up to tree canopies).

Clean: remove dead branches, leaves, pine needles regularly.

Green: irrigate; keep grass cut <4 inches.

Tree spacing: minimum 10 feet between canopies; 15 feet from structure for any tree.

Firewood + propane tanks: store in Zone 2 if possible, never in Zone 0.

Zone 2 — 30 to 100 feet (reduced fuel)

Allow native vegetation but reduce density. Goal: break the fuel continuity so a wildfire's intensity drops as it approaches the structure.

Tree spacing: 6-foot minimum gap between canopies on flat ground; more on slopes (slope drives fire upward + faster).

Slope multipliers: defensible space distance EXTENDS on the downhill side because fire moves uphill. CA Public Resources Code adjusts for slope.

Goal at the 100-ft boundary: a wildfire arriving here should be a surface fire, not a crown fire.

Insurance + appraisal implications

California's FAIR Plan + most private wildfire insurers now require defensible-space inspections. Failure = denied coverage / non-renewal.

Some carriers offer discounts for hardened homes (Class A roof, ember-resistant vents, defensible space verified).

Insurance score may improve $200-2,000/year savings depending on county + coverage.

If you're in a high-WHP zone (see /topic/wildfire-risk/) and your home has not been hardened: shop insurance NOW. The CA non-renewal moratorium is changing year-by-year.

States with similar requirements

California — most stringent (PRC 4291).

Oregon — SB 762 wildfire-hazard map + similar defensible-space requirements in high-hazard zones.

Colorado — county-by-county; many WUI counties (Boulder, Larimer, Jefferson) have local codes.

Washington, Arizona, New Mexico, Utah, Nevada, Idaho, Montana, Wyoming — variable; check local fire-protection-district rules.

What zipradar shows

USFS Wildfire Hazard Potential at ZIP level — the regional risk score (Class 1=low to Class 5=very high). See /topic/wildfire-risk/[zip]/.

Defensible space is parcel-level + behavioral, not in our 12-dimension federation.

Combine: high WHP + your home has not been hardened = high P0 priority before fire season.