California defensible space zones: Zone 0, Zone 1, and Zone 2 explained.

The three-zone framework

California defensible space law (Public Resources Code §4291) requires 100 feet of defensible space around any habitable structure in a designated fire hazard area in California. That 100 feet is split into three concentric zones, each with progressively stricter requirements as you move toward the structure.

The full framework, in order from outermost to innermost:

• Zone 2 (30–100 ft) — Reduce Fuel Zone
• Zone 1 (5–30 ft) — Lean, Clean & Green Zone
• Zone 0 (0–5 ft) — Ember-Resistant Zone

Zone 0 — Ember-Resistant Zone (0–5 ft)

The newest of the three zones, created by Assembly Bill 3074 (signed 2020, effective January 1, 2021). Zone 0 is the first 5 feet from every wall of every structure.

The operating principle: nothing inside the 5-foot perimeter should be able to ignite from a wind-blown ember and then ignite the structure. This is the strictest zone because it's the one where ember-driven ignition is most likely.

What's required:

• No combustible vegetation (no plants, shrubs, or groundcover that can burn).
• Non-combustible ground cover only — gravel, decomposed granite, pavers, concrete, bare soil, or other approved materials.
• No wood fencing attached directly to the structure; metal or masonry breaks required where wood fencing meets a wall.
• No firewood piles, propane tanks, lumber, or other stored combustibles within the zone (and 30+ feet away from any structure).
• Roofs and gutters kept clear of leaves and debris.
• No combustible outdoor furniture, doormats, or decorations.
• Container plants only fire-resistant species in non-combustible containers.
• 1/8-inch metal mesh over vents (attic, foundation, eave).
• Non-combustible doormats at all entrances.

For the full materials and code spec, see The 5-Foot Ember-Resistant Zone: Building Code, Materials, and Compliance. For implementation status and rulemaking timeline, see Zone Zero Regulations.

Zone 1 — Lean, Clean & Green Zone (5–30 ft)

Zone 1 covers the next 25 feet outward from Zone 0. The operating principle: vegetation is allowed, but it must be managed so it can't carry fire to the structure or to Zone 0.

Three words capture Zone 1:

• Lean — vegetation kept low and thinned. No ladder fuels (shrubs that let fire climb from the ground to the tree canopy).
• Clean — dead leaves, pine needles, dead branches, and other dry plant material removed regularly.
• Green — what does remain is healthy, well-watered, and fire-resistant.

What's required:

• Maintain horizontal spacing between trees and shrubs (typically 6–18 feet depending on slope).
• Maintain vertical spacing — keep ladder fuels removed underneath tree canopies.
• Remove dead plant material across the zone.
• Keep tree canopies trimmed back from structures (10+ ft clearance) and from each other.
• Keep grass mowed to 4 inches or shorter.
• Remove combustible debris and storage.

Zone 1 has been California law since well before AB 3074. The requirements have evolved over time as fire science has improved, but the underlying lean-clean-green concept dates back decades.

Zone 2 — Reduce Fuel Zone (30–100 ft)

Zone 2 is the outermost ring — 30 to 100 feet from any structure. The operating principle here is fuel modification, not fuel removal. A wildfire approaching from this distance should encounter materially less fuel than the surrounding wildland, slowing it down and reducing flame height before it reaches Zone 1.

What's required:

• Mow grass to 4 inches or shorter.
• Create horizontal spacing between shrubs and trees, with spacing based on slope (steeper slopes require wider spacing).
• Remove ladder fuels — vegetation that allows fire to climb from the ground to the tree canopy.
• Keep tree canopies separated — typically by at least 10 feet at maturity.
• Remove dead plant material.

Zone 2 is the least restrictive of the three zones. You can keep trees, shrubs, and other vegetation — you just have to manage them so they can't carry fire toward the home at full intensity.

How the zones work together

The three zones form a defense-in-depth system. Each zone targets a different fire behavior:

• Zone 2 reduces flame intensity by removing fuel — the fire arriving at Zone 1 is less intense than it would be without Zone 2.
• Zone 1 deprives the fire of the connected, unbroken vegetation it needs to travel as a continuous flame front toward the structure.
• Zone 0 stops the ember-driven ignition path — the most common way California homes burn — by removing every nearby surface an ember could land on and ignite.

The reason all three zones are required together is that any one of them alone has a failure mode. Zone 2 alone allows Zone 1 vegetation to carry fire to the house. Zone 1 alone doesn't protect against embers landing in mulch at the foundation. Zone 0 alone doesn't help when a 40-foot flame front arrives from 50 feet away. Together they cover the realistic spectrum of wildfire behavior.

Property-line edge cases

Two common situations require special handling:

• Your property is smaller than 100 feet from the structure. Maintain defensible space out to your property line. You cannot trespass to maintain defensible space on a neighbor's land — but you can request that your neighbor maintain their own.
• Multiple structures on one parcel. Each habitable structure gets its own 100-foot defensible space ring. Where rings overlap, the stricter requirement applies to the overlap.

Inspection across all three zones

California defensible space inspectors evaluate all three zones together. A typical CAL FIRE annual inspection walks the property perimeter from Zone 0 outward, noting issues at each layer. A property can pass Zones 1 and 2 but fail Zone 0 — the inspector records each zone's status separately.

For the inspection process in detail, see Defensible Space Inspection: What to Expect and How to Pass.

Start with the easiest zone

Most homeowners can get all three zones into compliance over a single season. The cheapest, fastest progress usually comes from:

1. Zone 2 fuel reduction — typically a single tree-work visit and a mowing cycle.
2. Zone 1 cleanup — dead-material removal, a weekend of trimming, and ongoing maintenance.
3. Zone 0 hardening — the most material-heavy of the three, but the most impactful for wildfire survival and insurance.

Run the free 60-second Zone 0 readiness check to see where your perimeter stands today: Start the check →

Sources: California Public Resources Code §4291; AB 3074 (2020); California Board of Forestry & Fire Protection public documents; CAL FIRE Ready for Wildfire defensible space guidance.