Zone 0 defensible space: the complete California homeowner guide.

What is Zone 0?

Zone 0 is the first 5 feet from every wall of every structure on a property in a California Very High Fire Hazard Severity Zone (VHFHSZ). Under Assembly Bill 3074 — passed in 2020 and signed into California Public Resources Code §4291 — that 5-foot perimeter must be ember-resistant. In practical terms, nothing inside the zone should be able to catch fire from a wind-blown ember and ignite the building.

Zone 0 sits on top of the existing California defensible space rules (Zone 1: 5–30 ft "lean, clean & green"; Zone 2: 30–100 ft "reduce fuel"). It is the strictest of the three zones and the one wildfire science says matters most for whether a home survives an ember storm.

See also: California Defensible Space Zones: Zone 0, Zone 1, and Zone 2 Explained for the full three-zone breakdown.

Why Zone 0 exists

Post-fire research from the Insurance Institute for Business & Home Safety (IBHS), NIST, and CAL FIRE consistently shows the same finding: most homes that burn in a wildfire are not consumed by direct flame contact. They are ignited by embers — small burning fragments that travel ahead of the fire front on the wind, sometimes a mile or more from the active flame. These embers land in vulnerable spots adjacent to the home: pine needles in a gutter, a bark-mulch bed against the foundation, a wood fence attached to the wall.

The 5-foot perimeter targets exactly those ignition points. If nothing within 5 feet of the home can ignite from an ember, wildfire's primary path to the structure is cut off — even if the fire passes through the rest of the property.

See: How Zone 0 Stops Wildfire: The Science of Ember Ignition.

The 12 Zone 0 requirements, at a glance

Zone 0 is implemented as a 12-item checklist. Each one targets a known ember-ignition mode. The list below is the working version homeowners and inspectors use today — based on the Board of Forestry's draft framework and the publicly available CAL FIRE guidance.

1. No combustible vegetation within 5 ft. No plants, shrubs, mulch, or groundcover that can burn within 5 ft of any wall.
2. Non-combustible ground cover only. Gravel, pavers, concrete, or bare soil within the 5-ft zone (no bark mulch or wood chips).
3. No wood fencing attached to home. Wooden fences within 5 ft of structure replaced with metal or masonry, or have a non-combustible break.
4. Firewood / lumber stored 30+ ft away. No firewood piles, propane tanks, or lumber within 30 ft of any structure.
5. Roof and gutters clean. No leaves, pine needles, or debris in gutters, on roof, or in eaves.
6. No combustible outdoor furniture in zone. Wooden patio furniture, doormats, decorations not placed within 5 ft of walls.
7. Tree branches trimmed 10+ ft from structures. Including chimneys and over the roof.
8. Dead vegetation removed. No dead plants, dry grass, or dead branches anywhere on property.
9. Under decks and stairs clear. No vegetation, storage, or combustibles under any deck, porch, or stairs.
10. No combustible plants in containers. Planters and pots within 5 ft contain only non-combustible material or fire-resistant plants.
11. Vents covered with 1/8" mesh. All attic, foundation, and eave vents have 1/8-inch metal mesh covers.
12. Doormats are fiberglass / non-combustible. No coconut/coir/woven natural-fiber doormats at any entrance.

For the full materials and building-code spec behind each item, see The 5-Foot Ember-Resistant Zone: Building Code, Materials, and Compliance.

Who has to comply

AB 3074 Zone 0 applies to structures in designated Very High Fire Hazard Severity Zones. The Office of the State Fire Marshal maintains the official Fire Hazard Severity Zone map for California.

California counties with substantial VHFHSZ acreage include Los Angeles, San Diego, Orange, Riverside, San Bernardino, Ventura, Santa Barbara, Sonoma, Napa, Marin, Alameda, Contra Costa, Placer, El Dorado, Nevada, Butte, Shasta, Tulare, Mariposa, Lake, Mendocino, and many others. Many local jurisdictions are also adopting Zone 0 for High and Moderate hazard zones on top of the state baseline.

For the state-specific picture — county breakdowns, ordinance variations, California fire ecology — see Zone 0 in California: AB 3074 Defensible Space Requirements.

Where the regulations stand right now

AB 3074 became law on January 1, 2021. The Board of Forestry has been working on the implementing regulations ever since — through three missed deadlines, a Governor's Executive Order, and a recently-resumed Zone 0 Committee process. Current expected adoption is mid-to-late 2026. When the regulations are adopted, new construction in VHFHSZ areas must comply immediately and existing homes are expected to be phased in starting 2027.

For the full rulemaking history, statute text, penalty structure, and current state — see Zone Zero Regulations: Current Status of California Defensible Space Rules and AB 3074 Explained: California's Defensible Space Law.

The bigger urgency: insurance

State enforcement is still ramping. Insurance carriers, however, are already enforcing Zone 0 today. Farmers, State Farm, Allstate, USAA, and other California carriers are using Zone 0 compliance — observable from aerial imagery on renewal — as a factor in non-renewal, premium pricing, and claim decisions. The most common path to a Zone 0 problem in 2026 is not a CAL FIRE inspector at the door; it is a non-renewal letter from your insurer.

See: Farmers, State Farm, and the California Defensible-Space Crackdown.

What an inspection looks like

Four kinds of inspection can encounter Zone 0:

• CAL FIRE annual defensible space inspections — in most participating counties, April through September.
• Local fire department inspections — city or county programs on top of or in place of CAL FIRE.
• Insurance carrier inspections — typically aerial imagery, occasionally an in-person inspector at renewal or new application.
• Point-of-sale inspections — increasingly common when listing a home in a VHFHSZ.

For each one — what they check, how to prepare, what happens if you fail — see Defensible Space Inspection: What to Expect and How to Pass.

How much it costs

A typical California Zone 0 project for a standard single-family home runs $3,500 to $12,000. Big drivers of variation are home value (luxury-market labor premium), lot size (more vegetation), how much wood fencing currently touches the house, and how many vents need retrofit.

For the per-item pricing, regional variation, hidden costs, and financing options, see Zone 0 Defensible Space Cost: California Homeowner Pricing Guide.

How to start

The cheapest, lowest-stress version of Zone 0 compliance is the one done on your schedule rather than someone else's. The sequence we recommend:

1. Run the free 60-second check. We turn the 12-item Zone 0 framework into a personalized report with gap-by-gap detail and an estimated cost range. Start the check →
2. Handle the easy items in a weekend. Gutter and roof cleaning, doormat replacement, moving firewood, removing dead vegetation. Most homeowners can knock out 4–6 items themselves for under $500 in materials.
3. Plan the bigger items. Wood-fence break or replacement, tree work, vent retrofit. These usually need a contractor — but they don't all have to happen at once.
4. Document everything. Before-and-after photos, dated. Save receipts. This documentation becomes critical at your next insurance renewal or property sale.

Related guides

Every cluster article on this site goes deep on one slice of Zone 0. The full hub:

• Zone 0 in California: AB 3074 Defensible Space Requirements
• Zone Zero Regulations: Current Status of California Rules
• Defensible Space Inspection: What to Expect and How to Pass
• California Defensible Space Zones: Zone 0, Zone 1, and Zone 2 Explained
• How Zone 0 Stops Wildfire: The Science of Ember Ignition
• Zone Zero Landscaping: Fire-Resistant Design for the 5-Foot Perimeter
• The 5-Foot Ember-Resistant Zone: Building Code, Materials, and Compliance
• Zone 0 Defensible Space Cost: California Homeowner Pricing Guide
• AB 3074 Explained: California's Defensible Space Law

Status as of May 2026. The Board of Forestry rulemaking continues to evolve — this hub is updated when material changes occur. Sources: California Board of Forestry & Fire Protection, California Public Resources Code §4291, CAL FIRE public documents, Office of the State Fire Marshal Fire Hazard Severity Zone maps.