If your home sits in a California Fire Hazard Severity Zone, new state law now requires specific changes to the 5-foot perimeter around your property. Here's your plain-language guide to AB 3074, SB 504, and AB 1455.
Zone Zero is the ember-resistant defensible space zone within 0–5 feet of any structure in a California Fire Hazard Severity Zone. Established by AB 3074 in 2020 and strengthened by SB 504 (2024) and AB 1455 (2025), it is now moving into active enforcement. Wildfires rarely ignite a home directly. They ignite things near the home. Zone Zero eliminates that pathway.
Zone Zero Explained
Zone Zero is a new category of defensible space immediately surrounding any structure in a California Fire Hazard Severity Zone. Unlike existing defensible space law (Zones 1 and 2, covering 5–100 feet), Zone Zero has its own compliance timeline and enforcement mechanism.
Research consistently shows that embers, not direct flames, cause most structure ignitions in wildfires. Zone Zero eliminates the fuel sources closest to your home.
Required Changes
Key Deadlines
Phase 1: Est. 2027–2028
3 years after final rule adoption
Clearing and removal: mulch, gutters, eaves, tree trimming, 1-foot foundation zone
Phase 2: Set by local AHJ
Up to 5 years from adoption
Replacement: fencing, decking, vents, outbuildings. No new combustible fences immediately upon adoption.
New construction:Zone Zero required immediately upon adoption. No grace period.
Landscaping & Vegetation
Bark mulch, wood chips, dead vegetation, and all combustible ground cover must be removed. A 1-foot vegetation-free zone at the foundation is required.
Phase 1Gutters, Eaves & Roof
All combustible debris must be removed from gutters, roof surfaces, and eave areas. Ember-resistant gutter guards are recommended for ongoing compliance.
Best PracticeVents & Openings
Foundation and attic vents are a leading ember entry point. Ember-resistant mesh covers (1/16 inch max) are strongly recommended and may be required by local AHJ.
Phase 2Fences & Gates
No new combustible fencing may be installed immediately upon adoption. Existing wood and vinyl fencing within Zone Zero must be replaced with non-combustible materials.
Phase 2Decks & Patios
Combustible decking within Zone Zero must be replaced. Under-deck space must be enclosed or kept permanently clear. Most composite decking does not comply.
Phase 2Sheds & Outbuildings
All accessory structures within Zone Zero must have ignition-resistant exterior materials. This includes garden sheds, pool equipment enclosures, and detached garages.
Zone Zero enforcement timelines and Phase 2 deadlines vary by county. Select your county to see local compliance requirements, your Authority Having Jurisdiction, and licensed contractors serving your area.
Los Angeles
500,000+ homes at risk
San Diego
Very High FHSZ
Ventura
Very High FHSZ
Orange
Very High FHSZ
Riverside
Very High FHSZ
San Bernardino
Very High FHSZ
Santa Barbara
Very High FHSZ
Alameda
Very High FHSZ
Final rules expected late 2026
Contractor availability in high fire risk areas is limited. Homeowners who act before final rules are adopted will have more choices, better pricing, and no deadline pressure.