What Is Zone 0 — and What Do I Actually Have to Do?

Zone 0 is generating more confusion — and more urgency — than any other wildfire compliance topic in San Diego County right now. Most homeowners have heard the term. Very few understand what it actually requires, why the 5-foot standard exists, or what specifically needs to change on their property. This page answers all three.

What Zone 0 is

Zone 0 is the 0–5 foot buffer immediately surrounding your home, attached structures, decks, and stairs. Its legal name is the ember-resistant zone. It was established under AB 3074 (2020) as a statewide standard, and it is separate from — and in addition to — the Zones 1 and 2 defensible space requirements that already exist under PRC 4291.

The name tells you what Zone 0 is designed to do: resist embers. Unlike Zone 1 and Zone 2, which reduce the fuel available to carry fire toward your structure, Zone 0 addresses the ignition pathway that destroys most homes in California wildfires — not the fire front, but embers that land directly against or near the structure and ignite it from close range.

Why Zone 0 exists — the fire science behind it

Research by Dr. Jack Cohen at the USFS Missoula Fire Sciences Lab established that most homes in wildfire don’t ignite from direct flame contact with the fire front. They ignite from embers — firebrands carried by wind that land against combustible material in the home’s immediate surroundings and start a small fire that grows. The fire front doesn’t need to reach the structure if the structure’s own perimeter provides the final ignition pathway.

Field documentation from California fires confirms this. In the 2007 Witch Creek Fire in San Diego’s East County, two out of three homes were ignited by wind-dispersed embers, not the fire front. IBHS research consistently shows that a non-combustible 0–5 foot buffer around a structure materially reduces its ignition risk by eliminating the landing zone where embers can sustain combustion.

Zone 0 exists because the 5 feet around your home are more important to your home’s survival than the 95 feet beyond it.

Where Zone 0 applies — state vs. San Diego County

At the state level, AB 3074 directed the Board of Forestry to create Zone 0 regulations, and Governor Newsom’s Executive Order N-18-25 (February 2025) directed the Board to finalize those regulations by December 31, 2025. California is moving toward statewide Zone 0 enforcement for existing homes — February 2027 is the planning deadline homeowners should treat as real when preparing existing structures. Verify current statewide enforcement status directly with CAL FIRE at (619) 579-3200 or fire.ca.gov.

In San Diego County, you don’t need to wait for the state. Zone 0 is already codified and enforceable under San Diego County Ordinance 10927 Section 4907.9.1 for properties in unincorporated areas. If your property is in unincorporated San Diego County — Lakeside, Alpine, Ramona, Julian, Fallbrook, Pine Valley, Descanso, Valley Center, and surrounding communities — Zone 0 compliance is a current requirement, not a future planning goal. CAL FIRE San Diego Unit inspectors and local fire protection districts flag Zone 0 violations during defensible space inspections today.

Not sure whether your property is in the SRA or LRA? See SRA vs. LRA Explained. Either way, Zone 0 applies to you if you’re in unincorporated San Diego County.

What Zone 0 specifically requires

Ground surface

San Diego County Ordinance 10927 requires the ground within 5 feet of your home, deck, stairs, and attached structures to be covered with continuous noncombustible material.

Materials that satisfy Zone 0: concrete, pavers, gravel, decomposed granite (DG), bare mineral soil.

Materials that do not satisfy Zone 0: bark mulch, wood chip mulch, rubber mulch (regardless of fire-resistance claims on the packaging), shredded wood of any kind, and organic ground cover. Combustible mulch against a foundation is the single most common Zone 0 violation on East County properties — and one of the cheapest to correct.

Vegetation

Zone 0 must be free of live and dead plant material that would provide an ignition pathway to the structure. Ornamental grasses, drought-stressed plantings, and accumulated dead material in place are violations under current local requirements.

High-resin species — rosemary, juniper, manzanita, lavender — are among the highest-ignition-risk plants when placed near a structure. Fire behavior research documents that these species ignite readily from ember contact and can sustain combustion long enough to ignite adjacent structural materials. They belong outside Zone 0 entirely.

Fencing

Wood fencing attached to your home or within the Zone 0 perimeter is a violation under San Diego County Ordinance 10927. Wood acts as a direct fire wick into the structure. The fix is a noncombustible transition section — metal or masonry — where the fence meets or enters Zone 0. A full fence replacement is not required, just the transition section at the boundary.

Decks and under-deck clearance

Attached decks are part of the Zone 0 perimeter. Combustible materials stored under decks — firewood, furniture, equipment, organic debris — create an enclosed combustion chamber directly adjacent to the structure. Under-deck spaces must be clear or enclosed with noncombustible material.

Gutters

Gutters filled with leaf litter, pine needles, or debris are one of the primary ember ignition points identified in structure-loss research. Metal gutters with noncombustible gutter guards are the preferred standard. At minimum, gutters must be cleared before fire season and maintained throughout.

Zone 0 and Zones 1 and 2 — how they work together

Zone 0 addresses ignition at the structure. It does not replace Zones 1 and 2 — it adds to them.

Zone 1 (the area from Zone 0 out to 30 feet) reduces the fuel available to carry fire toward your home — dead material removed, grass cut short, no ladder fuels connecting ground vegetation to tree canopy. Zone 2 (30–100 feet) further reduces fuel continuity across the broader property. Both are required under PRC 4291 and the San Diego County Fire Code. Zone 0 is the highest priority for ember ignition prevention. Zones 1 and 2 are what slow or redirect a fire front before it reaches your structure.

A home with a perfect Zone 0 but no Zone 1 or 2 clearance is still a fire risk. A home with good Zone 1 and 2 but a combustible Zone 0 can still ignite from embers before the fire front arrives. All three zones work together.

Zone 0 and insurance

Zone 0 compliance is one of the Immediate Surroundings factors in California’s Safer from Wildfires discount framework under 10 CCR § 2644.9. Documented Zone 0 work — noncombustible ground surface, combustible mulch removed, wood fence transition installed, gutters maintained — can support a wildfire risk score reconsideration request with your insurer. Documentation is the critical variable: photos with dates, a written record of what was done and when. Without it, completed work doesn’t count in an underwriting review.