Zone 0: California's Ember-Resistant Defensible Space Rule

What is Zone 0?

Zone 0 is the 0–5 foot ember-resistant zone right against a structure — the innermost defensible space zone in California. The idea is simple: keep anything that can catch an ember out of the first 5 feet around the building. Wind-driven embers, not direct flame, are the leading cause of homes lost in wildfire, and they collect against walls, under decks, and in mulch beds. Zone 0 was directed by Assembly Bill 3074 (2020), which tasked the California Board of Forestry and Fire Protection with defining the standard (https://bof.fire.ca.gov). CAL FIRE's Ready for Wildfire program publishes homeowner guidance for it (https://www.readyforwildfire.org). This is fuel reduction at the closest range — defensible space prep, not a guarantee of any outcome.

What is restricted in the 0–5 ft zone?

Zone 0 targets the ignitable material that embers catch against the structure:

• Combustible bark and wood mulch — replaced with gravel, decomposed granite, pavers, or bare mineral soil
• Flammable vegetation planted against siding — shrubs, ornamental grasses, and dead plant material in the band
• Stored firewood, lumber, and fuel cans staged against or under the structure
• Combustible fences and gates that attach directly to the home — a wood fence touching the wall is an ember pathway straight to the structure
• Stored items under decks and in the 0–5 ft band — patio furniture cushions, brooms, door mats, and debris
• Leaf and needle litter on the ground, in gutters, and on the roof edge within the zone

How does the Zone 0 rollout work?

AB 3074 set up a phased approach rather than an overnight switch. As adopted by the California Board of Forestry and Fire Protection, the regulation applies to new construction in High and Very High Fire Hazard Severity Zones first, with existing structures phased in afterward. Because the exact effective dates are set by the Board's adopted regulations and can change, we don't quote a hard date here — confirm current applicability for your parcel at bof.fire.ca.gov and readyforwildfire.org. The practical takeaway: if you're building new in a high-hazard zone, plan for Zone 0 now; if you own an existing home in one of those zones, expect the standard to reach you and start clearing the 0–5 ft band early.

How Zone 0 pairs with Zones 1 and 2

Zone 0 is the innermost band of California's three-zone defensible space framework. Each zone does a different job, and they only work as a system. Zone 0 keeps embers from igniting against the structure; Zone 1 (5–30 ft) keeps fire from reaching the building; Zone 2 (30–100 ft, or to the property line) slows and lowers an approaching fire. The table below shows what belongs in each.

Zone 0 and home hardening work together

Zone 0 manages the space around the structure; home hardening upgrades the structure itself. The two reinforce each other. A hardened home with embers piling up in bark mulch against the siding is still exposed; a clean Zone 0 around a home with open eave vents still lets embers inside. Treat them as one project.

• Ember-resistant attic, eave, and foundation vents (1/8-inch metal mesh or listed ember-resistant vents)
• Class A roofing and a clean roof and gutter line free of needles and leaves
• Enclosed or fire-resistant eaves, soffits, and the underside of decks
• Noncombustible siding and a 6-inch noncombustible base at the bottom of walls where feasible
• Dual-pane or tempered windows, which resist radiant-heat failure that lets embers inside

What a clearing crew handles vs. what the owner does

Zone 0 is close-in detail work — it's usually the owner, a landscaper, or a handyman who swaps mulch for gravel, moves the woodpile, and clears under the deck. An earthwork and clearing crew like NorCal Earthworks does the heavier work that supports it: fuel reduction and brush reduction in Zones 1 and 2, removing the dense vegetation and ladder fuels that feed a fire toward the structure, clearing driveway and access routes for fire apparatus, and hauling or chipping the cleared material. We can't certify your property as compliant — only a CAL FIRE inspector signs off on defensible space — but we get the parcel into the shape the standard describes.

How to get started on Zone 0

• Walk the first 5 feet around every structure and list every combustible item touching or near the wall
• Replace bark mulch in that band with gravel, decomposed granite, or pavers
• Move firewood, lumber, and fuel storage well away from the structure
• Clear stored items and debris out from under decks and porches
• Address combustible fencing where it attaches to the home — swap the attaching section for metal or add a noncombustible gap
• Schedule Zone 1 and Zone 2 fuel reduction so the outer buffer supports the work you did in Zone 0

Sources and references

• CAL FIRE Ready for Wildfire (defensible space and Zone 0 guidance): https://www.readyforwildfire.org
• California Board of Forestry and Fire Protection: https://bof.fire.ca.gov
• CAL FIRE Defensible Space: https://www.fire.ca.gov/dspace
• Assembly Bill 3074 (2020) — defensible space / Zone 0 direction (California Legislature): https://leginfo.legislature.ca.gov/

Ready to clear the buffer around your home?

We handle the fuel reduction and brush reduction in Zones 1 and 2 that back up your Zone 0 work — plus access and driveway clearing. Send the address and a few photos of the property edges and we'll scope it.