Building an ADU in a Bay Area Fire Zone: Zone 0, Berkeley and the Oakland Hills

When people say "fire zone," they usually mean a Fire Hazard Severity Zone mapped by the State Fire Marshal, rated Moderate, High or Very High. Cities also define a wildland-urban interface (WUI) area where stricter building and defensible-space rules apply. You can look up your address on the state's Fire Hazard Severity Zone viewer.

In Berkeley, the WUI covers the High and Very High zones in the hills, including the Panoramic Hill and Grizzly Peak mitigation areas; the flatlands are outside it. In Oakland, the WUI is the Very High Fire Hazard Severity Zone in the hills.

Zone 0 is the first 5 feet around a building, where embers can most easily ignite a home. California's Board of Forestry approved statewide Zone 0 rules on August 19, 2026, under AB 3074 and SB 504. As of the Board's latest update they were still in final review by the Office of Administrative Law.

Once final, the rules apply right away to new construction. Cities that run their own fire services may need to adopt them locally. In Oakland, existing homes get a phased timeline: the first phase, like clearing firewood, mulch and dead plants within 5 feet, within three years, and the second, covering items like fences, gates and sheds, within five.

For a new ADU, Zone 0 is mostly a design question. If you plan for it from the start, the 5 feet around the unit becomes gravel, pavers or a concrete path instead of a rework later.

Berkeley adopted its own WUI code in 2025, and it's stricter than the statewide baseline in a few ways that matter for ADUs.

• Zone 0 is already in force in the Panoramic Hill and Grizzly Peak areas. Keep the first 5 feet free of combustible material, including under decks. Hardscape is fine, and small potted plants are allowed.
• Trees and fences. Canopies need to stay 6 feet above the roof, 10 feet from chimneys and 5 feet away horizontally. An attached wood fence needs a 5-foot noncombustible section next to the building, and new combustible fencing can't go within 5 feet.
• Outbuildings. A shed or accessory building inside Zone 0 has to be built to the state's wildfire construction standards.
• New buildings. Class A roofs, no wood shakes, and utility conduits run underground.
• Panoramic Hill. New construction also needs sprinklers, a fire warning system with an exterior alarm, a 3/4-inch hose bib before framing and a 75-foot hose on site.

About 1,400 properties fall under Berkeley's Zone 0 rules. The city began inspections in May 2026, gives owners 60 days to fix issues, and fines start at $100.

Oakland requires new construction in its WUI to use a Class A roof, fire-resistant siding and ember-resistant metal mesh vents. The Oakland Fire Department inspects WUI properties every year and is adding Zone 0 to those inspections, starting on an educational basis.

Hillside lots add their own challenges: retaining walls, access for equipment and drainage. Our hillside ADU guide and Oakland ADU builder page go deeper.

Yes. California's wildfire standards govern the outside of the building: the roof, siding, vents, decks and the space around it. They don't ban wood framing. Type Five builds every ADU on site with conventional wood framing and uses a fire-resistant exterior package on lots in fire zones.

Our Hermosa guesthouse in Orinda and Caldwell ADU in Oakland both sit in WUI zones and use that fire-resistant material package.

• Plan Zone 0 into the site plan. Put paths, gravel or pavers in the first 5 feet instead of planting beds and bark.
• Keep decks simple. Under-deck space has to stay clear in Berkeley's Zone 0 areas, so low decks or concrete patios are easier to maintain.
• Detail fences where they meet the ADU. A noncombustible gate or fence section next to the building avoids a fix later.
• Budget for it. Fire-rated materials and site work add cost; our Bay Area ADU cost guide shows how fire zone requirements fit into a full budget.