Wildfire decking rules for new buildings in fire hazard severity zones (deck surfaces within 10 ft of the building).
Whether those rules reach a replacement deck or addition on an older home. Local amendments vary.
The Board of Forestry's Zone 0 rules: adopted Aug 19, 2026, withdrawn from OAL review in early September 2026.
The 10-foot decking rule
California's wildfire building rules, long known as Chapter 7A and, for houses, California Residential Code section R337, require the walking surface of decks, porches, balconies and stairs within 10 feet of the building to be one of these:
- Material that meets the decking performance tests (State Fire Marshal Standard 12-7A-4, or ASTM E2632 with ASTM E2726).
- Ignition-resistant material.
- Exterior fire-retardant-treated wood.
- Noncombustible material.
2025 code update: in the 2025 code cycle (effective January 1, 2026), California moved the Chapter 7A / R337 content into the new California Wildland-Urban Interface Code (Title 24, Part 7). The decking surface provisions are in its Chapter 5, Section 504.7.3. Your building department will tell you which edition and section governs your permit.
At the state level these rules were written for new buildings in fire hazard severity zones. Additions and remodels of older homes have not automatically had to comply, but cities and fire districts can adopt stricter local amendments. Ask your building department and fire district before you choose decking.
Material options
| Option | What to check |
|---|---|
| Listed composite or PVC boards | Some lines are listed as passing the SFM 12-7A-4 / ASTM E2632 + E2726 tests; many are not. Get the listing for the exact product line. |
| Fire-retardant-treated (FRT) wood | Must be exterior-rated FRT, since interior FRT treatments leach out outdoors. Confirm the product and its finishing requirements. |
| Noncombustible surfaces | Some aluminum decking systems, tile or concrete over a suitable structure. Heavier detailing and cost. |
| Ignition-resistant materials | Products that meet the code's ignition-resistant definition after weathering tests. Check the documentation. |
The State Fire Marshal's Building in the Wildland page links to its tested-materials resources. Composite is covered in more depth on composite decks and the composite vs wood guide.
Request a fire-zone deck quoteClearing beneath and around decks
Embers collect under and against decks. Whatever the code status, fire districts consistently advise keeping the area under the deck clear of firewood, lumber, plastic storage, dry leaves and plants, and keeping the first few feet around the house hard-surfaced or bare. Gravel under a low deck and screened or enclosed undersides are common choices.
Zone 0: what happened in 2026
AB 3074 directed the Board of Forestry to write "Zone 0" rules for the first 5 feet around homes in fire hazard areas. The Board adopted emergency regulations on August 19, 2026 (PublicCEO), then withdrew the package from Office of Administrative Law review in early September 2026 (reported as September 8 or September 11; Wildfire Los Angeles). Reporting on the package described a focus on clearing combustible material within 5 feet of the home, including under decks, rather than tearing out existing decks. As of October 2026, no statewide Zone 0 rule is in force. Follow updates on the Board of Forestry's Zones 0, 1 and 2 page.
Is your home in a fire hazard zone?
CAL FIRE released new Local Responsibility Area maps in 2025. Reporting on the maps lists Very High areas in Orinda (about 5,241 acres, the most in the county), Moraga, Lafayette, Clayton, Danville and Concord (Local News Matters). Walnut Creek and Pleasant Hill were not on that list. Check your address:
- State Fire Marshal fire hazard severity zone maps (statewide viewer)
- ConFire LRA maps: Walnut Creek, Lafayette, Pleasant Hill, Concord, Clayton
- Moraga-Orinda Fire District ordinances: Orinda and Moraga
- San Ramon Valley Fire maps: Danville, Alamo, Blackhawk, Diablo
City notes: Orinda · Lafayette · Danville. Permit basics: deck permits.
Walnut Creek Deck Builders is not affiliated with any fire district or building department. Rules change; confirm current requirements with the agencies above.