Why roofs matter in wildfires
CAL FIRE's Office of the State Fire Marshal (OSFM) says wind-blown embers cause 60 to 90 percent of home ignitions during wildfires (OSFM). Embers land on roofs, collect in gutters and valleys full of leaves, and get drawn into attic vents. A roof that resists embers, with clean gutters and ember-resistant vents, gives a house a much better chance.
What the rules say
- California's wildfire building standards, long known as Chapter 7A of the building code, now sit in the 2025 California Wildland-Urban Interface Code (Title 24, Part 7). Its roofing section requires a Class A roof assembly (OSFM).
- According to OSFM, the standards apply to new buildings with a permit application on or after July 1, 2008, located in State Responsibility Area fire hazard zones (Moderate, High and Very High) or in Local Responsibility Area High and Very High zones.
- CAL FIRE updated its hazard maps, including Local Responsibility Area maps released in 2025. Check your address on the Fire Hazard Severity Zone viewer.
- Repairs and reroofs on existing homes can be treated differently from new buildings, and cities and the County can adopt stricter local rules. Always confirm with your building department or Permit Sonoma.
What "Class A" means
Roof fire ratings come from standard fire tests and run from Class A (best) to Class C. The rating applies to the whole assembly: the covering plus what's under it. Some coverings reach Class A only when installed over a specific underlayment or deck. Ask your roofer for the product's tested Class A assembly and have it installed exactly that way.
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Details that matter as much as the shingles
- Gutters: keep them free of leaves and needles. The WUI code includes provisions for gutters, and many homeowners add guards.
- Vents: attic and eave vents are a path for embers; ember- and flame-resistant vents are available.
- Edges and valleys: debris collects here; keep them clear and make sure metal flashing is intact.
- Skylights and solar: ask how penetrations and panels are flashed and fire-rated.
Local context
CAL FIRE records 36,807 acres burned and 5,636 structures destroyed in the 2017 Tubbs Fire (CAL FIRE), and 67,484 acres and 1,528 structures destroyed in the 2020 Glass Fire (CAL FIRE). The County's after-action report on the 2019 Kincade Fire counts 77,758 acres burned and 374 structures destroyed, with more than 186,000 people evacuated (County of Sonoma).
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Sources
- CAL FIRE OSFM: Building in the wildland
- CAL FIRE OSFM: Fire Hazard Severity Zones
- CAL FIRE: Tubbs Fire
- CAL FIRE: Glass Fire
- County of Sonoma: 2019 Kincade Fire after-action report
- Permit Sonoma
Sources checked October 18, 2026.
Frequently asked questions
Is metal roofing automatically Class A?
Not automatically. The rating depends on the tested assembly, including what's under the panels. Ask for the specific Class A listing.
Do I have to upgrade to Class A when I repair my roof?
It depends on your location, the size of the repair and local rules. Ask your building department or Permit Sonoma before work starts.