What Is a Class A Fire Rated Roof, and When Does California Require One?

What do Class A, B and C mean?

ASTM E108 (the same test as UL 790) exposes a roof covering to flames and burning brands from outside the building: an intermittent flame test, a spread-of-flame test, burning and flying brand tests and a rain test. The result is one of three classes:

In every class, the covering must not slip from position and is "not expected to present a flying brand hazard". UL notes that a Class A roof can be used anywhere a Class A, B or C roof is required.

Is it the material or the whole roof that is rated?

The whole roof. UL rates roofing systems as combinations of materials on a stated deck, and the rating depends on the deck, the underlayment and any required layers, not only the visible covering. California's fire code says the same: where an underlayment is part of the rating, it must be "tested as part of the roof assembly" for Class A. The Insurance Institute for Business and Home Safety (IBHS) is blunter about flat roofs: "The membrane alone is not considered Class A, only the tested assembly is."

The code does list a few assemblies that count as Class A without testing: brick, masonry and exposed concrete, and metal, clay or concrete tile and slate, but those only "on noncombustible decks". Most California homes have wood decks, so their tile, metal or shingle roof is Class A because it is installed as a listed, tested assembly. That is why the installation matters as much as the product.

State law also requires the installer to "provide certification of the roof covering classification" to the owner (Health and Safety Code 13132.7). Keep it with your house papers; insurers and buyers ask.

Which roofing materials can be Class A?

When does California require a Class A roof?

The rules moved on January 1, 2026. Wildfire construction rules that used to sit in Chapter 7A of the Building Code and Section R337 of the Residential Code now live in Part 7 of Title 24, the California Wildland-Urban Interface Code. It applies in all State Responsibility Area fire zones, in local High and Very High Fire Hazard Severity Zones, and in areas a city designates.

Some Southern California cities are stricter. The City of Los Angeles bans wood shake and wood shingle roofs anywhere in the city, and the City of Pasadena bans wood roofing in its Very High, High and Moderate zones (see roofing in Pasadena). The City of Santa Barbara requires Class A or noncombustible roof coverings on existing buildings and repairs in its High Fire Hazard Area (see roofing in Santa Barbara).

How do you find your fire hazard zone?

• Enter your address in the Office of the State Fire Marshal's Fire Hazard Severity Zones viewer. The State Responsibility Area maps took effect April 1, 2024.
• Local Responsibility Area maps were reissued in 2025 in four phases. Los Angeles County's were issued March 24, 2025; Ventura and Santa Barbara counties' on March 10, 2025.
• Local agencies then adopt them, and "shall not decrease" the zones the state recommends, though they may add to them. The Ventura County Fire Protection District adopted its maps by ordinance effective July 1, 2025; Fillmore, Oxnard and Ventura adopt their own.
• If a parcel falls in two zones, Ventura County Fire applies "the highest FHSZ" to the whole parcel. Ask your city or county which map and zone apply to your address.

The State Fire Marshal notes the maps show "hazard," not "risk": the physical conditions over a 30 to 50 year period, without counting home hardening or recent fires.

Eaves, valleys, vents and gutters: the rest of a fire-safe roof

A Class A covering can still let fire in at its edges. In the zones where it applies, the 2025 Wildland-Urban Interface Code sets rules for the parts around it:

• Air spaces under the covering. Where a profiled covering such as barrel tile leaves an air space over a wood deck, the code asks for a 72-lb mineral-surfaced cap sheet on the deck, an inch of noncombustible material, or a listed underlayment tested as part of a Class A assembly (504.2.1). IBHS adds noncombustible bird stops at the eave ends of barrel tile and corrugated roofs.
• Valleys. Valley flashing of at least 26-gauge corrosion-resistant metal over a 36-inch-wide, 72-lb cap sheet running the full length of the valley (504.2.2). Valleys collect leaves, which IBHS notes are "particularly susceptible to ignition from embers".
• Gutters. Noncombustible gutters and downspouts, with "an approved means to prevent the accumulation of leaves and debris" (504.4).
• Vents. Attic and roof vents listed by the State Fire Marshal as flame and ember resistant, or tested to ASTM E2886 (504.10). CAL FIRE's home hardening advice is 1/16 to 1/8 inch noncombustible, corrosion-resistant metal mesh over vents.
• Skylights. Operable skylights need a noncombustible mesh screen with openings no larger than 1/8 inch (504.8.2).

Why the roof matters in a wildfire

CAL FIRE puts it directly: "The roof is the most vulnerable part of your home." It adds that embers can ignite homes "up to a mile away", and a roof is a large surface where they land and collect. IBHS, citing a 1981 study of the 1961 Bel Air Fire in Southern California, reports that 50% of homes with wood roofs within 30 feet of burning vegetation ignited, against 24% of homes with fire-resistant roofs.

IBHS's conclusion: "To minimize the threat of direct ignition by embers, a properly maintained Class A roof is required." It also notes that roof valleys collect organic debris, which is "particularly susceptible to ignition from embers", so keeping valleys and gutters clear is part of the maintenance.

Does a Class A roof lower insurance premiums?

Yes, it can. The Department of Insurance's "Safer from Wildfires" program says "Every action under Safer from Wildfires will qualify you for an insurance discount." Under its regulation (10 CCR 2644.9, effective October 14, 2022), insurers' rating plans must take into account building hardening measures, starting with a "Class-A Fire Rated Roof", along with enclosed eaves, fire-resistant vents, upgraded windows and six inches of noncombustible clearance at the base of the walls. The program says "most roofs qualify including asphalt shingles, concrete, brick, or masonry tiles, and metal shingles or sheets", and that wood shakes are not Class A.

The California FAIR Plan's home hardening discounts, effective August 23, 2023, require a Class A roof together with its other listed measures for the structural discount. No source sets a fixed discount amount; ask your insurer or broker what applies to your policy.

What about Zone 0?

Zone 0 is a separate rule about the first five feet around a house, not the roof. The Board of Forestry and Fire Protection's page says its Zone 0 regulations are still in final review with the Office of Administrative Law, so there is no effective date yet.

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