What a Class A roof is, and who needs one in Butte County
After the Camp Fire, "Class A" went from a line on a shingle wrapper to a question every Ridge homeowner and every insurer asks. Here is what the rating means, where the code requires it, and what it takes to get there on a house that already has a roof.
The rating
Roof coverings are tested by burning a brand on them and by exposing them to flame from below, and rated A, B or C by how long they resist it, with A the best. The rating applies to the assembly: the covering plus whatever is under it, tested together. Fiberglass composition shingles, painted steel panels, and concrete and clay tile all carry Class A listings over a standard deck and underlayment. Wood shake does not, and treated shake only reaches Class B.
Where it is required
California's residential code requires a Class A roof on new construction and on reroofs in any state fire hazard severity zone, in any locally adopted very high zone, and in any area a city or county designates as wildland-urban interface. The state moved those requirements into a new California Wildland-Urban Interface Code with the 2025 cycle, which the Town of Paradise already cites.
In practice: the whole Town of Paradise, where the municipal code requires every new structure and every repair or replacement roof to be Class A. Magalia, Paradise Pines, Stirling City, Forest Ranch, Cohasset, Butte Valley, Yankee Hill, Concow and Berry Creek, which sit in the state responsibility area where most parcels are mapped high or very high. And, since the 2025 state maps, about three thousand acres on the east side of Chico and areas of Oroville that are now very high zones under city jurisdiction. The City of Chico asks for at least Class A, B or a 25-year product on every reroof regardless.
The 50 percent rule
A repair can match the existing roof. But if more than half the roof area is replaced within a year, the whole roof has to become Class A. That rule is in the state code and repeated in Paradise's. It is why a large repair on an old shake or Class C roof usually becomes a replacement, and why a bid for half a roof is worth a second look.
What else the fire code asks of a roof
The covering is only part of it. The wildland code also requires the gaps between the covering and the deck to be fire-stopped (bird stops at tile eaves, for example), ember-resistant vents everywhere air enters the attic, gutter guards, and in Paradise a mesh over skylights. A roof that is Class A with quarter-inch screened vents is still an open door for embers.
Common questions
Almost certainly, if it was installed after the mid 1990s with fiberglass-mat shingles over felt or synthetic underlayment. The wrapper or the manufacturer's website will say "Class A fire rating (UL 790)". The vents are the more likely weak point.
Butte County publishes the 2025 fire hazard severity zone map on its GIS portal, and Chico, Oroville and Paradise each posted theirs. Or give us the address and we will look it up before the bid.
For composition shingle and metal, no; the standard products are already rated. The cost in a fire zone is in the details: listed vents, gutter guards and closed eaves, which add a few hundred to a couple of thousand dollars to a reroof depending on the house.
Have a question about your own roof?
Say what the roof is doing, what kind of roof it is if you know, and which town you are in. We call back to talk it through and set a time to look at it. If water is coming in right now, skip the form and call.