Class A fire rating

Class A is the highest of three classes, A, B and C, that ASTM E108 and UL 790 assign to a roof covering tested as installed on a deck, with the underlayment the test used. The methods are titled fire tests of roof coverings; the class attaches to that covering-on-the-tested-deck, never to shingles in a bag. Change the deck or skip the named underlayment and the class does not follow.

Who requires it. California's CWUIC 504.2 requires a Class A fire classification tested to ASTM E108 or UL 790 in mapped fire hazard areas (requirement). The 2024 IWUIC model code specifies a Class A tested roof assembly for Class 1 and 2 construction (requirement). Colorado's 2025 CWRC specifies a Class A covering or assembly (requirement). IBHS Wildfire Prepared Home specifies a Class A roof covering (requirement). Oregon R327, where adopted, is the one people trip on: its floor is a Class B-rated assembly equivalent, with wood shakes and shingles not permitted. Class A is not an Oregon mandate.

Reading a listing. California's OSFM handbook category 8180 lists non-wood roof covering assemblies by ID, each naming the covering, deck and underlayment tested; how to read a Class A roof listing walks one row. Metal roofs are not automatically Class A: two Metal Sales Image II rows on this site name different decks for the same covering family. IBHS also treats a debris-covered Class A roof as failing its checklist; the class is a test result, and the roof still has to be kept clear. The roofing hub holds the listed products and the places where the rule differs.