UL Solutions · ASTM International
UL 790 / ASTM E108
Standard Test Methods for Fire Tests of Roof Coverings
How a roof covering performs against a fire coming from outside the building — a wildfire ember, a neighbour's house, a chimney spark.
What does the test involve?
The two documents use the same test methods. The assembly is evaluated for flame penetration through the covering and deck into the attic, flame spread across the surface, and whether it throws burning brands.
| Class | Fire test exposure | Also required |
|---|---|---|
| Class A | Severe | Does not slip from position; unlikely to produce flying brands |
| Class B | Moderate | Does not slip from position; unlikely to produce flying brands |
| Class C | Light | Does not slip from position; unlikely to produce flying brands |
Common misconceptions
- The class belongs to the assembly, not the shingle. A Class A shingle over the wrong deck or the wrong underlayment is not a Class A roof.
- Untreated wood shakes do not carry a class rating. Reaching one requires pressure-impregnated fire-retardant treatment.
- Class A is the best, not the worst. The lettering runs opposite to school grading intuition for some readers, but A is severe-exposure protection.
Sources (3)
- UL Solutions, Code Authorities — Standard Test Methods for Fire Tests of Roof Coverings (accessed 2026-08-17)
- Intertek — ASTM E108 — Fire Tests of Roof Coverings (test scope) (accessed 2026-08-17)
- ICC Evaluation Service (ICC-ES) — ASTM E108 — fire tests for roof coverings (accessed 2026-08-17)