Code & Standard
What Is a Class A Fire Rating?
Also called: Class A fire rating, Class A roof, ASTM E108 Class A, UL 790 Class A
Class A is the highest fire-resistance rating for roof coverings under ASTM E108 / UL 790, indicating maximum resistance to flame spread, burning-brand exposure, and fire penetration into the deck. Wildfire-prone jurisdictions increasingly require Class A roof assemblies, and roofs are a home's largest ember-catching surface.
In plain English
In a wildfire, most homes don't ignite from the flame front — they ignite from embers landing on the roof. The Class A test simulates exactly that: large burning brands placed on the covering, flame driven across it, and the assembly must keep fire out of the deck below.
How class a fire resistance works
ASTM E108 / UL 790 grades coverings A, B, or C by severity of survived exposure: spread-of-flame, burning-brand, and intermittent-flame tests. Ratings can be "stand-alone" (the covering itself) or "by assembly" (covering plus specified underlayment/deck) — an important spec-sheet distinction. Noncombustible metal coverings achieve Class A and contribute nothing to fire load; aluminum systems with appropriate assemblies carry the rating while also resisting the ember-entry points (gaps, valleys, edges) through interlocked construction. Jurisdictions in the wildland-urban interface (California Chapter 7A, parts of BC and Alberta) mandate Class A assemblies, and insurers in fire country increasingly price by roof class.
Why it matters for your roof
Roofs are the wildfire vulnerability: ember showers land there first and longest. A Class A noncombustible roof is the single most effective hardening step a homeowner in fire country can take — and is steadily becoming a code and insurability requirement, with premium implications.
Common problems
Confusing stand-alone vs by-assembly ratings; pairing a rated covering with a non-rated assembly; assuming the rating covers wind-blown ember entry at unprotected vents and edges (vent and detail hardening still matter).
Don't confuse it with
Not to be confused with UL 2218 Class 4 — that's the impact (hail) standard; fire classes come from ASTM E108/UL 790.
- Class A vs Class B/C fire ratings
- Fire rating vs impact rating (separate standards)
Regional & climate notes
Most relevant in: Wildfire-prone regions.
Frequently Asked Questions
Is a metal roof automatically Class A?
Metal is noncombustible, but the official rating belongs to the covering or assembly as tested — premium systems document Class A with their specified underlayment. Check the listing, not just the material.
Does a Class A roof help with insurance in fire zones?
Increasingly yes — carriers in wildfire regions factor roof class into eligibility and pricing, and some states' FAIR-plan alternatives require documented hardening that starts with the roof.
What else should be hardened besides the covering?
Ember entry points: vents (ember-resistant designs), gutters kept free of debris, edge and valley details, and nearby vegetation. The Class A covering is the foundation; details finish the job.
Related terms
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