Metal roofing panels do not burn, and metal roof assemblies routinely earn the Class A fire rating, the highest under UL 790 and ASTM E108. That makes metal a strong choice for a fire-rated roof in wildfire country. But a roof is only as fire-resistant as its weakest detail, and embers usually get into a house through vents, gaps and debris rather than through the roof covering itself. Here is how the rating works and how to harden the whole roof.
What a Class A fire rating means
UL 790 and ASTM E108 are the same basic test published by two organizations. A section of roof, built with the covering, underlayment and deck exactly as they would go on a house, is exposed to three kinds of fire: a flame played across the surface to measure how far fire spreads, a flame turned on and off in cycles, and a burning wood crib, called a brand, set on the surface to see whether it burns through. The assembly earns Class A, B or C depending on how it holds up, with Class A being the toughest to pass.
The rating belongs to the assembly
Steel, aluminum, copper and zinc are noncombustible, so you might expect every metal roof to be Class A by default. Most are, but the rating is given to the tested combination of panel, underlayment and deck. Some listings require a specific fire-resistant underlayment or a barrier board under the metal to reach Class A over a wood deck. Others are Class A with ordinary synthetic underlayment. Ask the installer which listing covers your roof and make sure the underlayment in the bid matches it.
Metal over an existing roof
When metal goes over an old shingle roof, the shingles become part of the assembly. Many systems still carry a Class A listing in that configuration, but not all, and wood shakes under a new metal roof are a different matter entirely. If you are in a wildfire zone, confirm the over-the-top assembly is listed before you skip the tear-off. Our guide to metal over shingles covers the other trade-offs.
House fires and wildfires are different problems
In a fire that starts inside the house, the roof covering matters less than the framing, insulation and interior finishes. A metal roof adds no fuel and does not drop burning pieces, which is a plus. Firefighters do note that a metal roof takes longer to cut open for ventilation than a shingle roof, so working smoke alarms and a clear attic access matter as they always do.
A wildfire attacks from outside, and mostly with embers. A storm of embers can land on a house for hours before any flame front arrives, and most homes lost in wildfires ignite from embers that found something to burn: dry leaves in a gutter, a wood deck, a foam closure strip under a panel edge, or an attic full of insulation reached through a vent screen with openings too large to stop them. A metal roof removes the roof surface itself from that list. The job is to remove everything else.
Hardening the whole roof in wildfire country
Vents
Attic and soffit vents are the most common way embers enter a house. Wildfire-area codes typically call for vents covered with fine corrosion-resistant metal mesh, usually one-eighth inch or smaller, or for vents specifically listed as ember and flame resistant. Plastic vents and standard coarse screens do not qualify. Replacing the ridge vent and soffit vents at the same time as the roof is the natural moment to do it.
Gutters and debris
A gutter full of dry leaves is a fuse that leads to the fascia and roof edge. Metal gutters with metal gutter guards keep most debris out, and what does collect should be cleaned every season. Valleys, the space behind chimneys and the uphill side of skylights collect needles and leaves too; a metal roof sheds them better than shingles, but not perfectly.
Eaves, soffits and closures
Open eaves with exposed rafter tails give embers a place to lodge against wood. Enclosed soffits of noncombustible or ignition-resistant material are the usual fix. At the roof itself, the ends of ribbed panels at the eave and ridge should be closed off. Many installers use foam closure strips, which are fine in most regions, but in a wildfire zone ask about metal closures or fully hemmed panel ends so there is nothing under the roof edge that can smolder.
Skylights and penetrations
Skylights should have tempered or multi-layer glass rather than plastic domes, and their flashing should be metal. Plumbing vent boots, satellite mounts and other penetrations should be sealed and flashed in metal where possible. Every gap is a place an ember can rest.
What surrounds the roof
Overhanging branches drop fuel on the roof and can carry flame to it. Keep limbs trimmed back, keep firewood and plastic furniture away from the walls, and think about the fence or deck that touches the house. A Class A roof on a house with a wood fence tied into the siding is only half protected.
Codes and insurance in fire-prone areas
Many western states and counties have adopted wildland-urban interface building codes for designated fire hazard zones. California’s Chapter 7A is the best known, and it requires a Class A roof assembly along with ember-resistant vents, protected eaves and other measures on new construction and major reroofs in those zones. Other states and localities have their own versions. A permit and inspection are usually required, and a reroof is often the trigger that brings a house up to the current standard, so ask your installer what applies to your address.
Insurers in wildfire regions increasingly look at the roof and the vents before they decide whether to write or renew a policy, and some offer credits for documented hardening. What counts and what it is worth varies by company and state. Call your insurer before you sign a roofing contract and keep the Class A listing, vent product sheets and permit record in a file, as we describe in our insurance and resale guide.
Other fire questions homeowners ask
A metal roof does not attract lightning, and because it does not burn it is a safer surface to be struck than wood or shingles. That and other common worries are covered in our metal roof myths guide. Attic ventilation and underlayment choices also affect how a roof behaves in a fire and in daily life; see our underlayment and ventilation guide for the details that go under the metal.
Finding an installer who knows fire zones
Roofers who work in the wildland-urban interface will know the local code, the approved vents and the inspectors. Our directory lists metal roofing companies by state, and you can narrow it by style and metal to find installers who fit your plans.
Frequently asked questions
Are metal roofs fireproof?
The metal itself does not burn, and metal roof assemblies routinely earn the Class A rating, the highest under UL 790 and ASTM E108. But no roof is fireproof. The rating applies to the whole assembly of panel, underlayment and deck, and a house in a wildfire usually ignites through vents, gaps under the roof edge, debris in gutters and valleys, or windows, not through the roof covering. Metal is an excellent start, not the whole answer.
What is a Class A fire rating?
Class A is the top rating under UL 790 and ASTM E108, the standard tests for roof coverings. A roof assembly is exposed to flame spread, intermittent flame and a burning wood brand on its surface, and it earns Class A if fire does not spread far, the deck does not ignite, and no burning material falls through. The rating belongs to the tested combination of covering, underlayment and deck, so ask for the listing that matches your roof.
Does a metal roof protect against wildfire embers?
It helps a great deal. Embers landing on a metal roof have nothing to ignite, unlike wood shakes or dry debris. The danger is where embers go next: into attic vents, under panel edges that lack closures, into gutters full of leaves, or against wood eaves. Pair a metal roof with ember-resistant vents, metal closures at eaves and ridges, metal gutter guards and enclosed eaves, and keep debris off the roof.
Does a metal roof attract lightning and cause fires?
No. Lightning strikes the tallest or best-grounded object nearby regardless of what the roof is made of, so a metal roof does not raise the chance of a strike. If a strike does happen, metal is noncombustible and spreads the energy across its surface instead of concentrating it, which makes a fire less likely than with a wood or shingle roof. Homes in high-risk areas can add a lightning protection system to any roof type.
Will a metal roof lower my fire insurance?
It may help, especially in wildfire regions where some insurers favor or require a Class A roof assembly and other hardening features before they will write or renew a policy. Any credit varies by insurer and state, and the roof is usually one item on a longer list that includes vents, defensible space and siding. Ask your insurer what they look for before you build, and keep the Class A listing and permit records.