The Best Fire-Resistant Roofing Materials for New England Homes

What is the most fire-resistant roofing material?

The most fire-resistant roofing materials are non-combustible ones, such as natural slate, clay tile and metal, when they are installed as part of an assembly that has been tested and rated. Untreated wood shakes and shingles are the least fire-resistant common roof coverings. The important word is assembly. A fire rating is earned by the roof covering together with what is underneath it, such as underlayment and decking, tested as a system. The same surface material can rate differently depending on the layers below. For the Interlock aluminum roofing system, the accurate statement is Class A Fire Rated Available, as a complete assembly. That assembly uses two layers of GAF VersaShield® over 15/32-inch plywood, per ASTM E108 / UL 790. Ask any contractor exactly which assembly their rating depends on.

How do roofing fire ratings work?

Roofing fire ratings work by testing a roof assembly against fire exposure from outside and grading it Class A, B or C. In the United States, the standard tests are ASTM E108 and UL 790, which are equivalent methods. The tests look at how well the roof resists flame spreading across its surface, how it handles a burning brand dropped on it, and whether fire penetrates to the deck and attic. Class A is the highest of the three classes, intended for severe fire exposure; Class B covers moderate exposure, and Class C light exposure. A rating applies to the tested assembly. If an installer changes the underlayment or deck from what was tested, the rating may not apply. That is why it pays to read the product literature and ask what assembly is being installed on your home.

How do common roofing materials compare for fire?

Common roofing materials compare roughly like this, from most to least fire-resistant, assuming correct installation. Natural slate and clay tile are non-combustible and are typically rated Class A. Metal roofing does not burn, and its rating depends on the tested assembly beneath it; for Interlock aluminum, Class A Fire Rated Available, as a complete assembly. Fiberglass-based asphalt shingles are commonly rated Class A by their manufacturers, though they do contain combustible asphalt. Wood shakes and shingles treated with fire retardant can earn a rating, depending on the treatment and assembly, and that treatment can weaken with weathering over time. Untreated cedar has no fire rating. Many older New England homes still have cedar, or cedar buried under asphalt. That cedar must be removed when an Interlock roof is installed.

What fire risks do New England roofs actually face?

New England roofs mostly face ember and spark exposure from nearby sources rather than large wildfire fronts. Wood stoves and fireplaces are common here, and a chimney fire can send burning material onto the roof. In dense neighborhoods with triple-deckers and closely spaced homes, a fire next door can drop embers on your roof. In rural and wooded parts of Massachusetts, New Hampshire, Maine and Vermont, spring brush fires before green-up, when dead grass and leaves are dry, can spread toward homes. Embers tend to collect where debris builds up: valleys, gutters, and spots where leaves and pine needles sit against the roof. A non-combustible surface helps, but so does keeping those areas clean. Wildfire is a smaller concern here than in the western states, so a roof's fire rating is one part of a broader home safety picture.

Why is aluminum a strong choice for fire resistance?

Aluminum is a strong choice because the metal itself does not burn and does not feed a fire. Burning embers that land on an aluminum roof have no fuel to ignite on the surface. The Interlock system's rating is tied to its assembly, so the accurate claim is Class A Fire Rated Available, as a complete assembly. No roof makes a house immune to fire. Like any metal, aluminum can lose strength and eventually melt in an intense, sustained fire, and a fire that starts inside the house is a different situation from one landing on the roof. Aluminum has other advantages in New England: it does not rust in coastal salt air, and panels weigh roughly 0.4 to 0.7 lb per square foot. The Guardian Lifetime Limited Material Warranty covers material and finish for the original purchaser while they own the home, transferable once; workmanship is excluded.

How can I make my roof more fire-resistant?

You can make your roof more fire-resistant by choosing a rated assembly and keeping the roof and its surroundings free of fuel. Start by asking any contractor which tested assembly their fire rating depends on, and confirm it is what will be installed. Keep gutters, valleys and roof-to-wall corners clear of leaves and pine needles. Trim branches that hang over the roof or touch the chimney. Have chimneys and wood-stove flues inspected and cleaned regularly, and make sure spark arrestors and chimney caps are in good repair. Vents, eaves and gaps can let embers into an attic, so use appropriate screening where it applies. Keep firewood stacked away from the house. Your local fire department and the state fire marshal's office are good sources for current fire safety advice, and your insurer can explain how your roof type affects your policy.

Common questions