There are four fire ratings for roofs: Class A, Class B, Class C and unrated. A Class A roof offers the best fire protection from above the roofing system. Depending on where you live, it may be required by your building codes. A standard fire test is used to determine the fire rating of your metal or asphalt shingle roof. Learn more about roof fire ratings in this blog post.
It’s the preferred option for all homes and especially for areas that experience wildfires. The roof must endure extreme fire exposure to gain a Class A rating.
Class A roofs experience a maximum flame spread of six feet. They withstand a burning brand measuring 12” x 12” and weighing 2,000 lbs. These roofs can usually last up to four hours before ignition. They also resist 15 cycles of a gas flame turned on and off. The most common materials that have a Class A rating include slate, asphalt fiberglass composition shingles and concrete tile roofing.
Assembly-rated Class A roof coverings are products that meet Class A requirements when combined with specific materials. It’s important to carefully follow the manufacturer’s recommendation if you’re using an assembly-rated roofing material.
Class B roofs resist moderate fire exposures. They take on a maximum flame spread of eight feet. These roofs stand up to burning brand measuring 6” by 6” and weighing 500 grams. It can take up to an hour before they ignite and they can withstand eight cycles of gas flame turned on and off. Pressure-treated shakes and shingles are the most common Class B-rated roofing materials.
Class C roofs only offer minimal fire protection. They experience a maximum flame spread of 13 feet and last 20 minutes before ignition. They resist three cycles of gas flame turned on and off. Untreated wood shakes, shingles, plywood and particleboard are examples of common Class C building materials.
Unrated roofing materials are products that didn’t even meet the minimum requirements for the Class C rating. You should avoid these materials at all costs as they offer little to no fire protection. Most building codes will not permit unrated roofing materials.
For quality roofing products and services, choose Dynamic Roofing Concepts Inc. Whether you need a new tile or metal roof, our experienced team is here to help. Call us at (813) 657-7663 or fill out our online form to get a free quote. We serve clients in Tampa, FL.