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What You Need to Know About Roof Fire Ratings

Updated: Sep 29, 2021

Today’s roofing materials are designed to withstand the wrath of Mother Nature, including high winds and impact from hailstones and wind-carried debris. If you are looking to tackle a roof replacement project, make sure you choose a material that offers not just excellent durability and longevity, but also exceptional fire resistance. Here’s a quick guide to roof fire ratings:

What You Need to Know About Roof Fire Ratings

Class A Roofing

This rating for roofing materials is the preferred choice for any home, particularly those situated in areas where wildfires are a common occurrence. A roofing product that has Class A fire rating must withstand severe fire exposure effectively. It means that it has been tested to last 2 to 4 hours before ignition, experience maximum flame spread of 6 feet and resist 15 cycles of a gas flame turned on and off. Asphalt shingles with fiberglass matting, slate and clay tiles fall under this category.

Class B Roofing

Roofing products with a Class B rating are effective against moderate fire exposures. It means that they can last an hour before ignition, experience a maximum flame spread of eight feet and resist eight cycles of a gas flame turned on and off. Roofing materials under this category include pressure-treated wood shakes and shingles.

Class C Roofing

The lowest possible fire resistance rating is given to roofing materials that only provide light fire protection. Roofing products with a Class C fire rating are able to experience a maximum flame spread of 13 feet, resist 3 cycles of a gas flame turned on and off and last 20 minutes before igniting. Untreated wood shakes and shingles, plywood and particleboard fall under this category, but roofing contractors don’t recommend these roof coverings for obvious reasons.

Fire Resistance Ratings for Roof Assemblies

Some roofing materials are assembly-rated, which means they can meet better ratings when combined with other components. For instance, wood shakes with fire-retardant coatings applied are rated Class B. However, they can achieve a higher fire rating when combined with underlying materials and components. This creates a roof assembly or system that can withstand severe fire exposure.

For your roof repair, replacement and maintenance needs, turn to A1 Quality Roofing Inc. Give us a call at (951) 877-4406, or fill out our contact form to request a quote.


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