A Guide to Roof Fire Ratings

As a homeowner, it’s important to be properly informed about fire rating classifications for roofs — which are Class A, Class B, Class C and Unrated. Roofing systems are rated as manufacturers submit samples of their roofing products to certified testing laboratories for certification. These then undergo tests to determine the fire resistance of the materials.

For a better understanding of how these fire ratings differ, this overview from trusted roofing contractors should help:

Class A

Roofs under this classification are the preferred choice for homes, especially those located in wildfire-prone areas. For a roof to be tagged as Class A, it must be effective against severe fire exposure, meaning it should:

• withstand a maximum flame spread of six feet and a burning brand measuring 12 × 12 inches and weighing 2,000 grams
• last two to four hours before ignition
• resist 15 cycles of a gas flame

Class B 

Roofs in this category are effective against moderate fire exposure. According to residential and commercial roofing contractors, a roof is considered Class B if it can:

• withstand a maximum flame spread of eight feet and a burning brand measuring 6 × 6 inches and weighing 500 grams
• last one hour before ignition
• resist eight cycles of a gas flame

Class C 

Roofs under Class C provide light fire protection. They can:

• withstand a maximum flame spread of 13 feet and a burning brand measuring 1.5 × 1.5 inches and weighing 1/4 gram
• last 20 minutes before ignition
• resist three cycles of a gas flame

Unrated 

This is a classification given to roofs that can’t meet even the requirements for Class C roofing. Take note that most building codes don’t approve of unrated roofing materials, so avoid this type of roofing, as it provides little to no fire resistance.

Contact Arrowhead Roofing Today!

If you’re looking for a contractor that can handle the repair and replacement of a commercial roofs, turn to Arrowhead Roofing! For more than 30 years, we’ve provided our customers with exceptional customer service and excellent workmanship. Call us today at (918) 743-9257or fill out our contact form to start a discussion about your roofing project. We look forward to serving you!