Your roof does more than cover your home or protect from the weather; it also has a fire prevention purpose. Among the desirable qualities of a good roof, fire resistance is one of them. Especially if you live in an are prone to wildfires or frequent fire outbreaks, you should factor the fire prevention ability of your roofing material. Embers blown by the wind can set fires to homes in wildfire-prone areas. Even if you live in an area not prone to wildfire, you still also need to pay attention to the fire-prevention properties of your roof. Your home, it is said, is only as fire-proof as your neighbors.
Due to these factors, there exist building regulations and codes as well as insurance requirements, for the fire prevention ability of roofing materials, known as fire rating.
What is a roof fire rating?
Fire rating is the measure of resistance to fire, either from above the roof system or from underneath the roof deck, that is, the building interior.
The rating of roofs from above the roof is divided into Class A, B, C or unrated.
Class A is the highest rating, offering the most resistance, and unrated is the worst. Examples of Class A roofing materials are tiles, made of concrete or clay, fiberglass asphalt, and metal roofs. Examples of unrated roofs are untreated wood shingles. Unrated roofing materials may be treated with fire retardant chemicals to raise. It’s a rating to a class B.
Materials are classified according to standardized fire tests. The method of testing is, however, a little different for different materials.
For roof decks that are non-combustible such as steel or concrete, the spread of flame on the top or outer surface is evaluated.
- Class A fire rated roof should have a maximum flame spread of about 6 feet
- Class B fire rated roof should have a maximum flame spread of 8 feet
- Class C fire-rated roof should have a maximum flame spread of 13 feet.
The slope on which the testing is done is selected beforehand, and the maximum slope is usually chosen because they burn the fastest due to material melting and feeding the flame.
If the roof material is combustible such as wood, additional tests must be conducted, which are burn through tests, that is, how fast the fire would burn through the roofing material.
What fire-rating should your roof have?
Of course, when it comes to a fire-prevention-led choice, class, A fire rated roofs are the best choice, but in some cases, you might choose a class B or even C.
You should ensure to check and confirm what the building codes and insurance requirements in your area are. For example, building classified as high-risk, such as theaters, schools and hospitals require a class A rating, while less critical structures might only need to satisfy a class B or C.
Overall, the choice of roofing material, concerning fire rating requires expert advice, and you would do well to contact a licensed and reputable roofing contractor for expert advice.