Fire-Rating Shingles


Have you heard of fire rating your shingles? Or is it one of the terms that someone says and you just shake your head because you feel like it’s something you should know, but you don’t actually know. I decided to do some research.

Fire rating your shingles is just putting them into categories of how fire-resistant they are, not fireproof, we have to remember that. Shingles are put through a variety of tests to see how fire resistant they are. After the tests are complete the shingles are ranked given a class. The classes are, Class A, Class B, Class C, and unrated. I will explain those more later.

Testing Shingles
They are tested in a couple different areas. One is flame penetration. If fire starts on your shingles and the shingles let the fire through into your attic and they allowed flame penetration then they will not be ranked well. The second, is flame spread. Did the flame spread through the shingles into the attic, the rest of the roof, the gutters, or the siding? If it did not then the shingles are rated well. Another test is seeing if the shingles will be dislodged if they are burned and if they will cause embers that will catch other things in the area on fire. As always, the less fire the better rating.

Rated Alone or Together
Some shingles are rated into class “by assembly”. Meaning the shingle has whatever class rating because of other components, not just the shingle. So maybe installation or whatever is right underneath the shingles. The other type of rating, is “stand alone”. Meaning that the shingles are whatever rating without any other materials.

Class, Ranking
Now, let’s talk about “class”, the rating system. Unrated, is the worst. An example would be untreated wood shake. Class B would be Wood Shake that has been treated with fire retardant chemicals. Class A is the very best. A flame could not penetrate through into your attic if you have Class A shingles. Some examples are concrete, clay roof tiles, fiberglass asphalt, and metal roofs.

Obviously Class A is the very best thing you can get for your roof and the most recommended.