Roof Codes and Classes Explained

What is a Class-A fire-rated shingle? Is a Class-A fire rated shingle good or bad? What wind speed can a Class-H shingle withstand? Is a Class-4 impact resistant shingle the best or the worst? Below, you’ll find roof codes and classes explained. You’ll also find a brief, simple explanation of what each class is and which rating is best. We also list which roofs are Class-A fire-rated, Class-3 and 4 impact rated, as well as note which roofs have the highest wind rating.

Roof Fire Resistance Classes Explained

The UL 790 (ASTM E 108) classification is a standard fire test. It tests how resistant a roof is to simulated fire. This test is conducted from above the roof and not from below, such as from within your home. Roof fire-resistance is rated on a scale from C to A, A being the best and resistant to severe fire exposure. Class-C fire rating is resistant to light fire exposures.

You want a Class-A fire-rated roof, and, thankfully, all asphalt shingles and steel roofs are Class-A fire-resistant.

• UL 790 Class-A effective against severe fire test exposures
• UL 790 Class-B effective against moderate fire test exposures
• UL 790 Class-C effective against light fire test exposures

Class-A Fire-Rated Roofs

All Owens Corning, GAF, Tamko, CertainTeed, IKO, and Malarkey asphalt roofing shingles are Class-A fire rated. In addition, all metal roofing, including metal shingles and standing seam, are Class-A fire rated. Not all clay roofing tiles are Class-A fire rated. If you’re interested in a Class-A fire-rated clay roof, contact us. Most concrete roofing tiles are Class-A fire rated. If you’re interested in a Class-A fire-rated concrete roof, contact us so we can help you find one. We offer quality clay and concrete roofing tiles from Westlake Royal Roofing.

Roof Impact Resistance Classes Explained

Roof impact ratings are technically broken-down into 4 classes from Underwriters Laboratories (UL): 1, 2, 3, and 4, with 4 being the highest and 1 offering the least impact protection. However, we’re not aware of any roof covering that only meets class 1 or 2. To achieve a Class-4 rating, shingles must endure the impact of a 2-inch steel ball dropped from 20 feet without showing any signs of damage. To achieve a Class-3 rating, shingles much endure the impact of a 1 & 3/4″ steel ball dropped from a height of 17′. Class-2, a 1 & 1/2″ steel ball from 15′. Class-1, a 1 & 1/4″ steel ball from 12′.

You want at least a Class-3 impact rated roof in Colorado because hail storms we get, preferrably a Class-4.

Since a Class-4 impact rated roof covering offers the best protection from hail, if you live in an area of Northern Colorado that’s prone to frequent or large hail, this classification of roof is recommended. However, if you live in a part of Colorado that’s gets smaller hail, a roof with a Class-3 impact rating may be sufficient.

It’s worth noting that most Class-4 impact rated roofs also perform better in high-winds and last longer. Often, the price difference between a Class-3 and a Class-4 shingle is minimal and worth the upgrade.

• UL 2218 Class-4
• UL 2218 Class-3

Roof Wind Classes Explained

Shingle roof wind ratings indicate the maximum wind speed a roof covering, such as asphalt shingles, will stay down and resist being damaged or blown off. The scale is from A, the lowest at 60mph to H, the highest at 150mph. Common ratings are A, D, F, and H.

Some roofs can offer two wind resistance ratings. For example, all of GAF’s asphalt shingles are both Class-F and H wind rated. To achieve the higher wind rating, additional materials are installed.

All of Owens Corning’s asphalt roofing shingles offer Class-F 110mph wind rating. However, some are more wind resistant than others, such as their Duration Flex and Storm lines. Tamko’s Heritage shingles are rated up to 110mph, while their Stormfighter Flex are rated up to 160mph.

Metal roofing, such as standing seam and stone-coated metal shingles, are often wind-rated at 140mph or higher. This is largely due to the fasteners used during installation. Metal roofing uses screws during installation. While asphalt shingles use nails. Screws offer much better holding power than nails and better resist pull forces.

• Class-H (up to 150mph)
• Class-G (up to 120mph)
• Class-F (up to 110mph)
• Class-D (up to 90mph)
• Class-A (up to 60mph)

Wind – ASTM D7158, Class H are rated to withstand winds of up to 150 MPH
Wind – ASTM D3161, Class F are rated to withstand winds of up to 110 mph

If you live in a part of Colorado that is prone to high winds, a Class-F or higher wind rated roof is strongly recommended.

The Bottom Line