What are the classes of impact resistant shingles?
How the UL 2218 test works
Shingles are installed on a test deck, and steel balls are dropped onto them, hitting the same spot twice. Inspectors then look for cracks, splits or ruptures. The shingle earns the highest class it passes:
- Class 1: 1 1/4 inch ball from 12 feet.
- Class 2: 1 1/2 inch ball from 15 feet.
- Class 3: 1 3/4 inch ball from 17 feet.
- Class 4: 2 inch ball from 20 feet.
Other impact tests
- FM 4473 fires ice balls at roofing, mainly rigid products like tile and metal, and uses a similar Class 1 to 4 scale.
- IBHS runs its own testing with realistic hailstones and publishes ratings for shingle products, which some homeowners use alongside the UL class.
Do not mix up the classes
Shingle labels carry several ratings that use the word class. Class A is a fire rating. Wind ratings appear as ASTM D3161 Class F or ASTM D7158 Class H. Only the UL 2218 or FM 4473 class describes impact resistance.
Which class matters for insurance
Carriers that give credits for impact resistant roofs typically require Class 4, and they may ask for proof such as an invoice or certificate. Lower classes rarely change premiums, even though they do perform better than unrated shingles.
What impact resistant really means
A rated shingle resists cracking from hail of a given size. It does not stop granule loss, and it is not a promise of no damage. Manufacturers exclude hail from their limited warranties.
See impact resistant shingles in Georgia and Georgia hail season.