The Institute of Business and Home Safety (IBHS) and the Underwriter’s Laboratory (UL) developed the UL 2218 classification to establish a national standard for roof impact resistance. Shingles have ratings from Class 1 through 4 based on their resistance to a steel ball simulation test. A Class 4 rating is the toughest.
Shingles classified as “impact-resistant” have a Class 4 rating designed to withstand high winds and hail damage. The shingle rating is not visible by merely looking at the shingles, although the impact rating is typically marked on the cellophane on the underside of the shingle. Most insurance companies offer discounts on monthly premiums to homeowners with this upgraded shingle.