Impact Resistance Rating
The impact resistance rating classifies roofing materials by their ability to withstand hail impact, measured on a scale of Class 1 (lowest) to Class 4 (highest) using the UL 2218 steel ball drop test.
How Roofing Materials Handle Hail
The impact resistance rating classifies roofing materials on a scale from Class 1 to Class 4 based on their ability to withstand simulated hail impact without sustaining damage, as tested under the UL 2218 standard. The test drops steel balls of increasing size onto the roofing material. Class 1 withstands a 1.25-inch ball. Class 4, the highest rating, withstands a 2-inch ball dropped from 20 feet without cracking or splitting. Class 4 products are specifically engineered for hail-prone markets.
Impact resistance ratings affect insurance premiums, coverage availability, and claim outcomes.
The UL 2218 Testing Standard
The UL 2218 test is straightforward: steel balls of specified diameters are dropped from 20 feet onto the roofing material mounted on a test deck. Each sample is struck twice in the same location. If the material shows no cracks, splits, or fractures, it passes at that class level. The ball sizes are: Class 1 = 1.25 inches, Class 2 = 1.5 inches, Class 3 = 1.75 inches, and Class 4 = 2 inches. Each class represents a meaningful increase in impact energy.
Passing the test means the material survived the impact without structural failure. It does not mean the material shows no marks or dents; it means the material's waterproofing function remained intact.
Impact Rating on Insurance Claims
When a Class 4 roof is damaged by hail, the hail event was likely significant because the product is designed to resist standard hail impacts. This actually strengthens the claim because the damage overcame a product specifically engineered for hail resistance. Conversely, when a standard (non-rated) shingle shows hail damage from a moderate storm, the carrier may argue the damage reflects the product's lower performance tier rather than an unusual storm event. Knowing the impact rating of the installed product provides context for the damage assessment.
Frequently asked questions
A Class 4 shingle has passed the UL 2218 test without cracking or breaking when struck twice by a 2-inch steel ball dropped from 20 feet. Class 4 is the highest impact resistance rating and is the standard most insurance companies recognize for premium discounts.
In most hail-prone states, installing Class 4 impact-resistant shingles qualifies the homeowner for insurance premium discounts of 10% to 35%. Some carriers require Class 4 products for coverage in high-risk areas.
No credit card required