UL Solutions
UL 2218
Impact Resistance of Prepared Roof Covering Materials
How well a roof covering resists a hail-sized impact without cracking, fracturing or separating.
What does the test involve?
A steel ball is dropped twice onto the same point of a specimen. The ball diameter and drop height rise with each class, chosen so the kinetic energy matches a hailstone of that size in a thunderstorm. The result is pass/fail — there is no partial rating.
| Class | Ball diameter | Drop height |
|---|---|---|
| Class 1 | 1.25 in (31.8 mm) | 12 ft (3.66 m) |
| Class 2 | 1.50 in (38.1 mm) | 15 ft (4.57 m) |
| Class 3 | 1.75 in (44.5 mm) | 17 ft (5.18 m) |
| Class 4 | 2.00 in (50.8 mm) | 20 ft (6.10 m) |
Common misconceptions
- Class 4 is the highest class, not a mid-tier one. There is no Class 5.
- A Class 4 rating is a laboratory result. It does not mean the roof will survive a given hailstorm, and it does not mean an insurer will treat damage to it as covered.
- Some carriers in some states offer a premium discount for Class 4 in hail regions. It is neither universal nor guaranteed — ask your own carrier before paying for the upgrade.
Sources (3)
- Insurance Institute for Business & Home Safety (IBHS) — Impact Resistance of Prepared Roof Covering Materials (accessed 2026-08-17)
- UL Solutions — UL 2218 — Impact Resistance of Prepared Roof Covering Materials (standard scope) (accessed 2026-08-17)
- Insurance Institute for Business & Home Safety (IBHS) — Impact-resistant roofing research and hail programme (accessed 2026-08-17)