IBHS tests the impact resistance commercially available asphalt shingles using both 1.5- and 2.0-inch diameter laboratory manufactured hailstones using the IBHS hail impact testing protocol. Laboratory and field research by IBHS has shown that the impact energy and material properties of laboratory hailstone sizes can be directly related to typical natural hailstones in non-wind driven conditions.
While these tests do not exactly replicate natural hailstone impacts, they provide a way to compare relative product performance in controlled, repeatable laboratory tests.
The Relative Impact Resistance of Asphalt Shingles report, describes results from tests on 22 different asphalt shingle products produced by five different manufacturers. The additional reports support and expand on this research.