A lasting impression

Ice ball tests reveal the impact resistance of TPO membranes

According to statistics culled from the National Oceanic and Atmospheric Administration's severe weather database, the number and severity of hailstorms in the U.S. has increased significantly during the past decade. It's generally recognized within the insurance industry that hail-related claims are rising in number and value. As a result, organizations such as the Roofing Industry Committee on Weather Issues Inc., Institute for Business and Home Safety, and FM Global have focused more of their efforts into characterizing, measuring and understanding hail damage.

There also is a significant amount of discussion within the roofing industry regarding how to characterize hail damage and predicting hail resistance. Hail is a natural phenomenon with many variables, such as size, shape, surface roughness and speed, which can reach up to 100 mph. To further the roofing industry's understanding of hail, our company, GAF, Parsippany, N.J., has been conducting research focused on ice ball testing of various roof systems to reveal the effects substrate and attachment methods have on single-ply impact resistance.

Defining failure

Testing for hail resistance is a complex topic. When combined with other meteorological factors such as ambient temperature, wind speed and direction, and rooftop temperatures immediately preceding a storm, it becomes clear predicting hail damage can be quite difficult.