New Asphalt Shingle Hail Impact Performance Test Protocol and Damage Assessment

Abstract

Laboratory test methods for assessing the hail impact performance of roofing materials were introduced in the 1990s. They are based on older science, in which projectiles match a theoretical kinetic energy and damage is assessed using a binary pass/fail rating based on whether a crack can be detected by expert judgment. The existing test methods do not replicate real-world damage modes, and nearly all products have the same rating, making it difficult for consumers to discern which materials could be used to mitigate hail damage. This paper introduces the science behind a new test method for evaluating the hail impact resistance of asphalt shingles, based on hailstone characteristics data collected in the field coupled with updated diameter-to-kinetic energy relationships. The paper summarizes the ice sphere characteristics, ice sphere manufacturing process and equipment, test sample construction and impact locations, and the damage assessment process and technology. When applied, the new method results in a quantitatively-based shingle performance rating that evaluates the presence and severity of five distinct damage modes.