Effects of Sub-Severe Hail on Asphalt Shingles
A Forensic Engineering Position Paper Clarifying Evidentiary Boundaries Between Material Susceptibility, Normal Aging, and Hail‑Caused Damage
Recent research by the Insurance Institute for Business & Home Safety (IBHS) focused on the cumulative effects of sub-severe hail on asphalt shingles. … The IBHS papers state that small hail in high concentrations damage roofs by reducing their underlying resilience. We have concerns that certain concepts discussed in the IBHS papers could be misinterpreted and/or misused by some and research results presented in the IBHS papers do not adequately support some of their expressed opinions.
Contributions
The IBHS papers contribute meaningfully to the discussion of hail risk by demonstrating that small hailstones dominate hail climatology by frequency. The papers also highlight the role of material aging and weathering on the effects of hailstone impacts, specifically demonstrating that loss of granule surfacing from shingles increases as shingles age (i.e., exposed to natural weathering effects). These efforts can prove valuable in advancing risk modeling and underwriting strategies; however, their efforts are considerably less conclusive when applied to post‑storm damage assessment, which requires a higher evidentiary standard.
Download the position paper for full details.
