I recently previewed preliminary findings from the Insurance Institute for Business & Home Safety’s (IBHS) 10-Year Asphalt Shingle Study in a post, When Insurers’ Own Science Shows Small Hail Can Wreck Roofs. At that time, the results suggested what many in the field have observed first-hand: repeated exposure to small, “sub-severe” hailstones isn’t harmless. It can accelerate shingle aging and leave roofs far more vulnerable to later storms.
The peer-reviewed study is now officially published in the journal Frontiers in Materials under the title Sub-severe Hail: The Missing Piece in Assessing Asphalt Shingle Risk in North America. 1 Its conclusions are hard to ignore. IBHS researchers subjected shingles to high concentrations of sub-severe hail, stones measuring between 0.7 and 1 inch, combined with natural weathering in outdoor conditions. The results showed that just two years of this exposure caused shingles to perform more like they were a decade old.
The numbers are striking. Shingles exposed to both natural weathering and small hail became roughly ten times more susceptible to damage from subsequent severe hail compared to new products. Granule loss in particular stood out: once the protective mineral surface was stripped away by repeated small hail, the underlying asphalt became brittle and degraded quickly under UV light. When large hail followed, the weakened shingles experienced dramatically higher damage than control samples.
This research provides scientific backing for what many contractors, roofers, and public adjusters have been arguing in the field for years. “Minor” hailstorms, often dismissed by carriers as merely cosmetic, in fact contribute to cumulative roof deterioration. The reality is that most hailstorms bring a mix of sizes, with small hail far more common than the big stones that grab headlines. Ignoring the impact of frequent sub-severe events overlooks the real-world process by which roofs are damaged and wear down.
The authors also acknowledge that this study is just the beginning. They are already expanding their testing to nine additional commonly used asphalt shingle products over the next two years to assess the consistency of the results across the marketplace. That commitment to ongoing testing is critical because it underscores how little attention sub-severe hail has received in durability standards and risk assessments until now.
For those of us working in the hail claims arena, the implications are fairly clear. This data challenges long-standing opinions by insurance company experts that have denied or minimized damage from small hail. If the science says these storms age shingles years ahead of schedule and set the stage for catastrophic failure in later storms, then dismissing that damage at the claims desk is at odds with the evidence.
Now that the study has been published following peer review, the opinions about small hail causing damage should be stronger than ever. My prediction is that the debate over what qualifies as “damage” will only intensify as IBHS continues its work.
From a long-term and societal perspective, this is not good news. Good news would be that our asphalt roofing products do not get damaged and withstand small hail events. It is far better that no damage occur, because we now have to face paying for more expensive roofs and more frequent roof losses. Insurance premiums will go up unless we can find and place roof products that better withstand the peril of hail.
I join with those in the insurance industry demanding more fortified buildings and building products that can withstand the perils to property. A lower frequency of loss and reduced severity of cost when loss occurs through mitigation efforts is something all of us should support. That is easy to say. So, the question is whether we have the common will to do it?
Thought For The Day
Three Little Pigs… the ‘three little pigs demo.’
—Elon Musk’s shorthand for resilience/stress-testing in high-stakes tech reveals
1 Brenna Meisenzahl, Ian Giammanco, and Faraz Hedayati. Sub-severe hail: the missing piece in assessing asphalt shingle risk in North America. Front Mater., Vol. 12 (2025).