Hail Damage vs. Blistering Shingles
Quick Answer
The adjuster claimed your roof is just suffering from "heat blisters" and denied the claim. Here is exactly how expert contractors prove it is legitimate hail damage.
One of the most common—and infuriating—tactics used by inexperienced or aggressive insurance adjusters is to misidentify authentic hail damage as "Blistering."
Why do they do this? Because hail is a covered weather event, but blistering is a manufacturing defect or ventilation issue, which is explicitly excluded from your policy. If they can convince you the damage is just heat blisters, they legally owe you nothing.
What Are Heat Blisters?
To combat a denial, you must understand exactly what the adjuster is claiming.
Blistering occurs when your attic lacks proper ventilation. In the blistering heat of an Iowa August, the attic acts like an oven, cooking the asphalt shingles from the bottom up. Trapped moisture inside the shingle expands and creates "pimples" or "bubbles" on the surface. When these bubbles pop, they expose the black asphalt underneath, creating circular pockmarks that look shockingly similar to hail hits.
Because blistering is caused by terrible attic airflow (a homeowner maintenance issue), the insurance company is not liable for it.
How to Prove It's Hail (The Irrefutable Evidence)
1. The Fracture Test
When hail smashes into a shingle, it exerts immense downward crushing force. This force crushes the granules deeply into the asphalt and fractures the fiberglass matting at the bottom of the shingle. A popped heat blister pushes upward and outward; it never fractures the bottom matting. If you feel a bruised dent with fractured webbing beneath it, it is hail.
2. Collateral Damage
Heat blisters only affect shingles. Hail affects everything. If the adjuster claims your roof is blistered from heat, but your soft aluminum gutters are dented, and your window screens have circular tears in them, their argument collapses immediately. Heat does not dent metal.
3. The Splatter Pattern
Hailstrikes are random and chaotic. Blistering is uniform. Furthermore, hail hits often rub the oxidation off the metal roof vents, leaving bright, shiny "splatter marks." Blisters leave no such forensic evidence on metal components.
How to Overturn the Denial
If you receive a denial letter claiming "Prior Blistering," do not accept it. The immediate response is to hire an elite local contractor who understands how to dispute technical engineering reports.
Your contractor will demand a re-inspection with a senior adjuster, bringing detailed macro-photography proving mat fractures and accompanying collateral damage reports to physically force the carrier to acknowledge the kinetic impact of the hail.