Press the mark: a soft, spongy give under your thumb means hail fractured the shingle mat, while a firm spot or raised rim usually points to blistering. That single test resolves most disputes on the spot. Hail damage is frequently covered by insurance because it happens suddenly and impairs function, while blistering is typically treated as a manufacturing or ventilation issue. Whichever you find, photograph it, note the date of your last hailstorm, and call a roofer if the answer still isn’t obvious.
TL;DR:
- Soft, spongy thumb pressure indicates hail damage, while firm spots suggest blistering, making tactile tests crucial for accurate identification.
- Hail damage produces random dents with fractured mats and impacts on metal, whereas blistering results in uniform bumps with intact mats on hot or poorly ventilated slopes.
- Photographing all damage, measuring impact marks, and correlating shingle dents with soft-metal dings strengthen insurance claims and prevent disputes.
- Blistering is caused by trapped gases and moisture expanding with heat, developing gradually, unlike hail which causes instant impact damage.
- Professional inspections with annotated test squares and detailed photos improve claim success chances and clarify damage origin before filing with insurers.
Table of Contents
- Hail Damage vs Blistering: A Side-by-Side Comparison
- How to Spot the Difference on Your Own Roof
- Why Blisters Form and How Hail Damage Ages
- How Adjusters Evaluate the Damage and What to Do Next
- What Photos to Take for a Claim or Estimate
- Your Pre-Inspection Checklist
- What Roofers Actually See That Homeowners Miss
- Get a Professional Opinion Before You File a Claim
- Sources
- FAQ
Hail Damage vs Blistering: A Side-by-Side Comparison
Hail and blistering can look alike from the ground, but up close they tell very different stories. Hail hits are sudden, structural events. Blisters are slow chemical ones. Here’s how the two compare across the traits that actually matter for a roof inspection.
| Trait | Hail damage | Blistering |
|---|---|---|
| Shape/profile | Random dents or craters, often with a dark bruised center | Raised bump with a firm dome, sometimes with a pinhole |
| Mat condition | Fractured fiberglass mat, confirmed by the press test | Mat intact; surface may be cracked but doesn’t fracture |
| Distribution | Random and directional, following wind angle | Uniform, often clustered on hot or poorly ventilated slopes |
| Collateral evidence | Dents in gutters, vents, and soft-metal flashing | No metal damage; confined to the shingle surface |
| Typical cause | Kinetic impact during a storm | Trapped gas or moisture escaping the asphalt layer |
| Insurance implication | Often covered as sudden storm damage | Usually a maintenance or manufacturing issue |
A few things stand out when you walk a roof with this table in hand.
- A single dented downspout near a cluster of shingle dents is one of the strongest signs you’re looking at hail, not age.
- Blister sites that have popped can expose bare mat and look like an impact crater at a glance, which is exactly why the tactile test matters more than the visual one.
- If marks run in a tidy line down one slope facing the afternoon sun, that pattern alone should make you suspect blistering before you even touch the shingle.
How to Spot the Difference on Your Own Roof
Start on the ground before you ever touch a ladder. Walk the perimeter and check gutters, roof vents, and downspouts for small dents or dings. Soft metals bruise easily under hail, and they won’t show a mark from blistering at all.
- Check soft metal first. Dented gutter caps, bent vent covers, or dinged AC housing units are strong corroborating evidence for hail before you inspect a single shingle.
- Follow safe ladder protocol. Use a stabilizer, never inspect a wet or steep roof alone, and stop and call a professional if the pitch or your comfort level says no.
- Run the press test. Press firmly on the suspicious spot with your thumb or a rounded tool. A soft, spongy give means the mat underneath has fractured, the signature of hail. A firm, unyielding spot means the mat is intact, which points to blistering.
- Read the pattern. Random, scattered marks across multiple slopes suggest hail. Uniform bumps concentrated on one sun-facing or poorly vented slope suggest blistering.
- Look at granule loss shape. Hail typically knocks granules loose in a circular pattern around the impact point. Blister granule loss tends to follow the dome of the bump itself.
Pro Tip: Correlate the size of shingle marks with any dents you found on soft metal. If the diameters roughly match, you’ve got strong, defensible evidence of hail, and that pairing carries real weight with an adjuster.
Photograph everything as you go: wide shots of each slope, close-ups of individual marks with a coin or tape measure for scale, and any metal collateral you find nearby.
Why Blisters Form and How Hail Damage Ages
Blistering starts inside the shingle, not on top of it. Trapped volatile gases or residual moisture in the asphalt layer expand when a roof heats up, and that pressure pushes a bubble up through the surface. It’s a slow process, which is why blisters cluster on sun-facing slopes or areas with weak attic ventilation, and why they often appear in batches tied to a specific manufacturing run rather than a specific date.
Hail works the opposite way. A hailstone strikes with enough kinetic energy to fracture the mat instantly, which is what makes the press test so reliable: the damage happened in one storm, not over months of heat cycling.
Some roofs show both conditions at once. A shingle bundle with a manufacturing flaw might blister for years, then take a real hail hit the following spring. That mix complicates a claim because it forces an adjuster to separate pre-existing wear from storm damage during the same inspection.
- Blisters: gradual, heat driven, tied to material or ventilation.
- Hail: sudden, impact driven, tied to a specific storm date.
- Mixed roofs: require careful, mark-by-mark documentation to avoid over or underclaiming.
How Adjusters Evaluate the Damage and What to Do Next
Insurance adjusters don’t eyeball a whole roof and guess. They mark off 10 foot by 10 foot test squares on each slope, count functional hail hits inside that square, and photograph every one with annotations. Functional damage means the mat is fractured, not just cosmetically marked, so the press test you ran earlier lines up directly with how a professional grades the roof.
Here’s the playbook to follow once you suspect storm damage:
- Photograph every affected slope, plus close-ups of individual marks and any soft-metal dents.
- Pull historical weather reports for your address to confirm the hailstorm date.
- Schedule a professional roof inspection within the first 48 hours if possible, before more weather can obscure the marks.
- Submit your claim with photos, test square counts, and the storm date attached.
If your claim gets denied, you still have options. You can request a reinspection with a different adjuster, hire a public adjuster to advocate on your behalf, or invoke the appraisal clause in your policy if it’s available. Each path works better with the same evidence: annotated photos, test square documentation, and a clear timeline tying the damage to a specific storm.
What Photos to Take for a Claim or Estimate
The right photos do more convincing than any written description. Shoot a wide overview of each slope, then close-ups of individual marks with a coin or ruler in frame for scale. Include soft-metal collateral, gutters, downspouts, and vent covers, since those images often settle disputes faster than shingle photos alone.
- Wide slope overview showing orientation (north, south, east, west facing).
- Close-up of each mark with a scale reference next to it.
- Soft-metal dents on gutters, flashing, or vent caps.
- Annotated test-square photos showing counted hits inside the marked area.
Label every photo with the date, time, and roof location before you upload or print them. A hail crater close-up typically shows a dark, bruised center with a fractured mat visible underneath the granules. A popped blister close-up shows a shallow dome with exposed mat but no surrounding bruise, a distinction worth noting since popped blisters can visually mimic impact damage at first glance.
Your Pre-Inspection Checklist
Bring this list to your own walk-through or hand it to whoever inspects your roof next.
- Before the inspection: Confirm the storm date and time, check neighborhood reports for hail size, and have your photo folder organized by slope.
- During the inspection: Mark test squares, run the press test at several spots per square, check attic ventilation for signs contributing to blistering, and photograph soft-metal dents.
- Document the negatives too. Note any slopes or zones with no damage; that record protects you if a dispute arises later.
- After the inspection: Request annotated photos, a written report describing mat condition at each test point, and a detailed repair estimate with full scope.
A roofer who skips the press test or won’t mark test squares is skipping the two checks that carry the most weight with insurers.
What Roofers Actually See That Homeowners Miss
The most common mistake I see is homeowners calling every raised bump “hail” because it looks dramatic from the ground. Blisters can be just as visible as a hail crater, but they tell a completely different story once you press on them. The second most common mistake is weak documentation. A handful of blurry phone photos rarely convinces an adjuster of anything.
When our crews document a roof, we mark test squares on every slope, photograph each mark with scale references, and note mat condition at every point we press. That level of detail is what separates a smooth claim from a denied one. Homeowners who bring that kind of documentation to their insurer get faster answers and fewer follow-up inspections.
— Mark Griffith
Get a Professional Opinion Before You File a Claim
A professional roofing company can provide Dallas-Fort Worth homeowners with a documented, test-square inspection that holds up with insurers. Instead of hoping your photos are convincing enough, you get annotated evidence, mat-condition notes at every pressed spot, and a written scope your adjuster can’t easily dismiss.
Our inspections cover both diagnosis and next steps. If your roof shows genuine hail damage, we’ll document functional hits inside marked test squares and help you build a claim that reflects the real extent of the damage. If what you’re seeing turns out to be blistering, we’ll tell you honestly, and walk you through repair or replacement options, including financing for a full roof replacement if the shingles have reached the end of their service life. Schedule a roof repair inspection and get a written report with photos before you file anything with your insurer.
Sources
- TWIA property damage evaluation guidance
- Mastering Roof Inspections: Asphalt Composition Shingles, Part 47 — InterNACHI
FAQ
Does Insurance Cover Roof Blistering?
Usually not. Blistering is generally treated as a manufacturing or maintenance issue rather than sudden storm damage, though some manufacturer warranties cover it if it appears early in the shingle’s life.
What Does Blistering on a Roof Look Like?
Blistering shows up as raised, firm bumps that are often uniform in size and clustered on hot or poorly ventilated slopes, unlike the random, scattered dents typical of hail.
Can You Tell the Difference Between Old and New Hail Damage?
Fresh hail hits show bright, exposed mat fibers and sharp edges, while older damage has weathered edges and granule regrowth around the fracture; comparing marks against a known storm date helps confirm timing.
What Does Minor Hail Damage Look Like on a Roof?
Minor hail damage often appears as small, dark bruised spots with slight granule loss, and the press test still reveals a soft give even when the mark looks cosmetic from the ground.
