Blistering shingles develop small raised bumps on their surface that eventually pop, leaving shallow craters where the granules are gone. Blisters form when gases or moisture trapped inside the asphalt expand under heat. They're common on Texas roofs, they're easy to confuse with hail damage, and the difference matters for both the repair plan and any insurance claim.
Not sure whether you're looking at blisters or hail? Call Cannon Roofing at (940) 627-1045, 24/7, or request an inspection on our contact page.
What blistering shingles look like up close
A blister starts as a raised pimple on the shingle surface, often no bigger than a pencil eraser. Once it ruptures, it leaves a small, round pit with steep sides and bare asphalt at the bottom. The loose granules wash into the gutters.
Blisters tend to show up in clusters across the whole face of a slope and are frequently heaviest on the sides that get the most afternoon sun. They appear gradually, often within the first few summers after installation.
Blisters versus hail bruises
Adjusters and roofers separate the two by pattern and by what else on the property shows damage.
Signs that point to blistering
- Uniformly small, round pits of similar size spread evenly across the slope
- Raised, unpopped bumps sitting next to the craters
- Nothing else on the property dented: gutters, vents, siding and screens are clean
- Damage heaviest on sun-facing slopes regardless of which way the last storm came from
Signs that point to hail
- Random marks of varying size, concentrated on the slopes that faced the storm
- A soft, bruised feel when the spot is pressed, from a fractured mat underneath
- Matching dents in metal vents, flashing, gutters, downspouts or outdoor equipment
- A known hail date in your area
Why the distinction matters for a claim
Storm damage from hail is the kind of loss homeowners policies are generally written to cover. Blistering is typically treated as a product or wear issue rather than storm damage. An inspection that clearly documents which one you have saves time and disputes with your insurer.
What causes blistering shingles
Trapped volatiles or moisture from manufacturing
If gases or moisture get locked inside the asphalt during production, they expand when the shingle heats up on the roof and push the surface up into a bubble. This is why blistering can appear on a fairly new roof and why some batches blister more than others.
Excess attic heat
A poorly ventilated attic keeps the roof deck hot long after sunset. Shingles heated from below as well as above spend more hours at the temperatures that trigger blisters. Blocked soffit vents, too little exhaust and missing baffles are common culprits.
Dark colors and sun exposure
Darker shingles on west- and south-facing slopes run hotter. That doesn't cause blistering by itself, but it adds heat to a shingle that is already prone to it.
The inspection and repair path
A sensible response to blistering starts with facts, not a sales pitch.
- Inspect and document. We photograph the blisters, check whether any have exposed the mat, and look at gutters and metal for signs of hail.
- Check the attic. Ventilation, insulation over the soffits and deck condition tell us whether heat is contributing.
- Record the shingle details. Brand and product line, along with the install date, matter if the manufacturer's warranty might apply.
- Recommend a path. Light, scattered blistering on sound shingles may just need monitoring and a ventilation fix. Blisters that have popped across whole slopes and exposed the mat mean those shingles are losing their protection and replacement should be discussed.
Our roof inspection service covers every one of those steps, and we provide a free inspection and estimate. Cannon Roofing has worked on North Texas roofs since 1994, and every technician carries the Technician Seal of Safety: background checked, drug tested, factory trained and insured. If the inspection finds real storm damage mixed in, we can also help with the claim.
Because popped blisters shed granules, our article on what granules in your gutters mean is useful reading, and if repairs are needed, our roof repair team handles them.
Preventing more blisters
You can't undo a blister, but you can slow new ones by keeping the attic cooler. Start with a quick look from the attic hatch on a sunny afternoon: if the space feels like an oven and the underside of the decking is too hot to touch, the roof is being heated from both sides. Clear insulation away from soffit vents, make sure exhaust and intake are balanced, and consider a lighter shingle color at your next replacement. On a new roof, proper ventilation also keeps you in line with most manufacturers' installation requirements. If you're replacing a blistered roof, ask the roofer to show you how intake and exhaust will be balanced on the new one, not just which shingle is going on top.
Frequently asked questions
Do blistering shingles leak?
Not at first. A blister removes granules, not the whole shingle. Over time, though, the exposed asphalt breaks down in the sun, and heavily blistered slopes wear through faster than the rest of the roof.
Can blistered shingles be repaired individually?
If only a few shingles are affected, they can be replaced. When blisters are spread evenly across a slope, swapping individual shingles isn't practical because the surrounding ones are affected too.
Could my blisters actually be hail damage?
They can look alike from the ground. The quickest clue is whether soft metals on the property are dented. A close inspection of the pits, the mat underneath and the pattern across slopes settles it.
Want a clear answer on those bumps on your roof? Call Cannon Roofing at (940) 627-1045, day or night, and we'll inspect the shingles and attic, document what we find with photos and explain your options. Or reach us through our contact page.