Seal Strip Failure
Also called: broken seal, unsealed shingle, adhesive strip failure
Seal Strip Failure is the breaking of the adhesive bond that holds each shingle course down against the one below. Once the seal is broken the shingle is loose to the wind even if it looks perfectly normal, which makes this the most easily missed form of wind damage.
What it means
Asphalt shingles are held down in two ways. They are nailed through the upper portion, and each course is bonded to the one below by a strip of heat-activated adhesive. The adhesive is what stops the exposed lower edge lifting in the wind, and it is what makes a shingle roof function as a sealed surface rather than a stack of loose tabs.
Seal strip failure is the breaking of that bond. The nails are still holding, the shingle is still in place, and it may look completely undisturbed. But it is no longer bonded to the course beneath it, and it is now free to lift.
Why it is the most missed wind damage
Because there is nothing to see.
A missing shingle is obvious from the drive. A creased shingle is obvious from the roof. A shingle whose seal has broken looks exactly like a shingle whose seal has not, until somebody lifts it.
That means the extent of wind damage on a roof is routinely underestimated. A gust strong enough to strip a few shingles and crease others has usually broken seals across a much wider area, including elevations where nothing visible happened at all. The visible damage marks where the wind won outright; the broken seals mark where it nearly did.
How it is checked
By hand, shingle by shingle, across the slopes in question. A sealed shingle resists being lifted and will usually tear before the bond releases. An unsealed one comes up freely with no resistance at all. The difference is unmistakable once felt.
This is genuinely slow work, and it is why a thorough wind inspection takes substantially longer than a hail inspection. It is also why the finding is worth documenting carefully: photographs of a shingle lifted by hand, with the unbonded strip visible, evidence something that no wide shot of a roof ever will.
Why it matters going forward
An unsealed roof is a roof waiting for the next wind event. The bond is what resists uplift, and without it the shingle depends entirely on its nails and on its own weight, neither of which is sufficient in a strong gust.
So a roof left with widespread broken seals is not merely cosmetically unchanged; it is materially less able to survive the next storm. That is the substance of the claim, and it is why seal strip failure is scoped alongside the visible damage rather than treated as incidental to it.
The age question
Seals also fail without any wind at all. The adhesive hardens over time, and an old roof accumulates unsealed shingles as a matter of ordinary deterioration. Foot traffic breaks seals. So does previous repair work where shingles were lifted to access something.
So the same causation question applies here as everywhere else, and the answer usually lies in pattern and corroboration: seals broken across a wind-facing elevation following a documented event, alongside creasing and missing shingles, read differently from scattered unsealed tabs on a twenty-year-old roof.
Common mistakes
Not checking at all is the most common, because it takes time and shows nothing from a distance.
The second is failing to photograph the check, which leaves the finding unevidenced.
The third is assuming reseating solves it. Adhesive that has been broken does not reliably rebond to original strength.
On the call
A homeowner reporting shingles that lift or flap in the wind but are not missing is describing broken seals, and that is worth an inspection even though nothing looks wrong from the ground. Capture which elevations and whether it happens in ordinary wind or only in storms.
This is how our agents handle it on storm appointment calls and day-to-day roofing answering service intake.
Questions people ask about seal strip failure
- How is a broken seal identified on an inspection?
- By lifting the shingle by hand. A properly sealed shingle resists and will tear before it releases; an unsealed one lifts freely with no resistance. It is a physical check rather than a visual one, which is why it is missed by anyone assessing a roof from the ground.
- Do broken seals reseal themselves in hot weather?
- Sometimes partially, because the adhesive is heat-activated and warm conditions can allow some rebonding. It is unreliable, and a seal that has been broken and partly rebonded is generally weaker than an original one, so it should not be assumed as a remedy.
- Is seal strip failure covered as wind damage?
- It can be where it results from a wind event, and it is frequently scoped alongside creased and missing shingles. Seals also fail with age as the adhesive hardens, so the same question of cause arises here as everywhere else on a roof claim.
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