Sealcoat Peeling or Flaking: Why a Coating Fails Early

Sealer is a bond, not a paint

A sealcoat works by bonding chemically and mechanically to the asphalt surface. Anything that gets between the sealer and the pavement breaks that bond. Dirt, dust, pine needle residue, oil, old failing sealer, and moisture in the surface are the usual culprits.

That is why preparation is the majority of a good sealcoat job. Blowing, sweeping, edging, degreasing oil spots, and letting the surface dry properly all matter more than the coating itself. A first-rate product over a dirty surface fails. A sound product over a clean, dry, sound surface holds.

Time of year matters as much as technique. Material applied late in the day, late in the season, at this elevation may never cure through, and a coating that did not cure will not stay.

Common reasons a coating fails early

Application over a surface that was not clean is number one. Number two is application when conditions were wrong, meaning too cold, too damp, or too late in the day for the material to cure before evening temperatures drop. At our elevation that window closes early in the afternoon by September.

Over-application is a real cause and an underrated one. Sealer applied too thick does not cure through. It stays soft underneath, and the hard skin on top eventually cracks and flakes off. Building coat on coat over the years without letting the pavement wear between applications creates the same problem.

Traffic returning too soon does it as well. Power steering scuffs on uncured sealer leave marks that become release points later. Cure time is not a formality.

When the pavement is the problem

Sometimes the coating did nothing wrong. If the asphalt underneath was already raveling, the sealer bonded to loose material, and the loose material came off taking the sealer with it. Turn a flake over and look at the back. If there is a layer of sand and stone stuck to it, that is what happened.

Moisture pushing up from below will also lift a coating. Pavement over a wet base, or a shaded area that never fully dries out, can release sealer from underneath. That points to drainage work, not coating work.

Check the pattern before you blame anybody. Failure only in shaded areas points to moisture. Failure under parked cars points to oil. Failure everywhere points to preparation or product.

What to do about it

Do not just coat over failing sealer. The new material inherits the old bond, which is the thing that failed. Loose material needs to come off first, and the surface needs to be evaluated honestly before anything else goes down.

Diagnosis on this one really does need eyes on the pavement, because the fix for a prep problem is different from the fix for a raveling problem and different again from a drainage problem. Call (530) 587-4161 and we will look at it and tell you what caused it.

For an association or a commercial owner, photograph it as soon as you notice and note the date. Condition at the time of failure is far easier to establish in June than in October.

Quick answers

More in the pavement guides and the FAQ, or see every pavement problem we get asked about.