When to seal an asphalt driveway, and when not to
Sealcoating is the most oversold service in paving. Done at the right interval it genuinely extends the life of a driveway. Done every year, it does harm.
What sealcoating actually does
Sealcoat is a surface coating. It is not structural and it adds no strength. What it does is protect the asphalt binder from ultraviolet light, oxidation, and from fuel and oil that soften it.
A driveway that is never sealed dries out. The binder holding the aggregate together breaks down, the surface goes grey and rough, aggregate starts to come loose, and water gets in more easily. Sealing slows that down.
That is the entire benefit. It is a real benefit, and it is not more than that.
Why annual sealcoating is a mistake
Sealcoat does not absorb into asphalt. It sits on top of it. Each coat adds another layer, and those layers do not bond to each other well.
Apply it every year and the build-up eventually starts cracking on its own, in a fine web across the surface, independent of anything happening in the asphalt below. It looks like driveway failure. It is sealer failure. Stripping it back off is more work than the sealing ever was.
If a contractor offers to seal a driveway every spring, that is a subscription, not maintenance.
The right timing
The first seal coat on a new driveway goes on 60 to 90 days after paving, once the surface has cured and released its oils. Sealing before that traps them and leaves a soft surface that scuffs and tracks.
After that, every 2 to 3 years is the right interval for a residential driveway on Long Island, adjusted for how much sun and traffic it takes. A driveway in full sun with heavy use dries out faster than a shaded one with two cars on it.
The condition of the surface tells you more than the calendar does. A driveway that still looks black and tight does not need sealing. One that has gone grey and feels rough, where the aggregate is starting to show, is ready.
When not to seal at all
Do not seal over structural cracking. Sealer is not a filler and it will not bridge a moving crack. Crack filling is a separate operation and has to happen first.
Do not seal a driveway that is already failing at the base. It hides the problem for one season and changes nothing underneath.
Do not seal in the wrong conditions. Sealer needs dry weather and warm temperatures to cure properly. Applied too cold, too late in the season, or with rain coming, it will not set correctly and will track and peel.
What good sealing looks like
The surface is cleaned properly first, including oil spots, which sealer will not stick to otherwise. Cracks are filled as a separate step before anything is coated. The material is applied at the correct rate rather than thinned out to cover more ground. And the driveway is kept off for the full cure time.
Most of the difference between a sealing job that lasts and one that does not is in the preparation, not the product.
FAQ
How often should a driveway be sealed?
First seal coat 60 to 90 days after installation, then every 2 to 3 years after that on Long Island. Judge the interval on the condition of the surface as well as the calendar. A driveway that still looks black and tight is not ready. One that has gone grey and rough, with aggregate starting to show, is.
Can I seal a brand new driveway?
Not for the first 60 to 90 days. New asphalt needs that time to cure and release its oils. Sealing too early traps them and leaves a soft surface that scuffs and marks easily.
Does sealcoating fix cracks?
No. Sealer is a coating, not a filler, and it will not bridge a crack that is moving. Crack filling is a separate step and needs to be done before sealing.
Is annual sealcoating better than every few years?
No, it is worse. Sealer sits on the surface rather than absorbing, so annual coats build up layers that do not bond well to each other and eventually crack on their own. It looks like the driveway failing when it is the sealer failing.