Sealcoating in Ames, IA

Sealcoating is a thin protective coating sprayed or squeegeed over asphalt. Sun oxidizes the asphalt binder and turns a new black driveway gray and brittle within a few years; road salt, gasoline and oil soften it; and water works into the surface and freezes. A sealcoat slows all of that. In Ames, where salt trucks run all winter and spring brings weeks of freeze and thaw, it is the cheapest way to stretch the life of a driveway.

It does not fix structural problems. Sealer will not hold a sunken area up or bridge a wide crack, and painting over alligator cracking just makes a black version of the same failure. Cracks get filled first, and damaged areas get patched before any sealer goes down.

When to seal

• New asphalt: wait until it cures, usually three to six months after paving
• After that: every few years, depending on traffic and how much sun it gets
• Weather: dry, between about 50 and 95 degrees, with no rain expected for a day

In the Ames area that puts most sealing between late May and mid September. A cold, damp October day does not let the sealer cure properly.

How we apply it

We clear grass from the edges, blow and sweep the surface, and treat oil spots so sealer will bond. Cracks are filled. The sealer goes on in one or two coats depending on traffic, and edges along the garage, walk and lawn are cut in by hand. We mark off the area and tell you when you can walk on it and when you can drive on it, typically 12 to 72 hours depending on temperature and humidity.

Sealer types

Most residential work uses an asphalt emulsion sealer. HomeGuide notes that coal tar sealers are banned in many areas, and we do not use them. Lots that carry heavy traffic may get a second coat or added sand for traction.

Sealing parking lots

For businesses, apartments and churches, sealing is usually paired with crack filling and restriping, since the sealer covers the old lines. We seal in sections so the lot stays usable and restripe the same day or the next.

Signs your driveway is due

• The surface has faded from black to gray
• Small stones are loosening and showing on top
• Water soaks in instead of beading on the surface after rain
• Hairline cracks are starting to show
• Oil or gas stains have softened spots where cars park

Any one of these means the protective binder on top is wearing away. Sealing at this stage costs a fraction of what resurfacing will cost once the surface starts to ravel.