Sealcoating in Olympia, WA

Sealcoating is a thin coating spread over asphalt to slow the damage done by sun, water, oil and fuel. Over time the binder in asphalt dries out and the surface turns gray, rough and brittle, which lets water work its way in. A sealcoat replaces that dark, tight top layer. It does not fix potholes, add strength or bridge wide cracks, so those repairs come first. Around Olympia, sealcoating is mostly about keeping water out of the pavement.

The weather window

Sealer needs dry pavement and mild temperatures to cure. HomeGuide recommends sealing when it is dry and between 50 and 95 degrees, and says most sealers need 12 to 72 hours before traffic. In the South Sound that narrows the season to roughly late spring through early fall, with the driest weeks around July. We watch the forecast closely and reschedule rather than seal ahead of rain.

Preparing the surface

Shade, needles and moss are part of the job here. We blow and sweep the surface, scrape off moss and organic buildup, treat oil spots so the sealer will bond, and fill cracks before sealing. Wide or deep cracks get hot rubberized filler. Where tree roots have lifted a section or the pavement has failed, we recommend a patch first, because sealer over broken asphalt only hides the problem for a season.

How often to seal

HomeGuide puts the resealing interval at 2 to 10 years depending on the sealer and the climate. For most homes here, every few years is plenty. Too many coats stack up into a skin that cracks and peels. New asphalt should not be sealed until it has cured, which HomeGuide puts at 3 to 6 months after paving.

Coal tar, asphalt emulsion and what we use

Sealers fall into two broad families: refined coal tar and asphalt emulsion. Under RCW 70A.440.020, coal tar pavement products could not be sold in Washington after January 1, 2012, and could not be applied to a driveway or parking area after July 1, 2013. Asphalt-based and other non-coal-tar sealers are what get used here. They need good weather to cure, which is one more reason we only seal on dry pavement in the warm months.

Signs it is time to seal

• The surface has turned from black to gray
• Small stones are showing and the surface feels rough
• Water darkens the surface and soaks in rather than beading
• Fine hairline cracks are starting to appear

If the pavement is already broken up, sealing is not the right fix yet. Repairs come first.

Parking lots

On commercial lots, sealcoating is usually paired with crack filling and restriping so the lot looks finished and the stall lines are clear. We section the lot so part of it stays open, and we plan restriping for after the sealer cures.