Driveway Sealcoating in Denver, CO

Driveway sealing lays a fresh film of binder over asphalt whose own surface has oxidized, and it matters more in Denver than in most cities because the surface ages from three directions at once. Ultraviolet light at a mile up runs roughly 16 percent stronger than at sea level, about 137 days a year bring a freeze and a thaw inside 24 hours, and dry air offers little protection from either. Seal coating adds no strength. It replaces the sacrificial top layer before the stones underneath start to loosen, and on a driveway that has gone from black to gray but still feels solid underfoot, that is the least expensive protection available.

Preparation decides whether a coat lasts. Crews blow the surface clean, cut back grass along the edges, scrape and prime oil drips, and fill any crack wider than a hairline, because sealer is a film and not a filler. Manufacturer specifications treat crack repair as its own step that must dry before coating begins. On Denver driveways the usual candidates are the rectangular block cracks produced by aged binder and large daily temperature swings, plus the joint where asphalt meets a concrete apron or garage slab. Open cracks are priced separately under crack filling.

Timing is tighter here than the calendar suggests. The common manufacturer rule is 50 degrees and rising, with nothing below 50 for the 24 hours after application. NOAA's normals for Denver International Airport show lows at or below 50 on about 87 of the 92 spring days and 77 of the 91 fall days, but on only about 13 summer days. In practice that makes driveway sealing a June-to-early-September job in this city, even though the median last spring frost is May 6 and the first fall frost October 6.

Summer brings its own risk. It is the wettest season at the airport, with 5.83 of the year's 14.30 inches falling from June through August, and hail in Colorado is most common in June. Makers call for no rain for 24 hours after application, so crews watch the afternoon storm outlook as closely as the temperature and start early. Dry air helps: afternoon humidity at the station averages 35 percent in July, and a thin coat skins over fast. That speed is also a trap, since a coat that is dry on top can still scuff under a turning tire.

Product choice is open. No Colorado or Denver restriction on coal-tar sealcoat appears on the national ban lists, and USGS notes coal-tar products are more common east of the Continental Divide, where the city sits. USGS also found house dust in apartments next to coal-tar-sealed lots carried 25 times the PAHs of units near other surfaces. Asphalt emulsion and acrylic sealers are the usual alternatives, and a quote should name the product, the dilution and the number of coats. Published price ranges for each approach are on the cost page.