Driveway Sealcoating in Des Moines, IA

Driveway sealcoating is a thin, two-coat layer of sealer that slows the oxidation of asphalt binder and sheds water, and in a city where pavement freezes and thaws about 80 times a year over damp glacial till, keeping water out of the surface is most of the job. New asphalt is black because its binder is intact. Sun and air oxidize that binder until the surface turns gray, fine stones loosen, and rain starts soaking in rather than running off. Seal coating closes that surface again for a few seasons at a time. It is maintenance, not repair: cracks are filled first, soft spots are patched, and the coat goes on only when the weather allows. The crack filling page covers that first step in detail.

Most of the work happens before any sealer is opened. The drive is swept and blown clean, grass is edged back from the borders, and oil or transmission drips near the garage are scrubbed and primed, since SealMaster's preparation steps call for treating gas, oil and grease spots before a coat goes down. Cracks are cleaned out and filled with rubberized sealant; hot-poured material sets in ten minutes or less, so sealing can follow the same day. Anything soft, sunken or broken into small plates is cut out and patched first. On Des Moines Lobe soils those soft spots usually trace back to water in the base, and that is why this step decides whether driveway sealing lasts.

Application is by squeegee, brush or spray, and the standard SealMaster publishes is two coats, with a third reserved for the busiest lanes of commercial lots. The weather rule is 50 degrees and rising for 24 hours, and no rain expected within a day. At the airport station the normal overnight low is 52.2 degrees in May and 55.2 in September, warmer in between, so the dependable window runs from mid-May to mid-September. May and June are also the wettest months of the year, at 4.74 and 4.94 inches of rain, so a careful contractor moves a date rather than racing a storm.

Bids usually name one of three product families: asphalt emulsion, coal-tar emulsion, or acrylic and polymer blends. No Iowa jurisdiction restricts coal tar on the national ban tally, so it is still sold here, unlike in Minnesota, where application has been prohibited since 2014. The US Geological Survey measures coal-tar sealcoat at 35,000 to 200,000 milligrams of PAHs per kilogram, about 1,000 times the level in asphalt-based products. The material price gap is small: HomeGuide lists coal-tar emulsion at $0.06 to $0.15 per square foot and asphalt polymer emulsion at $0.08 to $0.15, so an owner can ask for the asphalt-based product without much change to the total cost.

The cure is the step owners most often cut short. SealMaster calls for 24 hours after the final coat before traffic, and on the hottest afternoons, of which the airport station averages 18.4 a year at 90 degrees or more, soft sealer scuffs easily under a tire turned in place. Winter then takes over. The city brines streets ahead of storms and bars pushing driveway snow into the street, so piles sit on the lawn beside the drive and melt there. A sealed surface sheds that meltwater; a gray, porous one absorbs it. Most drives here are ready for the next coat after two or three winters.