Replacing a driveway can be one of the costliest home improvements out there. That's why many homeowners opt to seal an old, cracked driveway at least one or two times before seriously considering a replacement.
Sealing asphalt with coating has long been a standard project that's more than just a quick patch for cracks and pitted asphalt. It can add years to the life of your driveway, extending its usage before a complete replacement is required.
What Driveway Coating Is
Driveway coating, or repair sealant, is a rubberized tar-like liquid that seals old asphalt and concrete surfaces. Manufacturers claim that it is more durable and less messy than tar, and many formulas contain an aggregate (such as sand) for greater durability.
Driveway coating comes in large buckets and can be applied with a squeegee or broom. Many types offer low- or no-VOC (volatile organic compounds) content, making them much less noxious than traditional tar-based sealers.
Some driveway coatings have a thick consistency, much like gel, for filling in pits and depressions in the asphalt. Other coatings are more liquid-like, and these are ideal for more cost-effective fixes that don't require as much repair work.
Why Seal Your Driveway
Replacing an asphalt driveway is very expensive. Expect to pay a minimum of $8 to $14 per square foot. Removing an existing driveway will drive up the price even more.
So, it makes sense to consider sealing the driveway. Sealing asphalt or concrete helps it last longer and look better while you put off the inevitable replacement.
The main enemy of any driveway is moisture. When cracks appear in a driveway (and they always appear in a driveway), moisture infiltrates into the paving and widens the cracks. The water erodes the base materials below the surface, leading to settling and holes. If it freezes, the water in the cracks expands and promotes more cracking.
Sealing the driveway helps keep moisture out of cracks of all sizes, even those you can't really see. Large cracks are harder to cover and should be filled with a compatible caulk so the sealer can bridge over the top. The sealer also renews the look of a driveway by giving it a consistent color.
Driveway sealant is a deep black color and the texture smooths out the aggregate. It doesn't completely bridge over all imperfections, though. For that, you'll need to either remove and replace the asphalt or you can have the top couple of inches ripped down and topped with new asphalt. Another lower cost alternative to replacement is the tar-and-chip method.
Tips For Applying Driveway Coating
- Start the project early in the warm season by patching large potholes with cold asphalt patch. Cold asphalt comes in 40- and 50-pound bags and, as the name says, doesn't require heating as does traditional hot melt asphalt.
- Start the cold asphalt patch at 2 inches, then compact it down halfway to 1-inch. Continue layering the patch in this manner until you reach driveway level. Then, slightly crown the top of the asphalt patch and pound it firmly so that the edges merge with the driveway.
- Most cold patch asphalt manufacturers recommend a minimum 30 days of curing time before applying driveway coating. Keep the patch exposed to promote curing.
- Like any surface coating, driveway sealer sticks best if the underlying surface is clean and dry. Preparing an asphalt driveway requires a thorough cleaning with a hose or pressure washer. Oily spots should be cleaned with a suitable degreasing cleaner, then rinsed thoroughly.
- Let the moisture fully dry for a day or two. The morning of the coating, blow off any accumulated debris with a leaf blower.
- Concrete surfaces should be washed with a muriatic acid solution, rinsed, then neutralized with sodium hydroxide, and rinsed again.
- Let the driveway dry completely before sealing. Fill large cracks with a driveway caulk product that is compatible with the coating. It's easiest to apply the coating with a squeegee fitted with a long handle. You can also use a large paintbrush for detail work and edges.
- Staying clean while applying driveway coating is difficult, so be prepared to get dirty. Wear old clothing and shoes that you don't mind tossing after the project. Or, wear disposable painter's overalls and rubber boots.