Sealing an asphalt driveway, also known as "hot top" or "blacktop," is time-consuming but necessary. As water permeates cracks in the material and settles down at the base, the strength of the base is compromised, resulting in the formation of potholes. Cracks filled with water are also an open invitation for damage from freezing in colder climates. Even in warm climates, grass can begin to grow up through cracks on the edges of the surface. Damage from ultraviolet rays and oil or gas spills are other good reasons for sealing asphalt driveways.
Asphalt driveway sealer should be applied within six months of installation, and then again every one to three years thereafter. However, a sealant should not be applied immediately after installation, as the hot top must cure for 30 days. In areas with harsh winters, seal asphalt driveways once per year, but beware of the slick surface that will result.
When planning for sealing asphalt driveways, wait until the ground temperature is 45 degrees Fahrenheit or higher and rain isn't expected for at least three days.
Equipment / Tools
- Stiff-bristled brush
- Push broom
- Garden hose with a spray nozzle
- Application brush
- Pressure washer (optional)
- Asphalt driveway sealer (sealant)
- Patching compounds
- Oil/gas stain detergent
Prep the Area
Remove the grass overhanging the edges of the surface, then sweep the surface clean with a push broom. Use a stiff-bristled brush to clean any oil or gas stains using a detergent specially made for this purpose, which can be found at auto supply stores.
Fill in Cracks and Depressions
Use patching compounds, available at home improvement centers, to fill in large cracks or depressions in the asphalt. Follow label directions for drying time for these compounds.
Spray Down the Asphalt
With the garden hose or a pressure washer, spray down the surface with a vigorous spray to remove dirt missed in the sweeping process. Allow the surface to dry.
Mix the Sealant
With the lid closed, turn the container of the driveway sealer upside down to pre-mix the contents. Once the tub is opened, continue to stir periodically, so that the sealant remains well-mixed.
Apply the Sealant
Beginning in one corner, pour some of the asphalt driveway sealer on the surface. You will probably find it easiest to work on one small square section of about 10 to 20 square feet at a time, rather than doing long narrow strips. Apply your sealant in thin, overlapping coats with a long-handled application brush or squeegee. Keep in mind that putting on a thicker layer of sealant will not provide additional protection, so follow the manufacturer's instructions.
Asphalt driveway sealers are toxic, so avoid skin contact with them by dressing properly and use a mask to avoid inhaling the vapors.
Allow Sealant to Dry
Drying time is a minimum of 24 hours, during which time you should not allow traffic of any kind on the surface. Place barrels at the entrance to your yard to prohibit vehicular access, or simply use the empty sealer tubs. For greater visibility, drive a post into the ground on either side of the entrance, and string some yellow construction tape between the posts.