How to Seal a Blacktop Crack


Blacktop asphalt driveways provide years of dependable service, but over time, the daily cycle of heating by the sun and cooling at night, as well as common ground settling, can cause cracks to appear in the surface. These small cracks allow water to travel down under the driveway and lead to more serious damage, like potholes. Cracks and separations can be repaired easily, prolonging the life of the asphalt surface and avoiding the expense of retopping or repaving the driveway.

Things You'll Need

  • Screwdriver
  • Stiff-bristled broom
  • Caulking gun
  • Asphalt crack filler
  • Putty knife
  • Asphalt emulsion
  • Asphalt cold-patch
  • Tamper

Small Cracks

  • Clean the loose asphalt, small rocks, weeds and other debris out of the crack with the tip of a screwdriver. Use a broom to sweep the debris away from the crack.

  • Fill the crack to slightly above the surface of the driveway with asphalt crack filler in a caulking gun. This asphalt filler seals small cracks so water can't seep in.

  • Use a putty knife to scrape the excess filler away and to smooth it flush with the driveway surface.

Large Cracks

  • Clean the loose asphalt and other debris out of the crack with the tip of a screwdriver. Be sure to pull any weeds or remove any small rocks. Remove any pieces of chipping asphalt from the edges of the crack. Use a broom to sweep the debris away from the crack.

  • Use a putty knife to spread asphalt emulsion into the crack, coating the sides as completely as possible. Asphalt emulsion is a pliable oil-based tar that helps asphalt patching material adhere to the existing driveway.

  • Pour asphalt cold-patch into the crack to approximately 1/2 inch above the driveway surface. Cold-patch is a loose mixture of the same oil-based asphalt material that was used to build the original driveway.

  • Use a flat tamper to compact the cold-patch material into the crack until it is flush with the surface of the driveway. Sweep away the excess cold-patch that spreads past the edges of the crack. Do not drive over the crack for 24 hours, to allow the patch material to cure.

Tips & Warnings

  • Letting the bag of asphalt cold-patch sit in the sun for a couple hours before using it makes it much easier to handle and improves compaction.
  • A piece of 4 by 4 post makes a good tamper for compacting asphalt cold-patch.
  • Asphalt emulsion and crack filler are extremely sticky when first applied and nearly impossible to remove from clothing and shoes. Exercise caution to protect the repaired area from being walked or driven on for a minimum of 24 hours after application.

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  • Photo Credit asphalt detail image by dpaint from
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