How to Repair Cracks in Concrete Floors

By Jeff Beneke

Updated 09/19/19

Worker kneeling and filling in concrete on the floor.

Peter Muller / Getty Images

Tough as it is, concrete tends to develop small cracks and chips. Minor problems like this generally do not indicate any structural problems that require resurfacing, but it is best to tend to cracks as soon as possible. Once a small crack or chip appears, future wear and tear will only cause it to expand. Here's how to fill a crack 1/4- to 1/2-inch wide. For smaller cracks, follow these instructions.

  • Difficulty: Easy
  • Time required: One to two hours

What You Need

  • Wire brush
  • Vacuum cleaner or Shop-Vac
  • Cold chisel
  • Hammer
  • Safety glasses
  • Concrete bonding adhesive
  • Paintbrush
  • Sand mix
  • Trowel

Directions

  1. With a wire brush, clean the crack. Sweep away any loose debris, then vacuum the crack. If grease, oil, or dirt remains in or near the crack, clean it thoroughly.
  2. With a cold chisel and large hammer, undercut the edges of the crack. This will help hold the patch in place. Be sure to wear eye protection.
  3. With a small paintbrush, coat the crack surface with concrete bonding adhesive. Allow the adhesive to dry completely.
  4. Mix a suitable amount of sand mix with water as instructed on the bag. (Sand mix is one variety of dried concrete products sold in bags on home stores.)
  5. With a trowel, fill the crack thoroughly with the mixture. Smooth and level the surface.
  6. Allow the patch to cure undisturbed as instructed on the bag.