How to Repair a Concrete Floor With a Sunken Cracked Corner

If you’ve got a concrete floor in your home, you can’t lay carpeting, flooring or anything else over it unless the surface is firm and flat. Any major failure of the concrete should be repaired by a professional, but if it’s just a matter of a few cracks or a limited area that has sunk, you can level it out yourself with liquid floor leveler, a form of very thin cement. Don’t do this in a basement that regularly takes on water.

Trisodium phosphate (TSP)
Bucket
Mop
4-foot two-by-four (very straight)
Pencil
Floor leveler mix
Power drill with mixing bit

Instructions

- 1
  Add half a cup of TSP to a gallon of hot water in your bucket. Use the solution to thoroughly clean the floor with a mop. Rinse the cleanser off. Let the floor dry for 24 hours.
- 2
  Lay the straight board on its narrow edge, starting in the sunken corner of the room. Assess where the sunken area begins, based on where the floor drops out from under the board. Mark around the sunken area with your pencil.
- 3
  Move the board to the next section of the floor and repeat the process of looking for low spots and marking them. Do the whole floor.
- 4
  Mix a batch of floor leveler in your bucket, using the ratio of water to mix that’s specified on the leveler packaging. Use your drill and mixing bit to combine it. The mixed leveler should be a thin liquid.
- 5
  Pour the leveler slowly over each crack and dip in the floor, starting at the sunken corner. Pour it first into the cracks, then let it spread out over the indented surface. Pour slowly, so the leveler evens itself out. Do all the marked low spots in the room. Let it set 12 hours before adding surface flooring.

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