How to Concrete an Uneven Basement Floor

Vacuum the concrete floor to remove all grit and debris, then thoroughly wash it with a concrete cleaner or detergent to remove all grease and oils. Allow the floor to dry completely.

Apply a thin coat of primer to the concrete floor with a long-handled paint roller or push broom. Coat the concrete well so that the primer gets down into the pores. Do not let the primer puddle anywhere on the floor and let it dry as recommended by the manufacturer.

Mix a self-leveling compound according to the manufacturer's directions. It should have a soupy consistency without any lumps. For best results, add the water slowly to help avoid lumps.

Pour the self-leveling compound onto the floor slowly, starting at the edge farthest from the room's entrance.

Spread the concrete to a thickness of no less than 1/8 inch at the floor's highest point; it will level out on the lower points as it dries. Add more compound, if needed.

Smoothe the compound with a trowel to get an even finish and let it dry for the time recommended by the manufacturer. It should be ready for light traffic in about four to five hours.