How to Level a Sloped Basement Floor

Remove all objects from the floor, including furniture and debris. Sweep it off to remove dust.

Apply concrete cleaner to remove oil, dirt, grease and other substances that could interfere with adhesion. Phosphoric acid works to remove contaminants while roughing up the surface of the concrete so that it will adhere better.

Repair cracks in the floor with a polymer crack filler. Use a putty knife to push the liquid filler into the crack as far as you can, and wipe away the excess. Let dry before applying concrete.

Create a protective dam around the perimeter of the room by applying expansion tape.

Level out any significant bumps in the floor with a concrete grinder, if necessary. A leveling compound can cover these bumps if they are small enough. Sweep away excess dust.

Prepare concrete mix, according to manufacturer instructions, if you need to raise the floor more than a half inch. Pour the mixture to a half inch below the necessary level. Spread evenly with a trowel.

Prepare your leveling compound according to manufacturer instructions. You will probably need to mix water in with the compound to create the appropriate consistency.

Pour the leveling compound following manufacturer's instructions. If you only need to raise the floor by a half inch, leveling compound is all you need. Spread it with a squeegee, broom or trowel. The compound will naturally fill open areas and create a level surface. Let it dry and settle for a few days before walking on the surface or laying new flooring.