How to Level Uneven Concrete Floors

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Concrete can be an affordable yet elegant flooring choice. If you are painting, sealing, decorating or staining a concrete floor and find that it is not level, then there are a few uneven concrete floor options you can do to correct the issue.


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An uneven concrete floor can be unsightly, as well as unsafe. Installing flooring on an uneven concrete can cause buckling and loose boards after the installation. Filling in gaps, cracks and crevices, as well as leveling uneven concrete, will bring up the aesthetic and shore up the structure of the flooring.

Cleaning a Concrete Floor

Before you can address why the concrete is uneven, you need to scrub the floor thoroughly. Years of dust, dirt, grime, oil and grease need to be removed so much that the porous concrete can take on any sealant you intend to put down, as well as the caulk or cement you use to repair problems.


A gallon of warm water and a tablespoon of dish washing liquid mixed together will pick up most of the dirt layer that lies on top of the concrete. For more difficult stains, a commercial cleaner or degreaser can do the trick.

It may seem like a great choice to use on the durable flooring, but never use acid-based cleaners such as vinegar or lemon juice. These can create unsightly marks or etchings on the surface of the concrete flooring.


Testing the Evenness of a Concrete Subfloor

Most subfloors tend to be a little uneven, particularly those that have settled or are in older homes. However, if you have cracks wider than a nickel and divots or dips deeper than 3/16 of an inch, then you need to level the concrete floor.

To test the evenness of a concrete floor, lay a 10-foot long 2x4 board across the surface. If the board leans or has gaps in certain spots, then you can see where the floor is uneven. Hills and valleys that are more than 3/16 of an inch can cause problems for any flooring you plan to place on top of the concrete flooring.


Leveling a Concrete Subfloor

If you have holes, divots or deep cracks, then you will need to fill these in with a mix of cement. Caulking isn't stable enough to fill cracks and chips that are larger than a quarter or wider than a nickel. These larger issues need more work to create an even concrete floor.


Chip the sides and bottom until they are smooth, straight and level. Use a chisel to chip away at the sides and scrape the bottom. Place a healthy amount of concrete leveling compound into a container and mix it to a thin consistency that you can work with. Pour it into the hole or snaking crack, and smooth it out with a putty knife so that it is level with the rest of the floor.

A self-leveling compound will settle into repairs you make with concrete and make them seamless. It can be poured directly onto an uneven concrete floor, typically to a thickness of ¼ of an inch or more. This allows it to cover minor cracks and divots, as well as compensate for the minor hills that create a height variance.

Let the repair material dry for 48 hours or more before you apply a stain, sealant or paint.