How to Level Uneven Concrete Floors

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Concrete can be an affordable yet elegant flooring choice.
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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.

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 puck 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.

Patching for Big Problems

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. Nail boards around the area or at any entry ways to contain the leveling compound before you begin to pour.

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. Let this dry thoroughly before you apply a stain, sealant or paint.

Self-Leveling Concrete Compound

A self-leveling compound will settle into the repairs. It can be poured directly onto an uneven concrete floor or pumped on to the surface.

Self-leveling is typically applied at 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.

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

The high and low spots on the floor should be filled with concrete leveling compound.

Fill the low spots, or dips, with the concrete leveling compound before addressing the hills. Level these out with a putty knife. Often filling the dips will also help in reducing the bumps.

Once the concrete fill has dried, place the 2x4 back on the floor to ensure you've created a relatively level concrete subfloor.


Kimberley McGee is an award-winning journalist with 20+ years of experience writing for a variety of clients, including The New York Times, Las Vegas Review-Journal Home section and other national publications. As a professional writer she has researched, interviewed sources and written about home improvement, interior design and related business trends. She earned a B.A. in Journalism from the University of Nevada, Las Vegas. Her full bio and clips can be viewed at

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