How to Level a Concrete Floor (Step-By-Step Guide)

When you have a subfloor, slab or foundation that is made of concrete it can settle, shift or be poured incorrectly.

When this happens the concrete floor can become sloped, uneven and out of level.

In this article, we will look at the tools, equipment and methods for leveling a concrete floor.

While most corrections should be done by a trained professional, some options have a DIY potential.

We will also provide a step-by-step model for most small floor projects.

If you find yourself in need of leveling your uneven concrete floor, this is the spot for you. Let’s learn about the process and help you get your flooring back on the straight and narrow.

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Top Reasons to Level a Concrete Floor

There are a lot of reasons concrete can become in a state of disrepair. Not all reasons mean that the concrete slabs become uneven, though. Here are the top reasons for that particular situation.

Deterioration and Time. Concrete doesn’t last forever. Over time and due to conditions it can deteriorate in different areas causing an uneven surface.
Expansion. When slabs are poured there are expansion cracks left to allow for the various expansion and constriction the slabs go through to prevent cracking. Sometimes this can cause them to become uneven.
Bad Initial Pour. When concrete is initially poured, it can settle uneven right from the start. This may go unnoticed depending on where the floor is or how it is used.
Environmental Damage. Weather, natural disasters and other environmental concerns can cause the concrete to buckle, crack or become out of level.

Buyer’s Guide: Tools and Equipment Needed

Before you can level a concrete floor, there are tools, equipment and information you need to consider. Below we cover those factors and tools to help you make a better decision.

Floor Size

The size of the floor you need to level, and in particular the size of the area of the floor you need to level, must be known.

This will tell you almost everything you need to know, including the amount of materials and cost of the project.

The size will also help you understand the time constraints and whether the project should be a DIY or professional install.

Leveling Materials & Tools

The materials needed will also vary depending on the type of project you plan to undertake. As we will outline further below, there are a few different options. The most common (though not the most permanent) is called skimcoating.

This method uses thin liquid concrete that can self level and even out making the overall floor perfectly level. You will need several tools, buckets, mixers, and even lengths of 2x4s for each method, though their particular list of parts will vary.

You may also need expansion foam, caulking guns, scribe tools, hammers, trowels and in some cases a concrete grinder.

DIY or Professional Project

You need to also decide if you plan to tackle the project yourself or hire it out to a professional. With a DIY project you can save a bit of money, but the process is rated as hard to highly difficult.

You need some level of knowledge of the tools and a working knowledge of the materials to complete the job. Hiring the job out also has its level of difficulties. The biggest factor, of course, is the cost.

Cost & Warranty

Finally the overall cost and warranty (if any), need to be addressed. Costs will come in two forms. The first, for DIY projects, will show up as material costs, tool and equipment purchase and rentals and time spent.

The other is for professional installation, where you will pay an hourly labor rate, as well as fees for clean up, man hours and materials. Both options have pros and cons, and only you can decide which is best for your budget and needs.

However, it is important to note that DIY projects will come with no warranty whatsoever. Professional installation, on the other hand, may offer a labor warranty or guarantee that covers the work done and the longevity of the new floor.

How to Level a Concrete Floor – Options

When it comes to leveling your concrete floors, you have a few options. Let’s take the time now to explore the various methods to help you decide which is best for you.

Skimcoating

Skimcoating is a surface solution, meaning you fix the unevenness from the top of the concrete. With this method the subsurface needs to be stable and sturdy, any major damage, crumbling or decay will result in full replacement anyway.

When you skimcoat you use a self-leveling compound, or thinned Portland cement that is designed to spread out and fill in low spots to even the flooring surface.

If you plan to install flooring such as LVP or engineered hardwood over the concrete, this is a great option for leveling your subfloor before the flooring install.

Slab Leveling

Slab leveling is the most expensive option and must be done by a trained and highly qualified professional. However it is the most thorough, long lasting and best option for most situations.

Slab leveling works by fixing the underlying problem with settling or shifting foundations. You bore holes through the concrete slabs to access the underneath, filling the underside with expanding foam or stone slurry. This lifts the slabs back into proper position and removes all traces of slope or unevenness.

This is best used for foundation work, basements and garages where the concrete is usually the base level or foundation of the structure.

Grinding

Grinding uses a concrete grinder with a diamond wheel to remove higher levels of the concrete surface. It is a fast solution and usually inexpensive, but it has lasting ramifications.

For starters, the grinding usually removed a large portion of the concrete surface, exposing the core of the slabs and making the surface rocky. It also doesn’t actually level the concrete but instead removes higher areas to make them the same height as the lower ones.

Over time the root cause of the initial unevenness will continue and the floor will soon be uneven once again.

How to Level a Concrete Floor That Slopes – Step By Step

In this section we will take you through a basic leveling process. Not all projects are the same, though, so this should only be used as a guide to help you understand what a simple leveling will look like.

Our goal is to help you identify the process and tools or equipment needed so you can plan your project with more precision.

Step 1 – Preparation

As with any flooring project you must start by prepping the area. This may be the most tedious part of the process, but being thorough with the first step will mean a better result in the end. Start by removing anything on the floor itself, such as chairs, tables, appliances, etc.

Next you want to remove anything near the floor. Since the level of the concrete will rise you need to remove thresholds, baseboards, trim moldings and other items that are around the edges or may end up “in the way.”

After everything is removed you want to thoroughly sweep the area. This will allow you to uncover any debris that is stuck to the concrete. Use a metal scraper to remove this debris, such as old flooring (laminate, LVP, tile), glue, chipped concrete and other items. The concrete should be smooth and clear after the scraping.

Sweep the area clean once again and then use a wet/dry (Shop) vacuum to thoroughly clean the area.

Step 2 – Damage Repair

The second step is to prepare the concrete itself for the new leveling compound. You want to start by filling in any chipped areas, cracks or gouges. While doing so, you should also inspect the damaged areas to ensure the concrete slab, itself, isn’t corroded or damaged beyond repair.

Using concrete filler and sealant and a caulking gun you can fill in cracks or gaps with ease. You can also use a trowel and smooth the filler into the damaged areas. Once you are done with this step the concrete floor should be clean, smooth and appear whole.

Always allow the filler and sealant to fully dry and cure according to packaging instructions., Some take several minutes and others can take a full day or more.

Step 3 – Find High and Low Spots

The third step is to identify the areas you need to level. This includes both high and low spots and all you need is a floor level and a piece of chalk.

Walk the entire floor area by area using the level as a guide. Find the base level of the concrete and mark areas that are higher with the chalk using a symbol you will easily recognize. Most people use an “X” for high spots.

Also mark areas that are lower than the base level which will need to be filled. Most contractors will use an “O” for the low spots. When you are done your concrete floor will appear like a giant Tic-Tac-Toe board.

Step 4 – Grinding

If you are grinding, now is when you use the concrete grinder. By locating all the high spots you want to use the grinder to wear down the Xs until they are near even with the base level of the concrete.

If you are not grinding, or the high areas aren’t that far off, you can skip this step. However for extreme concrete slopes or pitch, grinding may be your best option.

Step 5 – Leveler Primer

Whether you used the grinder or skipped the previous step, you need to prep the floor for the leveling compound. Using a concrete leveling primer, you want to paint the entire floor space. Be sure to work from the furthest area backward towards the exit so you don’t paint yourself into a corner.

When performing this step you want to take your time. You can use a paint tin and roller, a soft-bristled push broom or a heavy duty paint brush for small areas. You want to apply some pressure when applying the primer to force it into the pores of the concrete.

Note the time when you are finished with the primer. The result should be a smooth, even finish without any puddles or missed areas. Now you need to wait for the primer to dry but not fully cure. This can be anywhere from 4 to 24 hours.

If the primer cures it will not be viscous and won’t have a tacky feel to it. If this happens you will need to apply a second coat, which costs both time and money.

Step 6 – Concrete Leveler

Once the primer is dry to a tacky finish, it is time to start applying the concrete leveling compound. It is important to note two things.

First, you need to start in the area where you began the primer so that it doesn’t dry before you get to it. Working from the far end of the room to the exit is always the best option.

Second, you want to mix the compound and work in smaller areas at a time. With most compounds you will have a small window (about 15 minutes) before it becomes unworkable.

Mix your compound in a 5-gallon bucket according to the instructions. Use an electric drill with a mixing paddle attached to ensure the compound is the right consistency and mixed thoroughly. If you have a second person, one can make a batch of compound while the other spreads the previous batch.

Step 7 – Trowel and Squeegee

Pour the compound over the primer and use a squeegee or trowel to help it get into the corners and along the edges. You want to both push and pull the compound so it spreads evenly.

The self-leveling compounds are designed to move and flow to fill low-lying areas while keeping higher areas even. However, it does dry quickly so a little help with your squeegee will go a long way. If the compound appears to pool or stop spreading, use the trowel to help.

Now, you wait. The leveling compound needs to dry fully before you start using the floor, but most can be walked on in as little as 4 hours. Make sure you follow the directions on the compound you are using, though, as some will make you refrain from stepping on the floor for up to 16 hours.

Most self-leveling compounds on the market today can be walked on in 4 to 16 hours and fully dry in 24.

Step 8 – Clean Up and Inspection

Finally, you need to walk the floor and inspect it thoroughly. Use your level to check for high or low spots and then sweep or vacuum the floor once more.

At this point, if you are happy with the result, you can reinstall baseboards, thresholds and moldings. Once the full cure time has passed you can install flooring over the top (tile, laminate, etc) as needed, replace your furniture in the room and finish the project completely.

Frequently Asked Questions

In this section we will answer some of the more common questions about leveling a concrete floor. If you have other questions or concerns, please use the comment section below.

Q. What is the cheapest way to level a concrete floor?

The cheapest solution is a top-fix using a self-leveling compound. You can find dry mix and premix bags or buckets through Amazon or any home improvement store like Home Depot or Lowe’s. While the preparation and primer can get more expensive, it is still cheaper than renting or buying a concrete grinder or lifting the slabs from underneath.

Q. Can you level concrete by yourself?

In most cases, it should be at least a two person job. Grinder leveling and self-leveling concrete pours take time and effort that are best split between more than one person. A slab lifting solution will require a team and cannot be done by one person.

Q. Can you pour self-leveling concrete over existing concrete?

Yes, self-leveling concrete compounds are designed to fill in gaps, cracks and re-level a concrete floor. However, you will need to ensure the flooring is clean and clear of all dirt, dust and debris. You also need to use a concrete primer for the compound to adhere to.

Q. How many square feet will a 50 lb. bag of self-leveling concrete cover?

When using a 50 pound bag of self-leveling concrete you can expect to cover about 35 to 40 square feet (with a 1/8-inch thick coverage). Thicker coverage will result in less square feet, though, so keep in mind how much you need to pour and how thick it will be to make the floor level.

Conclusion

Leveling your concrete floor that slopes can be a daunting task. It takes a lot of time, patience and materials to get the job done correctly.

If you are planning to use the space for a new flooring (LVP or laminate, for example) the uneven subfloor can be a problem. Self-leveling concrete, grinding and slab leveling are your best options for a smooth even floor.

Hopefully this article has given you insight into the nature of the problem and solutions that meet your needs for your concrete floor.