How To Level A Concrete Floor That Slopes: Step-By-Step Guide

When you think about concrete floors, the first associations that come to mind are probably quality, durability, endurance, and strength. While all of these attributes certainly describe the qualities of a concrete floor, there are some potential issues you could experience. 

If not installed properly, concrete floors can have a number of defects, including cracking, uneven surface, and sometimes a sloping concrete slab. If the floor is constantly cracking, this is a more serious issue that requires professional attention.

However, if you want to level a concrete floor that slopes, it shouldn’t be too big of a project. Today we’ll go through the potential causes and solutions for this problem.

Why does your concrete floor slope?

As always, before mentioning any solutions and creating a strategy to solve a problem, it is necessary to dig a bit deeper and find the actual cause of the issue. Not only will this help access the problem adequately, but it is also the main factor in a long-term solution.

While sometimes the issue may be in the concrete floor itself, oftentimes the core issue lies in the structure of the house itself, whether it be the house foundation or the crawlspace. We will take all the factors into consideration and mention the most common causes

It is important to understand that a sloping basement floor, or any other concrete floor for that matter, maybe an isolated problem that could trigger other issues. On the other hand, this issue could only be an indicator of bigger problems in your home.

1. Foundation issues

Usually, when dealing with slopping concrete floors, the issue isn’t in the floor itself, but in the very foundation of the house. But, how can you know if this is the underlying cause? Besides uneven floors, there could be other issues in your home pointing to the foundation.

If you notice that the flooring is sagging towards the center of the house, this is a very strong indicator that something is wrong with the foundation. You may also notice cracks in the floor, and the interior doors may be jammed as a consequence of uneven floors. 

The consequences of a defective house foundation can also be noticed in the crawl space. In this case, you’ll probably notice mold or even rotting in the crawl space, indicating that there is something wrong with the foundation – which is indeed a big issue. 

Why does this happen? The real issue lies in the lack of stability, as the foundation may start shifting or settling. This is especially dangerous with masonry foundations, since problems with soil may cause breakage in the structure of the foundation. 

Issues with concrete floors may also be a consequence of a poorly built crawl space foundation. If the crawl space starts sagging towards the ground, it will retain some moisture which creates a perfect base for pests and mold. 

2. Crawlspace issues

As we’ve mentioned, one of the possible issues with a sloping concrete garage floor, or any concrete floor for that matter, could be a poorly built or defective crawl space. If you’re unable to detect this issue on your own, there could be some other factors pointing to this scenario. 

A problem with crawl space may also be manifested through jammed doors, wall cracks in the interior of your home, as well as noticeable gaps between walls, or doors and the floor beneath. Any of these issues calls for a detailed inspection of your crawl space.

Can a crawl space be repaired? Absolutely, but when it comes to such serious matters, we always recommend at least consulting with a professional, especially if you’re not experienced in this kind of DIY house repair project.

If there’s a structural issue in your crawl space, in most cases it can be solved using crawl space jacks. Crawl space jacks are basically steel posts that can be adjusted so that they support the crawl space foundation adequately and prevent sagging. 

When you prevent sagging, it is easier to level a sloped concrete floor, but you’ll also prevent the moisture from reaching the crawl space and issues such as persistent mold and pests. 

3. Soil issues

Lastly, we want to talk about the importance of soil quality for your house foundation, as well as your floors, crawl space, and pretty much all the other aspects of house quality. If the soil your house is built on has serious issues, it can be hard fixing anything in the long run.

It is necessary to find adequate, effective solutions for problems such as heavy rainfall, leaks, floods, etc. In case you don’t do anything about this large amount of water, it may reach deep into the soil that is supposed to be the base for your concrete.

All this water could compromise the structure and stability of the soil, making it impossible for it to support the weight of the concrete. This is when concrete slabs start sagging and sinking, which leaves you with uneven concrete floors. 

It could also be that the soil wasn’t spread out and laid out adequately for the slob to come on top. If the necessary grade level hasn’t been achieved, the slab will start settling over time causing the concrete to slop or even crack in certain areas. 

Also, if the majority of the soil’s content is clay, if it gets wet, it may retain some of the water, especially during the rainy season, which will cause it to expand. Later, when it dries out, it will shrink in size, and these abrupt changes will certainly affect the concrete slab. 

How to level a sloping concrete floor?

Now that we’ve detected all the possible factors that could cause or contribute to concrete floor sloping, we can get to actual solutions to this problem. Needless to say, bigger core issues such as faulty foundation or crawl space will require much more time and effort.

When it comes to accessing the core issues we’ve talked about, we certainly recommend hiring a professional to inspect the foundation and the crawl space. In this guide, we will focus specifically on the sloping concrete floor and the best ways to level an uneven concrete floor.

1. Find the core issue

As we’ve mentioned, it is necessary to detect the core issue and do something about it. Otherwise, you’ll just be finding a short-term solution and it is quite possible that the problem will reappear sooner than you may expect.

Whether it be the foundation, the crawl space, the soil, or a problem within the concrete slab itself, it is always advised to take care of the bigger issue first before proceeding to fix your uneven concrete floors.

2. Create a strategy

Before going into any house repair project, and especially a big one such as repairing concrete floors, it is necessary to plan ahead and figure out the best strategy. The strategy also includes budget planning, as well as gathering all the necessary tools and materials.

Once again, we encourage seeking professional help if you’re not experienced in concrete repair or any other house repair project for that matter. Also, it is necessary to determine and evaluate the severity of the damage on your floors.

3. Clean the floors

Before starting any work on your floors, make sure to remove all objects from them, including furniture, carpeting, rugs, and appliances. This will allow you to fully inspect the floors and see if there are any additional cracks or sloping.

Also, clearing the area from all furniture and objects will allow you to clean the floors thoroughly using a concrete floor cleaner. It is necessary to use an adequate cleaner since you want to create a nice base for the material you’ll use to level the floors. 

Cleaning also entails vacuuming (using a suitable vacuum such as a shop vacuum), mopping, and using a broom or any other tool of your choice in order to remove all the debris, dust, and particles from the surface.

In case you don’t own a shop vacuum, or any other appliance you may need to complete this step, you can always rent it.

4. Mark the areas you want to fix

Now that you’re working with a clean concrete floor, it is time to inspect it thoroughly and discover the problematic areas. Make sure to mark each and every one of them, so you know exactly what areas need to be fixed.

You can use a level bar to determine the level of your concrete floor and discover the areas that stick out, in case they’re not visible. Position the level bar on the floor and drag it across to discover any high points that would indicate sloping. 

5. Fix the high points using a concrete grinder

Now that you’ve marked all the problematic areas, it is time to start grinding them down and bringing them down to the desired level by using a concrete grinder. Lay the discs of the grinder flat against the area, and grind moving the grinder back and forth.

Continue grinding down the concrete until you’ve reached the desired point. Make sure to vacuum and remove all of the debris before continuing with the next step. Also, ensure you’re wearing all the necessary protective equipment!

6. Add a layer of bonding agent

Most of the bonding agents will require some diluting, so make sure to follow the instructions on the packaging and create the required consistency by diluting it with some water. Keep in mind that there are bonding agents that won’t require this step.

Grab a nap roller and take a generous amount of bonding agent. Roll it across the floor, making sure it is spread evenly. You want to wait for this bonding agent to dry and become sticky before moving on to the next step. 

7. Self-leveling compound application

Prepare the self-leveling compound as the instructions on the product indicate. Ensure that the consistency is dense, yet runny enough so that it is still flexible and easy to work with and get the desired level. 

For this step, it is best to use a squeegee which will allow you to spread the product evenly and get a flawless result. Make sure to work quickly, as the product will dry down if you wait too long. 

Apply some of the solutions and start moving them around using a squeegee. The layer you create should be about ¼ inch thick. Allow the compound to dry for as long as the instructions say, after which you can apply the desired flooring.

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