How Do You Level An Uneven Exterior Concrete Slab Properly?

Whether you’re planning to create an outdoor patio, lay the foundation for a shed, or simply want to ensure a safe and even surface, leveling a concrete slab is an essential step in any outdoor construction project.

Uneven concrete can lead to a host of problems, from poor drainage to tripping hazards.

Although concrete is one of the toughest and most widely used construction materials, it is not always without its challenges. Concrete patios, in particular, can become uneven over time.

In addition to being unsightly, uneven concrete patios can also be dangerous, causing a trip-and-fall hazard or even cave-ins that can cause significant injuries. But fear not, as we’ve got you covered!

In order to level an uneven concrete slab, professionals use poly jacking. Using this fast, non-toxic, and simple method, you can level uneven concrete slabs in no time.

In this comprehensive guide, we’ll walk you through the step-by-step process of leveling a concrete slab outside, empowering you to transform an uneven surface into a solid foundation that will stand the test of time.

What Causes An Uneven Concrete Patio?

Uneven concrete patios can be caused by several factors, including:

  • Extreme weather conditions cause natural wear and tear
  • Concrete shifting beneath the soil
  • During installation, incorrect pouring technique was used

Nothing is more frustrating than pouring concrete for a patio only to have it settle unevenly. Your concrete patio should be constructed by a professional to prevent this from happening.

Professional concrete contractors possess the skills and techniques that are necessary for a perfect patio. Outdoor concrete surfaces tend to shift over time due to erosion and other environmental factors.

If the soil is not stamped properly prior to patio installation, it may occur sooner rather than later.

The first thing you should do if you notice soil shift or erosion is to address it immediately since it can lead to much bigger and more dangerous problems under your concrete patio.

All outdoor areas of your home and property will eventually wear out as a result of varying weather conditions over time. Depending on the climate in your area, concrete patios may need to be releveled.

Exterior Concrete Slab Leveling: A Step-by-Step Guide

How To Level Concrete Slab Outside

Even if your concrete patio is uneven for some reason, it’s best to get it fixed sooner rather than later.

If you are concerned about the quality of your concrete, you might want to consider hiring a professional concrete raising company. There are alternative methods available, however, for those who are determined to do the project themselves.

Use a Concrete Leveling Compound

The use of a concrete leveling compound is often sufficient to relevel a concrete patio that is only slightly uneven. A thorough cleaning of the concrete is the first step in this process.

Concrete can be cleaned in a variety of ways, including with a pressure washer or with a commercial acid-based cleaner. For the bonding agent to adhere, a rough surface has to be created by grinding away the top layer of concrete.

Using 2 x 4 or 2 x 6 wooden planks, construct a wall around the slab’s downward-sloping area.

In this way, leveling compound will not flow outside the desired patio area. It may be necessary to fully enclose concrete patios that are in dire need of leveling.

As soon as the slab is free of dust and debris, you can apply the bonding agent. The concrete leveling compound should then be mixed and applied, starting at the sloped end.

When it comes to making the concrete surface flush, a metal trowel comes in handy. After that, it’s time to remove the wooden boards to reveal the now perfectly level concrete patio after the new concrete has dried (typically overnight).

This step-by-step guide provides a more detailed explanation of how to level concrete outside.

Step 1

Remove any dirt from the concrete slab by sweeping it with a broom. If you are going to repair concrete, you will need a clean area to work on. 

The slab can be further cleaned with a garden hose and water or a pressure washer. In order to remove hardened dirt from concrete, a pressure washer can apply much more force. Dry the concrete for about 30 minutes.

Step 2

Fill a new or clean paint tray with about 1/2 gallon of latex primer. Clean brush rollers should be soaked in latex primer. The concrete slab should be coated with primer. About 12 hours should be enough time for the latex to dry.

Step 3

The slab needs to be repaired at the lower, uneven spots. It is best to target these spots specifically to save you the trouble of repairing the entire slab if it is not necessary.

A 2-inch by 4-inch board should be placed on the concrete and the spots where it does not lie flat should be repaired.

Step 4

Fill a bucket with a leveling compound. Use a mixing stick to mix the contents of the bucket according to the manufacturer’s instructions. Mix the water and compound together until no lumps remain.

Step 5

Coat the concrete slab with the compound, smoothing out the coating with a trowel. After mixing the leveling compound with water, it will dry in less than an hour. 

Apply the compound mixture to the slab as needed. Before using the slab, allow it to completely dry for at least 24 hours.

Patching Problem Areas

Patching Problem Areas

There may be a small area of a concrete patio that needs to be leveled if the entire slab needs to be leveled. If this is the case, removing just the affected area may be easier and more practical.

It’s useful to have a jackhammer or concrete cutter on hand, but DIYers should be cautious: these tools can be dangerous. The ground beneath the slab is raised to the proper height by adding material, usually sand.

To prevent future sinking, the sand must be compressed with a tamping machine. The old, uneven concrete piece is then replaced with a new piece cut to size.

Let the slab dry overnight before filling in the cracks with additional concrete (or a concrete compound).

Can You Put Self-Leveling Concrete Over Existing Concrete?

Can You Put Self-Leveling Concrete Over Existing Concrete

Your existing uneven concrete can be overlaid with self-leveling concrete. In reality, this is not a solution to the problem; it is only a temporary one that could worsen the situation rather than solve it. 

Sinking concrete sinks more as more weight is added to it. Concrete that self-levels flows more easily and sets up more quickly than regular concrete. In order to create an even surface on uneven concrete, these products are spread over it.

Self-leveling concrete has the drawback of not being able to level sidewalks, driveways, or patios outside. 

Self-leveling concrete is also not suitable for slabs that have sunk more than an inch. A concrete slab with an uneven surface will require more mix.

Is It Cheaper To Level Or Replace Concrete?

Leveling concrete is cheaper than replacing the entire slab. Concrete leveling and poly jacking solve the underlying cause of uneven slabs, preventing future replacements.

You will have to replace, mud jack, and overlay the surface again in the near future if you use these temporary solutions. Experts estimate that homeowners can save 50% to 80% on concrete replacement by leveling uneven concrete.

Is There Self-Leveling Concrete For Outside?

Yes, self-leveling concrete can be used outside. It is a material that flows and levels itself, making it easier to pour and finish. Self-leveling concrete can also be used to fill uneven surfaces, making it ideal for outside projects.

A self-leveling concrete product is created by combining Portland and/or calcium aluminate cement with organic aggregates, co-polymers, and chemical modifiers, which form a flowable, self-leveling compound.

Call a Professional Concrete Raising Company

A professional concrete mud jacking company should be contacted if you lack experience leveling concrete or have reservations about doing it yourself.

A polyurethane foam or a process called mud jacking can be used to level your concrete slab. Mud jacking involves pumping a slurry mixture under the slab to raise it.

Some contractors prefer polyurethane foam because it is considered a more modern solution, but it does not always completely fill the space under a slab. Chemicals can also be present in polyfoam.

Final Words

A concrete slab that is uneven on the exterior should be repaired both for convenience and safety reasons. If you want to build anything on your slab or lay down any type of outdoor tile, you must have an even concrete slab.

To level out the floor, you can purchase concrete leveling compounds from home improvement retailers. By adding the compound over the existing concrete, you can repair low points that may be problematic.

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