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sinking slab

Sinking Concrete Slab

Does your driveway, pool deck, or walkway look uneven? If you take a closer look, you’ll notice that unevenness isn’t the only problem.

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If you ever look at the concrete around your property and notice that some of it is uneven, then it is highly likely that it has begun settling. Concrete settling is a term that’s used to describe the way concrete slabs sink when there is a gap in the soil beneath them. When the soil under a slab becomes displaced, it can no longer hold up the slab evenly, causing it to settle. 

The reason these gaps form is due to some sort of soil erosion or displacement. Soil is not a material that stays dormant as it is susceptible to all the events of nature. The soil particles can get moved around by anything, even something as unassuming as the wind. This is especially true for the soil in Grand Junction, which is very sandy and loose. 

sinking slab

What Causes Sinking Concrete Slabs? 

It’s easy to understand how soil can become displaced or how the topsoil of a yard can begin to erode. However, it might be a bit harder to understand how the soil under a heavy concrete slab can become displaced. You may think that the slab will keep the soil from moving about and protect it from water damage, but this isn’t the case. Here are the different ways in which the soil in your yard can become displaced: 

  •  Moisture 

Concrete is an absorbent material. If it’s exposed to sufficient moisture, it will seep through to the concrete and reach the soil. Regular concrete slabs used for driveways, garages, patios, and pool decks are only four inches thick. They don’t do much to stop moisture from getting to the soil, so it’s no surprise that there can be erosion in soil despite the slab on top.  

  • The Freeze-Thaw Effect 

During the winter, the snow around your yard goes through a cycle of freezing and thawing as the temperature changes throughout the day. When the moisture that is in the soil freezes, it expands considerably. As it expands, it moves the soil around. When it melts, the ice may no longer be there, but the gaps it left behind during expansion remain. 

These little pockets of air seem insignificant, but the effects they have on the soil accumulate over time. With every year the soil is allowed to experience the freeze-thaw effect, the concrete has a less stable foundation.  

  • Small Earth Tremors 

Strong earthquakes are not common in Grand Junction. Still, the ground is trembling all the time, and even if we don’t feel it and the impact isn’t immediately there, the small earth tremors do cause the soil to shift around slightly. Grand Junction is also near some of the larger earthquake zones in the western part of the country. The powerful earthquakes that overwhelmingly shake the earth there can ripple through Colorado’s western region, even if we only feel it on a smaller scale. 

  •  Tree and Plant Roots 

As beautiful as they are, trees and plants can cause concrete settling. As the roots grow and extend out in search of moisture, they displace the soil. Even if the tree or plants are removed, the effects of the displacement remain long after they are gone. 

  • Heavy Weights 

Heavy loads can cause soil displacement, even when the soil is under the slab. Displacement by compression is most common in patios, which are usually decorated with large furniture. 

How to Tell If Your Concrete Slab Is Settling 

Knowing what signs to look for when dealing with slab settling is beneficial for multiple reasons. For one, you will be able to act and get the slab repaired before the damage becomes too great. Also, you’ll be able to protect yourselves and your loved ones from having an accident due to the uneven slab. 

Walking on an uneven surface is incredibly dangerous, especially for children and the elderly. Spotting and identifying concrete sinking will keep you alert and help you avoid unnecessary accidents.  

  • Flimsiness 

Even if the slab shows no visual signs of settling, you might be able to feel the difference if you walk on it. Concrete slabs that are settling feel unstable when you put weight on them. Because soil never displaces evenly, when you put your weight on one side of the slab it will feel stable, but the other side will sink lightly when you do the same. 

Once you notice this flimsiness, don’t continue to put weight on the slab if you can. By putting weight on it, it adds pressure against the soil, which is already unstable enough as it is. This accelerates the settling process, so it’s best to be left alone until repairs are made.

  • Strange Smells 

One of the many downsides of concrete settling is that the gap under the slab makes it easy for animals and insects to get under your property. If the gap is significant enough, then there’s a chance that a few animals are using it as shelter or as a tunnel to get somewhere else. 

You might not notice it if you live in a suburban area, but for those that live in a more rural part of town where the air quality is higher, there can be strange smells around your property due to potential animals underneath your slab. 

  • Pooling Water 

When you have one or more settling slabs around your property, the ground becomes uneven. This creates a problem with yard drainage around your home. Whenever water lands on your property, if it has a positive yard grade, the water is supposed to flow away from your home and out to the streets. If your yard has a negative grade, water will flow towards your home and your foundation.

The uneven concrete slabs around your home can create a small crater in which the water accumulates instead of flowing away. You can tell it’s specifically a concrete settling issue when the water only pools around the areas of your home that are covered in concrete.  

  • Void Under the Slab 

When you take a closer look at your concrete, look towards the edge where the slab meets the soil. A good indicator of settling is an opening that leads to the underside of the slab. It’s quite common for concrete slabs to have an opening like this because the soil that meets the slab is exposed more than the soil under the slab. Soil that is exposed to the elements erodes a lot faster, so as the topsoil washes away, it leaves a gap right along the edge of the slab. 

If you do find a void, do not try to lift the slab to see how deep the gap is. Not only is this dangerous because of how heavy concrete slabs are, but also because this could displace the soil further.  

  • Cracks 

Concrete slabs crack for several reasons, but there’s a certain kind of crack that’s specific to concrete settling. When concrete settles, it rarely does so evenly. This means that there’s going to be a side of the concrete that is lower than the other side. When settling, the cracks usually appear from where the concrete begins to slope down and settle. 

This is because a slab that does not have a solid foundation cannot withstand a lot of pressure. Since slabs often settle around the edges, most cracks indicate that settling can be found there.  

What Are the Downsides of Concrete Settling? 

If you’re a homeowner who has mild concrete settling, then you might be wondering if it’s worth doing anything about it now. After all, if you can still walk around your patio and get the car in and out of the driveway, why not leave it for later? 

The problem with not resolving concrete settling, even when it’s mild, is that it can get a lot worse very quickly. There are too many downsides to letting concrete settling get worse.  

  • Car Damage 

Your car is one of the many things that can crack a slab into multiple pieces once it begins to settle. Creating and going over those potholes every time you use your driveway can slowly damage your car’s wheels.  

  • Injuries 

Walking on an uneven path can lead to a wound. With sinking concrete slabs, one wrong step can make you lose your balance and fall. It might not seem important when the settling is barely there, but you don’t want to get to a point where you’re avoiding areas around your home because you’re scared of tripping. 

  • Property Value 

Besides making the outside of your home look less welcoming in general, settling slabs lowers the property value. The worse the settling is, the lower the value. 

  • Inconveniences 

Having a slab sinking problem can be very limiting. Because of the uneven surface, there are many things you aren’t able to do. Setting up an inflatable pool, a basketball net, or placing furniture can be difficult to do on uneven ground. You have a lot more freedom to do as you wish on your property when the ground is even.  

  • Expensive Repairs 

The more that time passes, the more the slabs settle. The more they settle, the more expensive the repairs will be. One settling slab opens the door for more moisture to invade the soil under other slabs as well. Before you know it, a large part of your patio or driveway is suddenly sinking. 

What Should I Do If My Concrete Is Settling? 

Once you’ve seen your concrete, spotted the problem signs, and determined that something needs to be done about the slabs, it’s time to call a professional for concrete lifting repairs. However, repairing settled concrete isn’t as easy as simply filling the gap left by the soil. 

There are very few materials out there that can hold up something as heavy as a concrete slab while still discouraging soil displacement. The only thing that can do the job right and hold up continuously is the polyurethane foam used in PolyRenewal™. 

PolyRenewal™ is a concrete lifting solution in which polyurethane foam is injected into the slabs until there is enough to raise and support the concrete. The reason PolyRenewal™ works is because of the material. Unlike the cement slurry used in traditional concrete lifting methods, polyurethane foam does not displace the soil further because it is lightweight. It’s also impermeable and doesn’t allow water to pass through and damage the soil. It’s the only material in the industry that can do the job as efficiently that never erodes or shifts. 

Polyurethane foam injections for concrete lifting are only available from experts. The tools, materials, and expertise needed to execute this kind of solution can only be found in companies that specialize in this kind of work.

Sinking Concrete Slab


When looking at the deterioration the slabs around your home experience, you might notice that your slabs are not reinforced with rebar. Typically, concrete slabs used for walkways, driveways, pool decks, and other areas of your home are only four inches tall and are not reinforced. 

If your concrete is sinking, then you might be wondering if you should replace your settled slab with one that has rebar. Unfortunately, rebar does not stop a concrete slab from settling. Replacing and repouring a brand-new slab is a lot more expensive than simply leveling it. It’s also a waste of time because you’ll be dealing with the same settling issues in a few years despite the addition of rebar.  

  • What It Does 

Rebar is used to reinforce concrete because it has great compression strength but poor tensile strength. Compression strength means that concrete does not lose despite supporting a lot of weight. Tensile strength measures a material’s ability to resist breaking under pressure. Poor tensile strength is the reason concrete breaks so easily when hit with a hammer: Because the pressure is concentrated in one spot, the concrete cannot take the hit and breaks in half. 

Rebar is meant to increase concrete’s tensile strength by absorbing pressure. The rebar redistributes pressure evenly throughout the slab so that it’s not concentrated on one point. This way, the concrete can take on heavier loads and withstand a lot more.  

  • What It Doesn’t Do 

The reason rebar does not help in preventing concrete settling is because settling has nothing to do with a slab’s tensile strength. Regardless of how much pressure it’s able to withstand, if it doesn’t have a solid foundation, it will sink. Therefore, it’s futile to try to add rebar to the slabs around your house just to avoid settling. If there’s soil displacement, there will be settling. 

What rebar can help with is concrete cracks after there has been settling. If the slab has settled, then there’s a chance it will break apart because it cannot distribute pressure properly on an uneven base. Rebar can help the slab stay strong and not crack. Still, adding reinforced concrete to your home’s pavement is not worth it when you can just use polyurethane foam injections. 

Soil displacement cannot be prevented because it is oftentimes caused by things out of our control. As a homeowner, this can be incredibly frustrating because it means there’s not much you can do to avoid concrete settling. Still, there are things you can do to make sure you’re not accidentally displacing the soil yourself. It would require certain lifestyle changes, but if you want to protect your slab from sinking, it must be done.  

  • When It Can’t Be Avoided 

Soil erosion cannot be avoided when it’s caused by natural events like blizzards, hurricanes, thunderstorms, strong winds, and earthquakes. These events are completely out of our control, and there’s no way to manipulate how the soil in our property shifts in response to these events. 

It’s also impossible to cover up the entirety of our yard to protect it from the weather. During the winter, some snow is going to be able to reach your concrete, meaning it will be affected by the freeze-thaw effect in some way. Even though there aren’t extreme storms in Grand Junction, unless every part of the yard is covered up, there’s going to be some form of displacement.  

  • When It Can Be Avoided 

Despite all this, there are changes you can make around your home to keep your slabs stable for as long as possible. Improving the drainage systems around your yard so that water doesn’t flow towards your concrete is one change that can make all the difference. During the start of spring, make sure your yard drainage systems are kept clear of any ice or debris so that the melting snow has a way to flow away from your home instead of towards your concrete. 

Being extra vigilant about the amount of snow that lands on your concrete to avoid freeze-thaw damage is standard maintenance for outdoor concrete. And although it is not practical to cover the entirety of your yard, you can cover some of the concrete, at least during the winter, to make sure the soil underneath stays as dry as possible. 

Many homes in Colorado are made with a slab foundation instead of a crawl space or basement. If the concrete slabs outside your home can settle, your slab foundation can settle as well. 

Slabs used for foundations are barely any different from the ones laid out across your driveway. They are also typically four to six inches thick and aren’t always reinforced with rebar. One of the few differences is that slab foundation settling can be a lot more detrimental and disruptive than typical slab settling. So much so that some homeowners believe that slab foundations cannot be repaired once they settle. This, however, isn’t true.  

  • How It Settles 

Slab foundations settle for the exact same reasons normal slabs do—soil displacement. Once the slab begins to settle, the entire house is affected. Doors and windows become jammed due to warping frames, cracks begin to appear along the walls and ceiling, indoor flooding becomes a possibility, and pipes and HVAC vents get damaged. 

Slab foundations settling can have severe consequences on a household. Still, just like regular slab settling, there’s no need to replace a foundation. It’s an invasive process that costs more money than repairing the slab does. If your slab foundation is settling, before you decide that it should be replaced, speak to a foundation specialist about getting it repaired first.  

  • How It’s Repaired 

One of the many ways slab foundations are repaired is with the use of slab piers. Slab piers are drilled deeply into the ground until they reach stable soil that does not shift. The piers are anchored to the foundation and leveled out. Because of the piers, instead of loose soil, the house is supported by load-bearing soil that does not cause settling. 

Since the foundation is a slab, it can also be lifted with PolyRenewal™ like regular slabs. Polyurethane foam is capable of lifting loads that are over 120 tons. It can easily lift your settling slab foundation as well, though it’s best to speak to your local foundation expert to see if this method is right for the slab. 

Call Foundation Repair of Western Colorado for Concrete Lifting Solutions 

If you live in Grand Junction, then we can help you even out your concrete and restore it back to its previous stability. Since 2005, Foundation Repair of Western Colorado has been keeping homes safe, beautiful, and intact with ground-breaking solutions and unforgettable customer satisfaction. 

If you’re interested in getting a free inspection, call us or use the online contact form on our website. During the inspection, you’ll get a cost estimate as well as a timeline that details the repairs. Never settle for less and choose Foundation Repair of Western Colorado!

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