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Common Causes of Basement Floor Cracks

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If you notice cracks forming on your basement floor, then this could be a serious cause for concern. Even though the cracks might not seem like a big deal at first, this could be an indicator of a major problem elsewhere in your home. In this guide, we look at the common causes of basement floor cracks, the problems they can cause, and why you should schedule basement floor crack repairs as soon as possible.


The good news is that in most instances, cracks that form on your basement floor are nothing to worry about. For instance, it’s normal for cracks to form soon after your home’s foundation is built. These are known as non-structural settlement cracks. Settlement occurs when the ground beneath can’t support the overall weight of the structure due to instability. Soil movement occurs in the top layers, and when the concrete slab eventually settles after this movement, cracks may form. Some cracks may be more serious as they indicate damage to your foundation. The settlement process doesn’t just happen in a newly built home.

This process can keep happening over time, and as your home ages, wear and tear can lead to the formation of more cracks. The floor may start to crack as it naturally dries out. This usually leads to the formation of hairline cracks, which aren’t pleasurable to look at but are thankfully not linked to structural problems. Keep in mind that the ground beneath your home can shift under the weight of the whole structure. This is natural movement, but tree roots can also cause the shift to occur, resulting in settlement. Settlement can also cause cracks in the walls and create a slight slope that prevents doors and windows from opening or closing properly.

Improper Drainage

Poor drainage around the foundation can be triggered if the soil is not graded properly. As a result, water will have nowhere to go. A serious build-up of water results in increased hydrostatic pressure, which causes the foundation and the basement floors to crack. To prevent the problem from getting worse, you’ll need to enlist the help of professionals to solve drainage issues and reduce hydrostatic pressure.

Professionals will start by making sure your landscape is well-graded and the downward slope leads away from your home. They’ll make sure your gutters and downspouts are working properly to direct water away from the foundation. Additionally, they can install drainage around the perimeter, as well as a sump pump system. This prevents hydrostatic pressure from pushing on the foundation and affecting your basement floors. When this is taken care of, the professionals will be able to tackle the issue of basement floor crack repairs.


Heaving is a more serious problem than settlement issues are. Instead of minor soil movement, the shifts beneath your home are more pronounced and can result in major misalignment issues. You may notice that a section of the floor is more pushed outwards, creating a large crack between the two uneven sides. However, the soil is not the only thing that can apply outward pressure to your basement floors. Tree roots that spread wide beneath your home can also put pressure on the foundation, causing the concrete floor to crack and create cracks. The most common type of heaving is frost heave, which is a phenomenon linked to frozen soil. This usually happens in winter when the soil beneath the basement freezes and then thaws when temperatures get warmer. Remember that freezing causes contraction, and when the soil thaws, it tends to expand again. This causes a shift directly beneath the foundation of your home. This freezing soil or frost heave results in cracking in the basement floor.

Frost heave can be prevented by replacing the soil around your foundation with gravel or fill sand. You can also enlist the help of professionals to insulate your foundation and ground around it. This prevents the contraction and expansion caused by freezing weather. A new sump pump will be useful, as the presence of water underneath your foundation during the colder months can make the problem even worse if the temperatures are low enough to freeze.


Concrete basement floors are naturally prone to cracking as the drying process occurs. According to Bob Vila, concrete requires 28 days to fully dry out, though you should be able to walk over the surface after 48 hours or so. Initially, the concrete is mixed with water to bring out the desired properties of concrete. After the basement floors are laid, the water in the concrete begins to evaporate. The rate of evaporation depends on the temperature in the basement. The temperature has to be just right; if the temperature is too high, the water evaporates quickly. This rapid shrinkage results in cracks. On the other hand, if the temperature is too low, the moisture in the concrete can freeze, creating shrinkage again, which leads to cracks. The good news is that cracks caused by shrinkage are not typically a sign of structural damage.

Answering Common Questions

Now that you’re aware of the common causes of basement floor cracks, you may have a couple of questions. Luckily, we have answers for you!

Why Is It Necessary to Repair Basement Floor Cracks?

Why should you be concerned about what causes basement floor cracks, and why are basement floor crack repairs necessary? Usually, it’s the larger cracks that can lead to all sorts of problems. Large cracks can invite more water and moisture into the basement. The weight of your home adds pressure to the soil beneath your home, and this pressure causes water to seep up, and if there are cracks, the moisture ends up making its way into your home. This is why most basements end up with a damp and musty smell. The presence of moisture can lead to all sorts of problems, such as mold growth. Additionally, cracks in the basement floor create the perfect nesting place for insects and other pests that live in the soil around your home. It’s important to prioritize basement floor crack repairs, as this can lead to intense structural damage.

What Are the Different Types of Basement Floor Cracks?

Hairline cracks are the least problematic cracks when it comes to basement floor repairs. It’s often not necessary to repair these cracks, though you may want to, as they can be aesthetically unappealing. However, you’ll need to call the professionals to seal any cracks that are 1/8-inch or wider. These cracks can let moisture and radon gas seep into the basement. According to Bob Vila, cracks in your basement floor that are wider than 1/8 inch must be sealed to prevent unpleasant smells, moisture, and soil-derived gasses from seeping up from the ground. If you’re not sure if the cracks you’re dealing with are a cause for concern, you can request a professional evaluation of your basement floor cracks.

The more you understand about basement floor cracks, the more you’ll know how to resolve the issue. This ensures that your home’s basement remains a healthy and safe place. Basement floor crack repairs can be an essential part of remodeling or finishing your basement. For the best results, it’s important to hire professionals that specialize in basement floor crack repairs. Remember, fixing the cracks in your basement floor is easier if you catch them early. Let our waterproofing pros take care of the issue for you. Call us at A-Proseal today!

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