Cracks on the basement floor might cause homeowners to panic. The good news is that most basement floor cracks are natural and do not require repair. However, some basement floor cracks can allow water, dampness, and toxic soil vapors to enter (including radon). This guide can help you understand what sealing the cracks in your basement concrete floor means and how to fix and repair them.

What Causes Basement Floors to Crack?

Cracks in a home’s foundation are fairly prevalent after it is built. The cracks are usually natural, non-structural settlement cracks. However, there are other reasons why a foundation cracks, including home settling, concrete shrinkage and curing, stress, and faulty construction.

What About Your Drainage?

Water can pile up and impose pressure (referred to as hydrostatic pressure) on the foundation if the soil around it is inadequately graded or there is incorrect drainage. There are easy things you can do to relieve hydrostatic pressure and prevent basement cracks.

Types of Basement Floor Cracks – And What They Mean

#1. Heaving cracks indicate a larger problem that must be addressed.

It is a cause for alarm when a basement floor crack is paired with heaving. The presence of heaving indicates that the earth beneath the basement floor is spreading. Heaving is very common in clay soil locations. Wet soil produces enough pressure to lift and break a concrete slab floor.

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#2. Concrete floors with cracks and sinking should be straightened.

When a foundation settles, the concrete slab can split and the less supported portion of the slab lowers into the depression. The uneven surface that results can be a tripping hazard.

#3. The basement wall and floor gap should not be sealed.

Water seepage is a common problem in the basement where the walls and floor meet (called the cove joint). When the concrete walls and floor are poured during construction, a little gap is left between the floor and the walls.

#4. Hairline cracks do not require repair.

Small cracks in the basement floor are often caused by shrinkage when the concrete dries, which pulls the concrete apart. Depending on how quickly the slab dries and how humid the basement is, these cracks can appear up to a year after the basement floor is poured.

#5. 1/8-inch or wider cracks should be sealed.

These slightly broader cracks, like hairline cracks, are most likely the result of shrinkage and do not indicate a significant foundation concern. However, even small cracks in the basement floor can let water, mildew, and radon into the basement.

#6. Spalling or flaking is unsightly but does not necessitate repair.

It can happen if the concrete mix is excessively moist or has not been adequately cured. The water evaporates, causing the top layer of the concrete to peel off. Although concrete spalling is unsightly, the slab is likely to be in good condition.

Sealing Cracks In Basement Floor

Concrete floors provide a strong, long-lasting foundation in your basement or garage. This does not imply that they are unbeatable. However, movements in the earth, dampness in the ground, and pressure from automobiles and other heavy items can cause fracturing in the floor over time. Sealing cracks in the basement floor is quite straightforward when they are new and small. However, older concrete floors that have not been regularly maintained will require extensive work to restore them to their original condition.


Whatever the age or condition of your concrete basement floor, you should always seal it once it’s finished. Sealing cracks in the basement floor will prevent further water, chemical, and pressure damage. Sealing an old, beaten-up concrete basement floor, on the other hand, requires a little more effort than sealing a new concrete floor. Let’s go over the steps in each situation.

Sealing Cracks on a New Basement or Garage Concrete Floor

You cannot seal a newly laid concrete floor right away. Concrete cures in roughly a month on average. Sealer should be applied only after the material has been completely set in place. Waiting this amount of time will provide the best conditions for basement or garage floor sealing.

So, after the fresh concrete has been cured for 28-31 days, it’s time to seal the floor. In this regard, you have numerous material alternatives, including epoxy, acrylic, siloxane, polyurea, and others. The cost, lifespan, and appearance of these sealing materials vary. This long-lasting substance produces a stunning finish that can last for more than 25 years.

Sealing Cracks in an Old Concrete Basement Floor

When the time comes, the sealing technique for cracks in an older, broken-down concrete floor is the same as the sealing process for a new floor. However, extra effort must be made ahead to repair and prepare the floor. For the seal to be effective, the original floor must be restored fully and smoothly again.

As a result, before the sealing procedure can begin, any existing, old seal must be removed and the floor properly cleaned. The most effective way is to use a strong floor grinder. This will remove any remaining sealer as well as excess oil, dirt, and debris from the surface while smoothing it down.

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After that, you’re left with nothing but bare concrete. Every gap and crack must be filled and smoothed down with epoxy crack filler. When everything is dried, your old floor will look a lot nicer than it did previously. You can use whatever sealer you choose to make it as nice as new. From here, the procedure is the same as explained previously.

Repair Cracks In Basement Floor

Repairing cracks in your basement floor does not have to be a tough task. This step-by-step guide will teach you how to repair cracks in the basement floor.

Most basement floors are composed of concrete, and while it is a highly durable material, a crack repair will be required from time to time. The good news is that when planning a basement remodel, most cracks repair in the basement floor can be achieved with a few tools and materials.

Before beginning treatment on the surface, it is vital to determine why the fracture began in the first place. The most common cause of a basement floor crack is wear and tear. However, if you discover a significantly cracked area or a crack that runs parallel to the foundation, the problem could be caused by structural damage.

Beginning by removing any debris, such as loose concrete chunks that may be stuck within the fissure. To make the job easier, use a wire brush and a shop vacuum. Check that the surface is clean of dust, grease, and filth.

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Apply a concrete fix to the fracture, being careful not to leave any gaps or uneven regions. Using a putty knife, smooth the patch. Wait for the first coating to dry before applying the second coat if the crack requires a second patch. Allow the concrete fix to dry for several days before sealing it. Certain cracks may be caused by structural deterioration and necessitate the assistance of a professional engineer or foundation specialist.

How To Fix Cracks In Basement

After you’ve identified the issue, it’s time to fix basement floor cracks.

Step 1: Determine the source of the problem.

Use the descriptions above to figure out what created these cracks. Most of the time, it is something natural, such as the house settling. If it’s heaving, you’ll need to call in the professionals.

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Step 2: Take out any loose pieces

Begin by removing larger pieces of junk with your fingers or by using a wire brush to get the piece out. A shop vac is frequently the best solution to fix loose material from basement cracks.

Step 3: Taper the crack

Now that the gap has been cleaned of dirt and debris, you must create a wide enough area for the concrete sealant to penetrate and fill the hole. There are several approaches to this. You can complete this procedure by hand by creating a V-shaped opening that goes along the crack using a hammer and chisel.

Step 4: Remove any debris or dirt from the cracks.

Chiseling or grinding out the fracture will produce a significant amount of dirt and debris, which must be cleaned before applying the fix to the cracks in the basement. Remove any dirt from the fracture with a brush and then vacuum it up with a shop vac. Make sure you collect everything since any debris left in the fracture will prevent the concrete repair from bonding properly.

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Step 5: Use bonding adhesive

Brush bonding adhesive on the crack and allow it to dry completely. You might be tempted to skip this step and start applying the concrete fix right away. This would be a blunder.

Step 6: Put on the concrete patch

Apply the concrete repair in layers to ensure a patch that penetrates deep into the crack and is thick enough to withstand any hydrostatic pressure from moisture in the soil below.

Step 7: Allow it to dry

Allow the patch to dry before applying foot traffic, water, or paint to it. Most concrete patches cure in three days or less, but check the box for particular dry times. Remember that letting the patch dry correctly is critical to achieving optimal strength.

How to Fix Hairline Cracks in Basement Floor

Fixing hairline cracks smaller than 1/4-inch wide on a basement floor is more difficult because it can be difficult to force the concrete patch inside the fissure. Use a liquid concrete repair product that is thinner and hence more capable of entering inside and adapting to the fracture.

Concrete Cracks In Basement

If you have concrete surfaces in your basement, you may have noticed cracking along the flooring or even on the walls. Cracking in concrete can occur for a variety of reasons. Learn more about the origins of these basement cracks so you may be ready the next time you contact a concrete repair professional. Here are four of the most common causes of basement concrete cracks.

What Causes Basement Concrete Cracks?

#1. Laying the groundwork

Concrete slabs and foundations commonly settle due to unstable soil beneath the structure. The weight of your home on changing ground can cause the concrete to shift, resulting in cracks and gaps in the floors and walls, particularly at corners. Doors and windows may appear unequal as well. If this occurs in your home, you should seek concrete repairs as soon as possible.

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#2. Concrete shrinkage

Concrete is made of cement and water, and it must be poured and hardened to form a solid surface. Shrinkage is typical; however, the amount varies according to the temperature of the room. When the temperatures in your basement are too volatile, you may see cracking because excessive heat and cold interfere with curing. This damage is more likely to occur on doors and corners.

#3. Spalling

Spalling appears as flaking on the concrete’s surface. It’s frequently caused by the mix becoming overly saturated during the pour. Excess water rises to the surface, causing a weaker layer at the top. Even if it appears unappealing, it is usually harmless, and the surface’s structural integrity is unaffected. A concrete repair professional, on the other hand, can assist in repairing this repair for a more appealing floor.

#4. Moisture problems

Water can develop considerably wider fissures in your concrete if it gets into minor cracks. Wider cracks can compromise the strength of your foundation. Consistent moisture in those cracks will eventually lead to mold and mildew problems.


Whatever type of crack you have on your basement floor, you should always take precautions to seal the damaged area before it becomes a bigger problem. The cost to repair or fix concrete cracks in the basement floor ranges from a few hundred to tens of thousands of dollars. If you are unsure about diagnosing or repairing your broken basement slab, get professional assistance. Taking care of these cracks now might save you a lot of trouble and money later.

Frequently Asked Questions

Is it normal to have cracks in basement floor?

The short answer is that fissures in concrete flooring are common, if not unavoidable. As the mix dries and the water evaporates, microscopic fissures will form in the concrete. Your concrete basement floors may crack over time due to consistent settlement.

Should I worry about cracks in my concrete floor?

Cracks in your floor are generally nothing to be concerned about. The only time you should be concerned is if the fractures begin to change vertically, indicating that there is some settling going on.

When should you worry about cracks in foundation?

When you notice cracks that are wider than 1/10 inch, you should be concerned. cracks that are wider at one end than the other. Cracks that grow in size over time.

How can you tell if a crack is structural?

Structural fractures arise as a result of inadequate construction sites, overloading, or poor soil bearing, as the term implies.

The following are symptoms of structural faults in your foundation:

  • Cracks in the stairwell.
  • Foundation slab or beam cracks
  • Wide vertical fissures at the bottom or top.
  • Cracks that are 1/8′′ wide.

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