Basement and Foundation Floor Cracks

Basement or Foundation Floor Cracks can be a cause of major concern for home and business owners. The good news is most basement or foundation floor cracks are normal and do not need to be repaired. However, some cracks in a concrete floor can let in water, moisture, and dangerous soil gasses (including radon). We want to provide the following information to help you understand what the cracks in your basement or foundation floor mean and whether or not they should be repaired.

Why Do Concrete Floors Crack?

It is very common for cracks to form in a home or business’s foundation after it’s built. Most times the cracks are normal (non-structural) settlement cracks. However, there are several other reasons why a foundation cracks, such as settling of the structure, concrete shrinkage and curing, stress, and poor construction.

crack in concrete wall

How Is Your Structure's Drainage?

If the soil around the foundation has not been graded well or has improper drainage, water can build-up and put pressure (referred to as hydrostatic pressure) on the foundation, causing it to crack. There are several simple procedures a home or business owner can take to relieve hydrostatic pressure and help prevent foundation or basement cracks.

It is Important To Improve Drainage Around a Structure:

  • Always make sure the landscaping is properly graded and slopes away from the foundation.
  • Keep all gutters clean and in proper working condition. Install gutters and downspouts if they do not exist.
  • Make sure the downspouts extend away from the structure to keep them from draining water too close to the foundation walls.
  • Consider adding an interior perimeter drainage system and a quality sump pump system in any basement.

If you have one or more cracks in your foundation or basement floor, determine the type of crack and what might be causing the crack in order to figure out how to best solve the problem.

leaves in gutter

Types of Basement Floor Cracks and What They Mean

1. The upward movement of a foundation or slab is a sign of a bigger problem and needs to be addressed quickly.

The upward movement of a foundation or slab Is referred to as “heaving” and is common where there is clay soil. When a basement or foundation floor crack is combined with heaving, this is a serious cause for concern. Heaving suggests that the soil beneath the basement or foundation floor is expanding. Heaving is most common in those areas with a high concentration of clay soil. When the soil becomes wet, it creates a pressure strong enough to lift and crack a concrete slab floor.

What Should A Home or Business Owner Do?

Call a professional (and reputable) foundation repair contractor. They can evaluate the problem and provide a studied recommendation for a solution to the problem.

2. Leveling needs to occur on concrete floors with cracks that show sinking symptoms.

Settlement causes cracked, uneven concrete basement floors. When a foundation settles, the concrete slab can crack and the part of the slab that is less supported will sink into the area of depression. The resulting uneven surface can create a hazardous tripping condition.

What Should A Home or Business Owner Do?

A Concrete basement or foundation floor that is uneven should be leveled whenever possible. Some professionals use a high-density polyurethane formula to permanently lift and stabilize a sinking concrete slab. In this process, penny-sized holes are drilled into the slab and a structural-grade polymer is injected into the void. The polyurethane material expands, lifting and leveling the slab.

3. If there is a gap between the basement wall and floor, it should not be sealed.

Water seepage at the cove joint is always a common problem. At the point in the basement where the walls and floor meet (called the cove joint) a common problem develops where water seepage can often occur. Typically, during construction, when the concrete walls and floor are poured, a small gap is frequently left between the floor and walls. When the level of the groundwater rises, and the soil becomes saturated, hydrostatic pressure forces water through the cove joint.

What Should A Home or Business Owner Do?

The sealing of this gap is not recommended since the sealant can often crack. The most effective solution to keep water and moisture away from the cove joint with an effective foundation or basement waterproofing system (accomplished with an interior drain tile and a sump pump), which helps relieve the hydrostatic pressure.

4. The basic hairline crack does not require repair.

Hairline cracks are caused by shrinkage when concrete dries. Small cracks in a basement floor frequently result from shrinkage as the concrete dries, which pulls the concrete apart. This type of crack can be revealed up to a year after the basement or foundation floor is poured, depending on how rapidly the slab dries and the humidity level around the area of the slab.

What Should A Home or Business Owner Do?

Typically, there is no need to do anything. Hairline cracks in the slab flooring are superficial and do not typically require repair. If you are worried about how they look, you can cover the concrete with a foundation or basement flooring (i.e. wood-look plank flooring or carpeted flooring).

5. If a crack is 1/8-inch or wider, it should be sealed.

All Cracks 1/8-inch or wider should be sealed. Similar to hairline cracks, these cracks that are slightly wider and are likely the result of shrinkage, and are not typically a sign of a serious foundation issue. However, even the smallest of cracks in a foundation or basement floor can allow water, moisture, and radon to enter and, therefore, should be sealed.

What Should A Home or Business Owner Do?

Any crack wider than 1/8-inch should always be sealed to help keep water, moisture, soil smells, and radon gas from seeping through the foundation or basement floor.

6. There are some ugly eyesores that also do not require repair.

Spalling (the flaking or peeling away of small particles of the cement paste from the near-surface of the finished slab) concrete is unattractive, but it usually is not a cause for concern. It often occurs when the concrete mix is too wet or has not been properly cured. The water evaporates and loosens the top layer of the concrete, causing it to flake off. Concrete spalling is not attractive, but the slab is still, typically, in good shape.

What Should A Home or Business Owner Do?

Do not try to hide the problem with paint. Usually, the surface of the floor will keep flaking and when it does, it will likely take the paint off as well. An owner might want to consider concrete resurfacing, as an alternative, to make the concrete similar to new and also to prevent further spalling. Another option to consider is installing waterproof flooring over the concrete.

If you would like a professional evaluation of the floor cracks in your basement or foundation, or if you are exasperated with water intrusion issues in your home or business, contact us for a basement or foundation crack repair specialist! To find a foundation repair specialist in your area, don’t hesitate to contact us today for your free estimate!