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Guide to Foundation Cracks: Things to Know, Types of Cracks, and Repair

Why Is There a Crack in the Basement Wall?
Whether you’re a DIY type of person or rely on professionals, you need to know how to take care of your home’s foundations. After all, it’s the most critical part of every construction.
Cracks are the number one foundation problem, and knowing how to spot them, how the repairs are performed, and what types exist are crucial for every homeowner.
In this entry, you’re going to learn more about the basics of foundation cracks.

Types of Cracks

There are two types of foundation cracks to consider. They might look identical at first glance, but they are actually caused by different things and carry different risks altogether.
  • Wall shrinkage foundation cracks
  • Wall settling cracks

Wall Shrinkage Foundation Cracks

Usually, these cracks are “uniform” in terms of width but can sometimes be V-shaped. Wall shrinkage cracks are wide at the top but get smaller moving downward. They stop before they reach a wall’s bottom section.
Wall shrinkage foundation cracks are found beneath basement windows, near step-down areas, above doors, and on long walls (especially if they don’t feature control joints).
Wall shrinkage cracks are no more than 1/16” in width. They have a hairline-like appearance and are random, sporadic and discontinuous.
Benign as they look, these cracks can serve as entry points for water, leading to more damage and further foundation issues. Sometimes, though, they are harmless.


As concrete cures (chemical reaction caused by various factors), internal stress is inflicted onto the wall. Cracks occur here as internal stress relief. But what are some specific causes of wall shrinkage?
A poor concrete mix can result in this crack type. Even if there is proper steel reinforcement, the concrete needs to be of decent quality to properly support the foundation. However, without steel reinforcement, even the best concrete mix will fail to provide a proper foundation.
To an extent, concrete shrinkage is expected due to seasonal changes (concrete expanding and contracting). A good mix and carefully-placed steel reinforcement should help keep any crack-in-foundation type of a problem at bay.
Brick walls have also been known to cause wall shrinkage foundation cracks. Although brick walls won’t shrink, they will expand indefinitely, putting a lot of strain onto a foundation wall.


No, they don’t look nice. Still, shrinkage cracks don’t require remediation or monitoring. As mentioned earlier, though, wall shrinkage foundation cracks can cause water entry. To fix this, the crack is chipped out and filled with a sealant compound. Polyurethane foam, epoxy, masonry patching compound, and other sealants can be used here.

Wall Settling Cracks

Wall settling cracks are also known as vertical wall cracks. They are often found on poured walls. These are relatively wide towards the bottom, becoming wider and longer as time passes. Wall settling cracks usually occur not long after the wall’s construction is done. They can spread down the affected surface and can easily cause water infiltration. Wall settling cracks will increase over time until they get to at least ¼” in size.
A wall settling crack can reach the bottom of a wall and then cause cracks in basement floor surfaces, so they are pretty dangerous for the foundations.


Wall settling cracks occur as the foundation wall in question is settling into place. If the foundation footings are poorly prepared, the foundation will move, and wall settling cracks will appear to compensate for the extra pressure. Correctly adding steel reinforcement can help alleviate this problem.
As a result of sub-grade settlement, hydrostatic pressure increases, which can cause uneven stress factors, leading to cracking.
Although they are called vertical cracks, sometimes, wall settling cracks occur diagonally. This may occur as a result of a wall being exposed to frost. Additionally, excessive point loads, expansive clay soil, and tree/shrub roots can also cause wall settling cracks.
Strangely enough, wall settling cracks can often appear horizontally. At the mid-wall point, horizontal wall settling cracks are most likely a result of heavy equipment damage or premature backfilling. At a wall’s base, wall settling cracks are probably the result of earth loading, especially near dense/wet soil.


The foundation is first stabilized using driven steel pins. These pins are seated on bedrock, in the proximity of the foundation. Then, with room for leveling control, repairs are performed. Each pin can cost more than $1,500, so hiring a professional is the best way to go here.

Identifying the Problem

Although we’ve mentioned the repair methods for both foundation crack types, let’s tackle the reasoning behind these repairs. The first step with fixing a crack in basement wall is identifying the necessary steps. This boils down to three categories.
The first category is where the foundation cracks are cosmetic. In other words, there is no need for further repair, although you can go out of your way and fix things for cosmetic purposes.
The second tier of observing foundation cracks are instances where monitoring is warranted. This boils down to measuring the cracks over time and checking for potential water infiltration. As long as the cracks don’t grow in width/length and as long as there is no water infiltration, no action is necessary.
The third and final tier of identifying the foundation wall crack issues is where the cracks are significant, progressing, and need tending. Unless you’re a professional or have been working with foundations for a long time, referring to the experts is advised with the third tier. Remember, the problem isn’t purely cosmetic on this level, and the most significant danger isn’t water leakage but structural damage and collapses.

Dealing with Foundation Cracks

The first step in dealing with foundation cracks is classifying them. Use the knowledge gained from this entry to put a label on the crack. From there on, you can prioritize the resolution of said problem and proceed accordingly. Wall shrinkage foundation cracks are usually cosmetic (although they may not be), while wall settling cracks tend to be much more severe. If you are unsure about any aspect of foundation cracks, refer to the experts, to be safe.

Paul S

Paul has more then 20 years in basement waterproofing and plumbing projects experience. Looking for an advice from an expert plumber? Make sure to read Paul's articles about residential waterproofing and plumbing projects in Toronto.

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