Foundation Cracks – What You Need to Know

Most foundations in the U.S. are constructed with poured concrete or concrete masonry. These materials tend to shift and cause a foundation crack.

When a foundation crack appears as a widening, horizontal fracture or as a jagged, stairstep split in the mortar, it is time to worry. Thin, vertical cracks are usually benign, while horizontal and stairstep cracks typically suggest compromised ground conditions.

Positive identification of the type cracked foundations of cracks you have, and knowing what steps you can take to combat them further, will help you find the cause of the foundation cracks.

Primary Causes of Foundation Cracks

Every crack is for a reason and indicates something about the foundation and the structure itself. These are the most common reasons for foundation issues.

Elastic Soil Leads to Settlement

Almost all of the issues people refer to as settlement are caused by elastic soil. The house is making creaking noises.

A house exerts a lot of pressure on the ground. Different types of soil can coexist under the house, which can cause differential settlement, because of the rain, hot and cold temperatures, and the soil contract under the house. Different parts of the home can settle into the ground at different rates.

Different types of soil have different problems. Clay soil can shrink dramatically in dry conditions, causing more drastic settling of the foundation and home, and creating more extensive problems.

There isn’t much to be done about this kind of settling, which is reassuring as the most common cracks are not causes for alarm.

There is a 10-minute video on the Homebuyers School website.

Poor Drainage Can Cause Oversaturated Soil

No matter the amount of rain, drainage is an essential part of your foundation. Water can build up around your foundation if you have poor drainage.

The only universal solvent is water. Water can ruin things. If you don’t let it stand against your foundation, you will inevitably have problems that need attention.

Tree Roots Impact The Ground’s Moisture

Most people think that a tree’s root system pushes up on a foundation, but it’s actually not. The downward settlement of the foundation is caused by the drying of the soil, which causes it to compact.

A homeowner with a tree close to the foundation needs to know how that tree is affecting their home.

Foundations Lose Durability With Age

Your foundation will become more prone to issues as it ages. There may be issues related to when your foundation was created. A foundation that was built in the 1920s may not have the correct material or may not have the correct reinforcement.

If you know the cause of your foundation’s age, you will be able to make better decisions about how to fix it.

Identifying the Common Types of Foundation Cracks

The way brittle material cracks can affect the action needed to be taken. It will be the difference between panicking in the face of expensive repairs or calmly monitoring something that may not be all that serious.

If there are cracks in the same spot on both the interior and exterior surface, that is an indication of a serious issue. The width of the crack is another consideration. The bigger the problem you have on your hands, the bigger the crack is.

Stairstep Cracks

The most serious stairstep crack can be found in the foundation of your home or the exterior walls. The crack follows the mortar between the bricks and makes a stairway.

The cracks in the basement show the pressure on the wall. The wall may have an inward bow.

The differential settlement may cause these cracks.

It is not a good idea for a homeowner to take a chance on a stairstep crack in the brick wall of their home. If a stairstep crack is found, it should be attended to sooner rather than later.

Horizontal Cracks

Not as bad as stair-step cracks, horizontal cracks are serious concerns. The location of a horizontal crack is a large part of the cause of this type of crack. The ground at the bottom of the basement does not freeze as much as the ground at the top of the basement, which may be related to the cracks in the basement ceiling.

Cracks above a door or a window are not a foundation issue and are certainly something to monitor, but not a foundation issue requiring urgent attention.

Vertical Cracks

The vertical crack is the least serious of the three types of cracks, it has few problems other than letting in water, which could lead to more serious issues. These are not a cause for alarm because they are related to concrete shrink.

Like any crack, a vertical crack needs to be noted and inspected from time to time, as a vertical crack that grows wider is an indicator of a bigger issue. As it mounts over the crack, the CRACKMON 4020A Heavy-Duty Building Foundation Crack Monitor allows for accurate tracking of its size and width.

Other Indicators of Foundation Issues

You can find foundation cracks in a basement or crawl space. There are signs a homeowner can look for that indicate a foundation crack or other issue that needs to be fixed. There are more common indicators of an issue.

  • There are cracks at the corners of the doors and windows.
  • Windows begin sticking
  • The doors are swinging open or closed.
  • Cracked or loosened floor tiles
  • The chimney leans towards or away from the house.

It is important to conduct regular checks to ensure the longevity of your home.

  • You should look for cracks in walls and doors that weren’t there the last time.
  • Look at the ground outside. There are puddles in places where water used to be.
  • Is your floor sagging? If your kid’s Hot Wheels didn’t move on their own but now one place in the dining room can be used as a drag racing strip, you may have an issue.

You can find a comprehensive list of things to examine in your annual or semi-annual home check-up with a cursory web search.

Finding the Right Repair Solution

It’s best to consult with a professional for major foundation issues. If your basement wall is sagging inward, you have stairstep cracks running up and down the length of it, and water is leaking in, you are most likely unqualified to fix the issue with your tools and video.

Minor issues can be solved by the do-it-yourselfer. Smaller and less serious cracks can be repaired with the Radon Seal Concrete Foundation Crack Repair Kit.

This Old House has hours and hours of information about all kinds of repairs. Tom is walking through a crack repair in a video.


It’s a good idea to notice any cracks in your walls or foundation. Even though there are harmless cracks, inevitable cracks, and severe cracks, the fact remains that any foundation crack can indicate serious, expensive problems, meaning you shouldn’t ignore them.

If you find a crack in your home, it’s a good idea to check it out further. The sooner you attend to it the better.


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