Foundation Crack Repair: Frequently Asked Questions

We get many different questions in regards to basement wall cracks and solutions for preventing and fixing them, so we thought that we would address these FAQs in one location.

What causes cracks in basement walls?

There are a number of issues that can lead to foundation wall cracks, some of which include:

  • Exterior drainage system problems (Clogged gutters, clogged drainage pipes, poorly sloped landscapes, etc.)
  • Bowed foundation walls from exterior pressure
  • Old or weakening concrete
  • Abnormal changes in soil saturation – both heavy rains and droughts
  • Poorly designed foundation walls or old concrete block walls.
  • Sinking foundation floors or walls
  • Exterior tree roots

Is there a big difference between vertical and horizontal cracks in your foundation?

Yes. This is often one of the first questions a professional will ask you about any cracks in your basement walls. Vertical wall cracks and horizontal wall cracks are caused by very different factors and it is important to understand them.

Vertical Cracks in Foundation

Vertical or diagonal cracks in your basement walls are not as serious as horizontal cracks but can still lead to water leaking and flooding issues. Vertical and diagonal cracks are typically caused by your basement concrete foundation walls shrinking as it cures. These cracks more commonly occur at weak points in your foundation wall, like at the edge of a window or drilled hole in the concrete. If the cracks are vertical or diagonal, you would expect them to be mostly small and minor, and they are often referred to as hairline cracks.

As with all wall cracks, they will continue to grow and worsen over time, and even small amounts of water leaking through small cracks can lead to hard-to-manage mold and mildew growth. It is still a good idea to have a professional evaluate the cracks to ensure it isn’t a more serious issue like uneven foundation settlement.

Horizontal Cracks in Foundation

Horizontal cracks in your basement walls are caused by exterior pressure on the sides of your basement’s foundation, and the foundation’s inability to manage the pressure without bowing. They are a serious issue and should be addressed sooner rather than later, as they are a warning sign of complete foundation wall failure.

That obviously is cause for concern, as the safety of your home and its occupants will be at risk. Horizontal cracks typically require repair of your basement’s foundation, which requires a trained and professional service provider to evaluate and determine an ideal solution.

Are basement wall cracks normal?

Absolutely. It isn’t that your basement is crumbling apart – cracks are a normal occurrence in basement walls. It is just important to know if the cracks you are seeing are minor or serious.

Vertical cracks are more common than horizontal cracks and will appear at openings or holes in the foundation walls, such as at the corners of windows or the opening to a gas line. Older homes are more likely to develop cracks in the basement due to changing exterior soil pressures and outdated methods for building foundation walls. Newer homes with basement wall cracks often are formed as a result of exterior drainage or landscaping problems or poor building design. Also concrete is a tricky material to work with. It cracks very easily and even brand new foundations can be susceptible to cracking.

Do DIY basement crack injections work?

There are many products that you can use to fill up and seal cracks to prevent moisture and dangerous gasses like radon from entering your basement. Most of these solutions are of a high quality and can be effective at stopping leaks, but they don’t always fix leaks for good.

You should know what likely caused the cracks in the first place and if there are other underlying issues with the foundation walls of your basement that may be causing bulging or bowing. If the crack is still growing, or if something is causing new cracks to develop, crack injection solutions can only do so much to prevent moisture and gas leakage.

If this is the case, other repair methods may be necessary in addition to crack injection, like wall plate and earth anchors, steel I beam reinforcements, wall straightening, and block wall rebuilding. These are typically not DIY methods and should be left to a trained professional who will not only do a good job but can also provide a warranty with their work.

Every case is different, and it often requires a trained eye to determine the causes both big and small that are causing leakage in the first place. We would recommend that you have a professional waterproofing company like StayDry® evaluate your basement before spending money on DIY solutions that might only work for a short period of time.

Epoxies vs. Polyurethanes: Which is a better material for foundation crack repair?

Both are great solutions designed to plug up cracks in foundation walls. They just work in different ways and are applicable for different types of foundation wall cracks.


These are good for addressing vertical or diagonal cracks in your wall. The cracks should be small, typically less than a quarter of an inch thick. After being injected, the Polyurethane solution expands many times its original volume to fill every tiny crack and crevice to prevent water from leaking through the crack.

While polyurethanes stop most water from leaking through vertical and horizontal cracks, they don’t always stop all water, especially if the crack is still active and constantly shifting. A dry well may also be necessary to catch all water leaking from the crack and to avoid mold and mildew issues that can arise from even small amounts of water.


These are primarily used for horizontal cracks in a foundation wall. They do not expand like polyurethane solutions and take a long time to cure. They are very strong, and are designed to not give or be flexible like polyurethanes. They can also only be applied on a completely dry surface, and should only be applied after it is known that the foundation wall will no longer move or change shape.

It is important to note that epoxy solutions for horizontal cracks are used after foundation wall repair methods such as installing foundation anchors, as the epoxies alone will not fix long term water flooding and foundation problems associated with horizontal cracks. As mentioned earlier, if you see horizontal cracks in the walls of your basement then there is likely a structural problem with your basement’s foundation and you will need the help of a professional to diagnose your foundation and determine solutions that best meet your specific situation.

How can I tell if the crack is spreading?

When you first notice a crack, it isn’t always clear how long it has been there or if it has grown slowly or rapidly over time. We recommend using a pencil to mark the end points of the crack and checking on it regularly. This can be valuable information not only for you but for a professional when they are determining a system of repair.

If you notice a crack, check other areas of the basement for similar cracks. They can often be found near pipe lines, window frames, and other openings in your basement walls. Like a crack in your car windshield, it is best to fix cracks soon after noticing them as they will continue to grow and have more damaging effects on your basement.

Contact Us For Your Free Evaluation

The StayDry® team has 100+ years of experience with basement waterproofing, crawl space repair, wall repair, and mold control. Give us a call or fill out the form here and we’ll call you back.

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