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How to Repair Foundation Cracks

bowing block basement wall

When you find a crack in your foundation, you probably have one of two basic reactions.  Either you panic that your home is no longer stable, or you shrug it off as routine settling.  I’d suggest avoiding these extremes, and aim for the grey area between them; foundation cracks shouldn’t be ignored, but they’re not usually an immediate threat either.  

Yes, all homes settle. It is common for foundations to develop cracks.  Settling and cracking can be the results of natural forces: changes in weather, in humidity, gravity (the weight of your home), and erosion are a few of the most common influences.  But just because it’s a natural occurrence doesn’t mean you can dismiss it.  Once a crack forms, it can spread and/or widen.

Acculevel has been repairing foundations for Midwestern homeowners since 1996.  A family-owned and operated company, we have restored strength and stability to tens of thousands of homes.  We want you to understand the types of cracks you may see in your foundation, and know what types of repairs are the best method for each one.

In this article, we’re going to discuss the three main types of foundation cracks, how they should be repaired, and provide you with additional resources along the way.


Hairline Foundation Cracks

In case you’re not familiar with hairline cracks in concrete, let me explain.  A hairline crack is  very thin, no wider than a penny’s thickness. If you’re not sure? Hold a penny between your first finger and thumb, and place it next to the crack.  If the crack is too thin to hold the coin, or is just barely wide enough, it’s a hairline crack. The term “hairline” represents what a hair would look like if it was on your foundation.  If the crack in your foundation looks more like a hair than a gap or separation, it falls into the hairline crack category.   

Thin crack in a poured concrete wall.This photo was taken by an Acculevel project manager during a routine free estimate.  Damp drywall alerted the homeowner that there was an issue.


Foundation cracks don’t always let water seep into your home, and they should be repaired whether they do or not.  Any crack, once formed, will continue to grow.  Repairing cracks while they are still small is definitely the wisest thing to do; repairs at this stage are relatively inexpensive.  It is always cheaper to fix a small issue than a large one!  

There are a number of repair methods available for hairline cracks, but we recommend an epoxy fill.  Acculevel has tried a number of alternative methods, and our experiences taught us that epoxy is the most effective and longest lasting repair type


Multiple or Wider (Not Hairline) Cracks In Your Foundation

If the cracks in your foundation are wider than hairline, or if there are multiple cracks, this can indicate that your foundation is settling.   We have a detailed article about signs of settling if you want more specific information.

Additional signs to look for if you think the foundation is settling: 

  • Inside the house: check for cracks in the drywall.  Settling cracks will be in both the wall and ceiling. They are most commonly found around door frames and windows.  If you find any, test the nearest door or window.  
    • Does it open and close easily?  
    • Will it stay open without you holding it?  
    • Does it stay closed without being locked?  
    • If any of those answers are “no,” then this is more evidence of settling.
    • Please note: if you have drywall cracks and a gap between the baseboard and floor, that may be a sagging floor instead.  We have details about those symptoms in this blog.
  • Outside the house: watch for visible cracks in the foundation.  If your home has a block foundation (or a brick overlay), examine it for gaps or uneven spacing between those bricks/blocks. 


cracked brick exteriorThis photo was taken by an Acculevel project manager during a routine free estimate. The gaps and stair-step crack are signs of settling.


Large Cracks, Horizontal Cracks, and Stair-Step Cracks

If the cracks in your foundation are not settling cracks, but they are larger than hairline, you need to take action.  If the cracks in your foundation are long horizontal ones, are shaped like stairs, or the foundation wall is leaning inward, you need to take action quicklyThese are signs that the wall is under significant hydrostatic pressure and beginning to weaken.  

concrete block wall with multiple cracksThis photo was taken by an Acculevel project manager during a routine free estimate.  The cracks are forming between the blocks, creating a stair-step crack.


bowing block basement wallThis photo was taken by a different Acculevel project manager.  This is an example of a long horizontal crack, and the wall is bowing inward. 


For these types of cracks, the best repair method is carbon fiber straps

The straps are secured to the wall with an epoxy application.  This epoxy seals the wall and fuses the strap to it.  Properly secured, this bond is permanent and can hold up to a tremendous amount of force. 

The straps have specially designed anchors for use at the top and bottom of the wall.  The top anchor is attached to the rim joist; this is essentially the lowest layer of the main (or first) floor of the house.  This is done to stop the top of the wall from sliding inwards.  The bottom anchor attaches to the floor of the basement, which is essential to prevent any shearing (sliding) of the wall at the bottom.  

carbon fiber strap anchorsThese photos were taken by Acculevel crew members, after installing carbon fiber straps.  You can see the top bracket attached to the rim joist; the bottom bracket is attached to the lowest block in the wall (the floor was temporarily broken open to allow this).

Our Sales Director explains more about carbon fiber straps in this video:


What’s the Next Step?

I’ve included links throughout the article that will provide you with additional details about the causes of foundation cracks and how they can be repaired.  If you have additional questions, please check out our foundation repair guide.

link to foundation guide


This was designed specifically to be a resource for homeowners.  Please bookmark it and refer back to it any time you have questions about your home’s foundation.  

If you would like to have someone evaluate your foundation and estimate the repair costs, please seek out an experienced and reputable contractor in your area.  We encourage you to always use the Better Business Bureau for reference, to make sure the company you choose is insured and accredited by the BBB. 

Do you live in the Acculevel service area?  Contact us for an estimate, and we’ll schedule an appointment for you with one of our friendly and knowledgeable project managers


Kelly Kater

Over her twenty year career, Kelly has worked in a wide variety of fields: secondary education, nursing, biology, elder care, the postal service, multicultural development, and academia. She has developed a skill for translating industry-specific jargon into everyday language. Her goal is to share the knowledge and experience of the Acculevel team with homeowners, in a way that is both engaging and informative.

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