How to Repair Cracks in Cinder Block Foundation Walls (Simple, Fast Solution for Minor Cracks)

Written by Andrew Thron in Uncategorized Last Updated April 25, 2024
How to repair cracks in cinder block foundation wall

Seeing cracks in your home’s cinder block foundation walls can be alarming. Further, if these cracks are left un-repaired, they can worsen over time. Although some types of cinder block foundation cracks can compromise the structural integrity of your home (for example, long horizontal cracks), other cracks are harmless and only serve as an eyesore (for example, small vertical cracks).

Major cracks typically require an analysis by a structural engineer and the repairs can be quite costly. If you suspect that the cracks on your cinder block foundation are major, it is highly recommended that you consult with a foundation repair specialist and a structural engineer.

For minor, cosmetic cracks, however, the repairs can be quite simple and fast. In fact, the average homeowner can tackle small cosmetic cracks in a cinder block wall in just a few minutes.

What Causes cracks in foundation walls?

Minor Foundation Cracks are normal and are typically a result of your home settling over time. A minor crack is anything cosmetic (e.g. hairline cracks) that does not pose a structural compromise to your home.

Large horizontal cracks in the foundation can be caused by many factors such as:

  • Poorly constructed foundation walls that failed over time
  • Hydrostatic pressure “pushing in” on the homes foundation
  • Earthquakes or substantial differential settlement of the soil beneath and around the home’s foundation.

Large horizontal cracks are generally serious and typically require a professional repair based on a structural engineering report.

This is an example of a serious, horizontal foundation wall crack that requires a professional repair
This is an example of a serious, horizontal foundation wall crack that requires a professional repair

One of the most common repairs for large, horizontal foundation cracks is the installation of carbon fiber straps. Carbon fiber repairs are costly ($1,500-$7,000) but are very effective for reinforcing the home’s foundation to prevent further damage.

Example of the same horizontal crack after it was repaired with carbon fiber straps
Example of the same horizontal crack after it was repaired with carbon fiber straps

If you find yourself with a non-structural, cosmetic crack, you can repair it VERY easily by following the steps below: 

Identify the Cracks in the Cinder Block Foundation Walls and Confirm that they are Minor

The first step in repairing cinder block foundation cracks is to identify all of the cracks and confirm that they are vertical, minor, and cosmetic.

Example of a small, cosmetic cinder block foundation wall crack
This is an example of a small cosmetic cinder block foundation wall crack

If your foundation cracks look similar to the photo above, you can move on to the next step.

Prepare the Surface of the Cinderblock Wall for the Repair

Before you can repair the crack, you will need to clean out the crack – removing any dirt or debris. Additionally, use a chisel and hammer to chip away any loose cinder block.

To prepare the surface, use a chisel or a screw driver to remove dirt and debris in and around the crack and to “rough” up the surface of the crack
To prepare the surface, use a chisel or a screw driver to remove dirt and debris in and around the crack and to “rough” up the surface of the crack

Prepare the Hydraulic Cement so That it Can be Applied to the Crack

To repair the cracks in the cinder block foundation, we will be using hydraulic cement. Hydraulic Cement is the best for this application since hydraulic cement, by nature, is crack/shrink resistant and waterproof. 

This is the Hydraulic Cement that was used to repair the cracks in my foundation
This is the Hydraulic Cement that was used to repair the cracks in my foundation

Add water to the hydraulic cement mix in accordance with the manufacturer’s recommendations and then you can begin to apply the mix to the crack.

Mix up the hydraulic cement and apply it to the foundation crack
Mix up the hydraulic cement and apply it to the foundation crack

Repair the Cinder Block Foundation Wall Crack by Applying Hydraulic Cement.

Continue to apply hydraulic cement to the cinder block foundation crack using a concrete trowel. Fill the entire crack with hydraulic cement and “feather” out the edge so that it is flush with the surrounding cinder block wall.

Once your hydraulic cement is mixed up according to the manufacturer’s recommendations, apply the cement to the crack using  concrete trowe
Once your hydraulic cement is mixed up according to the manufacturer’s recommendations, apply the cement to the crack using  concrete trowe
Be sure to force the cement into the crack to ensure that the void is sufficiently sealed. “Feather” out the cement so that there are no elevated surfaces and to ensure that you have a nice even finish. 

Allow the Hydraulic Cement to Dry and then Paint the Repair to Match the Surrounding Cinder Block Wall

After repairing the crack with hydraulic cement and allowing it to dry, simply paint the repair so that it matches the rest of the cinder block foundation. I used a paint sprayer to paint my crack repair, but a paint brush or roller will also work well.

Once you have given the cement adequate time to dry and harden (according to the manufacturer’s recommendations), paint the newly applied cement to match the surrounding foundation color.
Once you have given the cement adequate time to dry and harden (according to the manufacturer’s recommendations), paint the newly applied cement to match the surrounding foundation color.

For a step-by-step video guide showing every step in the cinder block foundation wall repair process, you can watch my YouTube video below which has already helped over 100,000 people complete a similar repair.

With the crack repaired and the foundation painted, you have successfully repaired your cosmetic foundation crack. Again, please consult a professional/structural engineer about any foundation cracks.

Thanks so much for checking out ATImprovements! If you learned something from this project, you might also like these other DIY Projects:

Andrew Thron

Andrew Thron has established himself as an expert in the field of home renovation helping millions with their DIY home renovation and home improvement projects through detailed YouTube video tutorials, Instagram project ideas, and step-by-step blog articles.

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