Concrete Block Foundation: How to Repair Cracks

a crack in concrete wall
What You'll Need
Concrete Caulk
Concrete Patching Materials
Wire Brush
Water Hose with a High Pressure Nozzle
Concrete Sealant

Cracking is perhaps the number one reason for concrete block foundation repair. Cracks in any type of concrete foundation are concerning, but in a concrete block foundation, they need to be addressed as quickly as possible to avoid additional damage and repair costs to the foundation and the home that rests on it.

There are any number of causes for a concrete block foundation to crack: water, shifting in the ground, tree roots deteriorating. Regardless of the cause, if they are caught early, it is easy to repair these eye sores quickly and effectively using these steps.

Step 1 — Prepare the Surface

First, you will want to prepare the surface of the area that you will be patching. Scrub the concrete with a wire brush to remove any loosened material. Use strokes in all different directions to ensure that you get any material that is crumbling off. Spray the area with a high pressure nozzle on the hose. It doesn't need to be a power wash job (in fact this may cause more damage); just a garden hose will do. Let the surface and area dry completely before attempting to patch it.

Step 2 — Fix Smaller Cracks

Use the concrete caulk and work the substance into the cracks as much as you possibly can. Fill any cracks or holes completely. Let the caulk cure for the designated amount of time on the container before attempting any additional work.

Step 3 — Fix Larger Cracks

Larger cracks can be filled with the concrete patching materials. This can be found in most local hardware or home improvement stores. These materials are limestone-based and should be wet when applied. Again, read the package directions to mix the material to the proper consistency and moisture content. Fill larger cracks with this mixture, and allow to cure completely. Because concrete patching materials are limestone based, they will expand as they dry, filling the crack as completely as possible.

Step 4 — Seal the Repairs

Use a concrete sealant to seal up any cracks or repairs. Make sure that before you apply any sealant, that all caulk or patching materials are allowed to cure and dry completely before applying. The sealer will help to prevent moisture from entering at the same place (which is the most frequent culprit in the first place), undoing the repairs and creating even more problems. Most caulk and patching materials are able to be painted, so if your foundation is painted, once the caulk has cured you can touch up the paint over it.

The foundation is the skeleton of your home, and critical to it's structural integrity. If the problem is large, or the walls of your home are cracking or floors are tilting, you need to call in a professional to assess the damage to the foundation and determine the proper course for repair.

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