How to Repair a Concrete Block Wall

Wall built from concrete blocks.

A concrete block wall, whether outdoors or otherwise, can suffer damage due to weather, flooding, or accident. Readily available materials can fix some cracking in a block wall without having to tear it down and add new concrete. Follow the instructions below and take care of this damage before it can cause problems

Clean and Prepare the Concrete Blocks

Man cleans a damaged concrete wall for crack and hole repair

Check all areas that will need repair including cracks and holes. Then, use a metal file to smooth off any rough mortar bits around the damage. Wear work gloves during this process to protect yourself from some nasty scrapes. Once you're finished, clean off the concrete with a hose to get rid of any dust left over. While the wall dries, bring the rest of your materials up to the repair site.

Mix and Apply Concrete

Man uses concrete mix to repair concrete block wall

Prepare the ready-mix concrete blend as per the instructions on the product. Work quickly so it stays flexible until the job is finished. Load the pointed trowel with concrete and slough off excess on the carrying board. Fill the mortar gap between blocks with it, holding the trowel at an angle and wedging the material in. Smooth over it with the point and edge of the trowel.

Use Caulking to Fix Repairs that Need Adhesive

Man using general-purpose caulking on concrete block wall

Slide the tube of general-purpose caulking into a tubular caulking gun. Trim off the tip to as wide as your little finger to let the caulk flow out. Then, put the tip of the gun near the repair spot and squeeze until the sealant comes out. Completely fill the area with adhesive and smooth with a damp cloth.

Use Mortar and Concrete Caulk to Fill Holes

Man uses mix of mortar and concrete caulk to fill a hole in block wall

If your wall has holes as well as cracks, you'll need to use a slightly different material. Put a tube of combined mortar and concrete caulk into the caulking gun. Open it by cutting off the tip and squeezing until the contents come out in a bead. Fill the hole, working upward from the bottom. Apply in overlapping layers from side to side, using a generous amount. Clean off the trowel and use it to smooth the edges when complete.

Repair with Concrete Epoxy for Leaks

Man using concrete epoxy to finish wall repair

To repair a leaking concrete block wall in a basement, you'll need concrete epoxy cement to make a waterproof seal. Concrete epoxy cement expands it dries to make a seal that can withstand a waterspout of several hundred pounds of pressure.

After you've smoothed the edges of the crack with the file, trim them into a dovetail shape like the support of a drawer either with the metal file or a wedge. Put the concrete epoxy cement on the caulking gun, open up the tip to draw out a small amount, and squeeze it smoothly into the crack. Smooth over the repair with a damp cloth and allow it to set.

Concrete block wall repairs are within the skills of do-it-yourself people. Have the confidence to try, and you will be successful.