Concrete Foundation Repair Explained

Ordinarily, concrete foundation repair is not necessary. Most concrete is a very long lasting material. In fact, some concrete foundations built more than a hundred years ago in Colorado's gold country villages still stand today. But not all concrete foundations are as sturdy and lasting as these. Some deteriorate with weather with time and wear. When they do, they often need to be repaired. If you find yourself needing to repair a concrete foundation here are 5 steps that will help you complete your project.

Things You'll Need:

• Circular power saw
• Masonry blade
• Steel rebar
• Shrink-resistant repair mortar
• Crack chaser blade
• Steel trowel
• Water hose
• Epoxy gel adhesive
• Putty knife
• Epoxy resin
• Concrete grinder
• Leveling compound
• Concrete sealant

Step 1 – Remove Damaged Portions

Use a circular saw with a masonry blade to cut out and remove the damaged part of your concrete foundation. If you find steel rebar in the foundation, leave it in place and remove rust, concrete debris and any dirt you find stuck to it. Replace any damaged rebar with new, clean bars. In removing the damaged section of concrete, cut out a square of the damaged concrete, with the damaged portion located in the center of the square. Be sure that in cutting the concrete into a square, you make the edges 90 degrees, leaving ¾" to 1" margins between the edge of the square and the damaged concrete.  

Step 2 – Fill Cut-Out Areas

Use your repair mortar to fill areas where you have removed damaged or deteriorated concrete, then use a steel cement trowel to level the new mortar.

Step 3 – Route Cracks

Replace the masonry blade in your circular saw with a crack chaser blade, then route open cracks so they are 3/4" to 1" deep. The surface of the new crack sides should be vertical when you've finished routing. Use water to flush debris and dirt from the crack, then allow the crack to dry enough that there is no moisture left in the crack. Be sure all moisture has evaporated. Remaining moisture can prevent epoxies you later add from adhering to the concrete surfaces.

Step 4 – Apply Epoxies

With a putty knife, apply your epoxy gel adhesive to the surfaces of larger cracks. When the adhesive has dried, inject epoxy resin until the crack is completely filled.

Step 5 – Level the Surface

When the mortar and resin have cured, use a concrete grinder to grind and level the foundation's surface, leaving it slightly rough. When finished leveling, wash the entire surface with warm water, so that all dirt and debris are washed away. Using a mixture of leveling compound, pour it onto the foundation until you've covered the entire surface with ½" of compound. Trowel the surface level, allow it to dry, then grind it until it has a smooth surface.

To repair other damaged areas of the foundation, follow the same procedure as above, waiting until all epoxies and mortar have completely set before making further cuts in the foundation.