Concrete or block foundations occasionally deteriorate and fail. As the component that holds the house up, foundations with problems need to be repaired. Obviously the type of damage will determine how the repairs will be made. Quite often repairs will involve removal of dirt from the exterior of the foundation walls or replacing cement or blocks within the foundation wall.

Repairing a Damaged Foundation

Any crack in a foundation should be investigated. This may involve monitoring the crack for a period of time to determine if it is growing or moving. A small crack that is stable for several years may only require a cosmetic patch. Cracks that grow and move will require a more thorough investigation. It is more important to learn what is causing the crack to grow and move and solve that problem. After the situation is stabilized the crack can be patched. Take photographs and measurements. Compare them to new photographs and measurements taken a year later. You can make repairs to foundation cracks with masonry epoxy or other cement product. Remove all loose cement from the edges of the crack before filling. Seal cracks that leak water with silicone caulk or polyurethane foam sealant. Foundations that are moving may require stabilization. This is often done with mud jacking or grout pumping. These tasks are undertaken by professionals with the proper equipment for forcing a watery cement into the ground to create a more stable area for the foundation. Foundations that are bulging in from exterior pressure pose another problem. Steel I-beams are placed on the inside of the basement wall and attached to the foundation and floor of the house above. The space between the beams and the wall is filled in, forcing the foundation wall back into place. Straightening the foundation walls should also be accompanied with steps to remove water from the soil pressing on the exterior of the foundation. Drain tiles can be installed to reduce the pressure on the foundation. Because of the importance of the integrity of the foundation, any problems should be at least assessed by a construction professional. In some cases the work can be done by the homeowner. This is particularly true when it comes to repairing stable cracks. In other cases, such as a bulging foundation wall or shifting foundation, the work will require skills and equipment available only from a professional contractor.

Source:

Inspectapedia: "How to Repair Damaged Foundations"

Foundation Repair Association