How to Stabilize Stone Foundations

Inject a mixture of sand, water and cement under the stones to shore up the foundation and fill in cracks that can lead to further destabilization. Use a pressure grouter to insert the mixture under and into the stones. According to the "Home Rehab Handbook," although the grouting stabilization technique is inexpensive, it can be difficult to control where the grout settles and how much of the cracks it fills.

Insert a heavy-duty truck jack under a corner or side of the house if the foundation settling is localized in one area. Set the jack under the edge of the foundation and raise it until you can reach in to excavate the spot and work safely in the area.

Clear out a 3- to 6-foot spot where the foundation is beginning to sag. Remove loose dirt and stones with a rake and shovel.

Insert steel rods with steel plates attached to each end between the stone and the ground as reinforcements. Pour cement around the newly inserted rods and allow cement to dry before lowering and removing the jack. After removing the jack from the edge of the foundation, add another steel reinforcement on the end of the building. Fill with cement or grout, following package instructions.

Combine both techniques for a more secure foundation. Lift the foundation with a jack when the grout between the stones is stable enough to withstand the pressure. Fill in the cracks with grout and let it dry before inserting steel rods. Fill the rest of the cavity with cement before removing the jack.