Stone foundations are not much used nowadays, but in certain old-style houses, they are still existent. Stone foundations are usually difficult to repair and require professionals to handle it.

Stone cracks in foundation could be due to a number of reasons. As in most cracks, the prime cause is of leakage of water. If it is a mortared stone wall, then a leakage crack can be identified as a single thin crack localized around a particular region of the wall, especially where the stones join together. Trees that spring their heavy underground roots through the soil may also cause mechanical weathering of stone foundations. Stone also crumbles under vibrations which may be caused due to vehicles running aboveground.

To repair minor cracks in mortared stone walls, first a little of the mortar is chiseled out (about inch) around the crack. Fresh mortar is mixed in a bucket. The proportion is one part cement, one part lime and six parts of builders sand. This mixture is mixed with the correct proportion of water so as just to allow the components to stick together. The thicker the mortar, the better it will stick to the groove. Readymade mortar is also available in hardware stores. Then with the help of a pointing trowel, the wet mortar is embedded in the crack. It is not easy to keep the mortar in the crack and it is a repeated process. Once the mortar is dried, the crack is repaired.

Stone foundations are very vulnerable to leakage problems. If the construction was shoddy, then there remain gaps between the stones where the mortar was filled, which become an entry point for leaking water. If the problem is large enough, then contractors excavate a bit of ground around the foundation and create provision for the water to run off, repairing the faulty part with mortar. This is called as external excavation.

In another process, the affected floor tiles are removed and a drain tile is fitted. So that the problem of water seepage does not recur, appropriate drainage suction pumps such as a sump pump or floor drain is installed. The floor is then replaced. This is called as the internal breakout technique.