All Structural Problems are caused by water. Get rid of the water, get rid of the problem.
Unreinforced concrete or masonry foundation walls have tremendous strength vertically but very limited resistance to lateral pressure. Most residential foundation wall are designed empirically - thickness of the wall versus the height of dry backfill.
If the adjacent soil becomes saturated, the lateral pressure against the foundation wall is increased by 15% sometimes, enough to nudge it inward and creating a crack.
If the water remains in the soil during a cold winter, frost will take hold and expand with 10 times the allowable pressure causing cracks for sure.
Four reasons the soil around the home becomes saturated.
- A clogged perimeter foundation drainage tile.
- The grading is level or slopes back toward the house
- Rain water leaders are not extended out from foundation
- Broken underground sprinkler systems or water mains
If the home is nearby a creek or storm ditches, occasionally overland flooding can quickly saturate the soils around the home to causing structural problems.