Foundation Crack from Lateral Movement and Hydrostatic Pressure
Foundation cracks may develop when there is moisture saturated soil pushing on the exterior face of the foundation wall. The hydrostatic pressure forces the wall to bend inward creating a crack and opening in the foundation wall. This crack is usually horizontal, open more than hairline, and shows signs of water intrusion.
Hydrostatic pressure refers to the pressures caused by water pushing against slabs and foundations, particularly underground concrete block or poured concrete walls of foundation and crawlspaces.