The soils around your foundation experience wetting and softening primarily for these three reasons:
Heavy Rain & Flood Conditions: As clay soil gets wet, it holds on to water and becomes very soft. This soft soil can be weak, causing the home to shift (or “sink”) down into it.
Poor Drainage: If water is allowed to stand or “pond” next to your home, the soil will absorb the water. As it does, the soil can weaken and soften once again.
Plumbing Leaks & Broken Water Lines: When a home’s plumbing begins to leak under a slab foundation, the soils underneath can begin to become saturated, weakening their supporting capacity.