What condition can lead to foundation settlement due to soil moisture?

Foundation settlement can occur due to loss of moisture from the soil. When soil moisture decreases, especially in clay soils, the soil particles can contract and cause the ground to settle. This is commonly seen in areas with drought conditions or when vegetation that was retaining moisture is removed. The reduction in moisture content leads to a decrease in volume of the soil, which can result in voids and ultimately compromise the structural integrity of the foundation.

In contrast, gain of moisture can cause soil expansion, and stabilization usually refers to maintaining a consistent moisture level, thereby preventing significant shifts in the soil structure. Evaporation, while it describes the process of moisture leaving the soil, is a part of the loss of moisture dynamic but does not directly imply the condition necessary for settlement to occur. Thus, it's the loss of moisture that critically leads to foundation settlement issues.