Expansive soils create foundation damage. Expansive soils, including, clay soil, shrink-swell, and heavable soil, are all different names for the same thing. Expansive soils are responsible for more damage to buildings than any other natural hazard.
This type of soil contains minerals like smectite clays, which absorb a lot of moisture. As the expansive soil soaks up water it expands – up to 15 times its dry volume. Furthermore, the expanded soil then pushes against your foundation and creates cracks or waterproofing problems.
In fact, as the expansive soil dries, it shrinks. The soil shrinkage gives your foundation room to move around. Consequently, this extra room removes the support from your foundation and will cause cracks, settling, and other foundation damage. The pressure of expansive soils against your foundation can exceed 30,000 pounds per square foot.