Expansive soils will swell when wet and contract when dry and this active movement causes the foundation to shift.

Caused by slow downward movement of expansive soils under the influence of gravity and the effect of moisture changes.

Where soils are not adequately compacted, they can compress under a foundation load.

Process by which clay soils slowly decrease in volume under long term static loads (i.e. the weight of the house.

Too much water can reduce the bearing capacity and is caused by poor surface drainage, leaks in water lines or plumbing or a raised groundwater table.

Sometimes footers are either non-existant, designed too small for the current loads or not build to the design at the time and hence have inadequate bearing capacity.

Vibration from seismic activity during major earthquakes.

Hillside locations, poor surface drainage, leaks or other underground water movements.

Root systems can expand and can draw moisture from the soil beneath the foundation causing settlement and large roots can push up foundations.