The most common cause of foundation failure is changes in moisture and the density of the soil.
For example, when residential subdivisions are developed, especially in wooded areas, the top soil layer is quite thick. This soil layer contains decomposing matter and root systems which will continue to decompose and compact for years after the subdivision is developed. It would not be practical or cost effective for contractors and developers to remove 2 to 4 feet of topsoil before developing the many acres it takes to build subdivisions. Also these soils often are very moist. So here is what generally causes foundation problems. The developers remove vegetation off the top of the soil. They bring in hard clay and river silt and build the soil up making it very hard on the top. Then they put in excellent drainage to prevent flooding. Now when it rains the water drains off the hard top soil. The water does not penetrate deep into the subsoil layer. This causes the subsoil layer to shrink. We also have decomposing top soil and root matter beneath the land fill layer. Thus most homes in subdivisions in Louisiana will eventually need foundation repair.