There are several reasons why the Greater Houston Area includes large numbers of houses that show signs of damage due to foundation movement:
Houston’s Expansive Soils:
Expansive soils swell when they get wet and shrink when they become dry.
Houston climate is characterized by weather that alternates between very wet to very dry with occasional periods of little or not rain that may last as long as two years or more.
Flexible Slab-on-Ground Foundations:
The large majority of houses in the Greater Houston Area are founded on thin, flexible slab-on-ground foundations that are designed to distort as the supporting soils shrink and swell.
When you put the above facts together, it is surprising that there are not even more residential foundation problems than what we see.