The most important topic on this site
The way we (the authors) make an engineering assessment of a slab-on-ground foundation based on the same understanding or model that the modern slab design procedure is based on. To the best of our knowledge, our procedure is more tightly related to the standard design procedure than that used by any other engineer currently practicing in Southeast Texas.
Five main ideas you need to understand
How clay soils react to changes in moisture content.
How the soil moisture content reacts to the placement of a slab-on-ground foundation.
How the soil supporting a slab-on-ground foundation reacts to changes in moisture content.
How a slab-on-ground foundation reacts to changes in the supporting soil.
How a wood framed house reacts to a distorted slab-on-ground foundation.
Understanding each of these topics will help you immensely in reading and understanding engineering foundation reports by us and others.