A homes foundation is in direct contact with the ground and the buildings structure sites on the underlying zone of soil or rock. The foundations function is to transfer the structures load to the underlying soil or rock, without excessive settlement or movement.
Movement of the soil beneath a home can severely damage the foundation. That’s why the soil beneath your home is often referred to as your second foundation.
Slab-on-Grade foundations are shallow foundations that are usually constructed of reinforced concrete. Slab-on-Grade Foundations can be built quickly and are relatively inexpensive to build. The function of a Slab-on-Grade Foundation is not to resist or limit the amount of heave that might occur beneath a slab foundation, but to fluctuate with the shrink and heave. Slab-on-Grade houses do not have basements.
Shallow Foundations are susceptible to season movement from rainfall, drought, freeze/thaw cycles, temperature changes and transpiration of moisture thru the roots of large plants and trees.