A house foundation depends on the uppermost soil layers. These layers are stabilizing the whole foundation and provide the supports for the structure. If the soil is not one that can bear the weight or wasn’t properly compacted during grading phase of the job site, the foundation is prone to settlement as the soil that supports it consolidates.
Another concern is the various soil conditions. The house may settle differentially because of different conditions in different soils that support the house foundation. In this case, the foundation system should be designed specifically for the various soil condition in the foundation site.