This type of soil generally contains clay minerals which expand and contract depending on their moisture content. Exterior and interior cracks are normal conditions for homes located in active soil areas. Changes in soil moisture content may cause the foundation to uplift during wet periods and deflect downward during dry periods. Foundations built over such soils are expected to undergo these movements without affecting the structural adequacy or the load-carrying capacities of the foundation , floor slab, or structural members. These movements may result in cosmetic deficiencies in the superstructure supported by the foundation and related parts, but does not in itself indicate a structural defect.
Properties built in active soil areas require special precautions.
Improper homeowner maintenance can adversely affect the performance and structural integrity of a foundation constructed on active soils. We recommend to maintain uniform moisture content in the soil near the foundation. This can be accomplished by good site drainage designed to avoid standing water near the foundation. Perimeter roof guttering that discharges the water well away from the foundation and encourages the water to run off site is best. Underground guttering discharge is a good design if the site does not have a sufficient slope.