Reasons for Foundation damage
Foundation settlement and movement can be caused by building on expansive clay, compressible or improperly compacted fill soils, or improper maintenance around foundations.
Whatever the cause, settlement can decrease the value of structures and even render them unsafe.
In any case, water is the basic factor in the vast majority of expansive soil problems. Certain components of different soils tend to swell or shrink with variations in moisture. The extent of this movement varies from soil to soil.
Those soils highest in clay content are generally more susceptible while those lowest in clay content are the least affected. In some areas the movement in insignificant; in others, it is quite pronounced.
When unstable soils are used as a base for a foundation, the tendency for movement is present for the foundation as well. Since soil movement is rarely uniform, the foundation is often put in imbalance. The problem shows up in slab, pier and beam type foundations.
If all the soil beneath a foundation or slab swells at the same rate, there usually is no problem. Problems occur, however, when only a part of the slab settles. Then, the differential movement can cause cracks or other damages.
In residential properties, slab settlement problems can result in potential damage to the structure, potential accidents, and loss of real estate value. Poor drainage, tripping hazards, rough floors, unsightly cracks, and equipment malfunctions may also result from concrete slab settlement.