Various factors can influence the differential movement of slab foundations. The mechanism of the typical causes for slab distress is best summarized as follows:
- The maintenance of the foundations perimeter moisture.
- The amount of water/moisture in the soil prior to placement of the concrete.
- The grading of the perimeter soils up to 10 feet away from the foundation.
- The presence of shallow groundwater seepage (bog).
- The past or present influence of large vegetation and/or trees.
- The presence of fill soils and the various amount of cut and fill across the lot.
- Soil creep.
- Structural design of the slab for the assumed soil conditions.
- The construction execution in the field.
- The antecedent weather conditions prior to pouring the concrete.
- Extreme weather patterns causing soil consolidation.
years of observation and research the most significant
soil-structure interaction mechanism causally related to
differential slab movement is due to soil moisture withdrawn from nearby root systems of trees extracting moisture from
the soils beneath the foundation.