Additional problems such as hydrostatic pressure against foundation walls or surface water mixing with expansive soils next to or under a foundation can lead to cracking of the slab and foundation walls. Soil in this case does not refer to the topsoil but the layer of soil that is impervious to water such as clay, which directs the water away from the house. If non-porous soil next to the foundation slopes toward the house, water will begin to accumulate. The overall lo t grading is also an important concern since surface water may enter from adjacent properties. Generally, if the house is located on a slope or on a lot that receives water run-off, swales are often used to direct the water around the house.
Swales are shallow ditches or depressions in the landscape that capture the water run-off.
Then, like a small creek, the water is directed around and away from the ho use.