The clay bowl effect is a term used to describe a situation where the soil around a building's foundation has a higher clay content than the surrounding soil, which can create a bowl-like shape that can collect and retain water. This can lead to increased hydrostatic pressure against the foundation and potentially cause damage over time.

Clay soils have a tendency to expand and contract with changes in moisture levels, which can cause the soil to shift and move around the foundation. If the soil around the foundation is significantly different from the surrounding soil, it can create a bowl-like shape that collects water and increases the likelihood of water infiltration and hydrostatic pressure against the foundation.

To prevent the clay bowl effect, it's important to properly prepare the site before construction, including assessing the soil conditions and preparing the foundation base to ensure proper drainage. It may also be necessary to install drainage systems around the foundation, such as French drains, to help divert water away from the foundation and prevent water buildup.

Regular maintenance of the drainage system and foundation is also important to ensure that water is not collecting around the foundation and causing damage. This may include regular inspections and repairs of any cracks or damage to the foundation, as well as ensuring that gutters and downspouts are properly installed and functioning to direct water away from the foundation.