Problems that result from moisture intrusion can be extensive and expensive to remedy. And, it is a major cause of lawsuits against homeowner associations, real estate management companies, architects and developers. Research has shown that many people develop health problems from exposure to mold and mildew spores that result from moisture intrusion. From our experience, the intrusion can result from diverse sources. At the other extreme, if groundwater is present above a basement floor, the water can intrude into a structure through shrinkage cracks in poorly constructed concrete members, hairline cracks, and improperly sealed joints.
Moisture can also intrude downward through a concrete roof structure.
Water vapor, leakage, and capillary action result in moisture intrusion into structures. Water vapor moves from one area to another whenever there is a difference in vapor pressure between two areas. If the groundwater table is above a basement floor, then the floor and walls of the basement are subject to hydrostatic pressure, and considerable amount of water can leak or flow through the wall cracks or joints. In Southern California, concrete flat slabs are commonly used in basements or subterranean garages. Pedestrian walkways, planter areas, and lightweight structures are commonly built on top of these concrete flat slabs.