Hydrostatic Foundation Problems

Hydrostatic Pressure

• "Hydrostatic pressure" is a term that refers to the amount of weight and force that water is exerting on the walls and floor of your house. The foundation of your home must resist pressure from the soil and rock underneath and the pressure of water. Hydrostatic pressure also regards the water absorbed in the soil, which adds weight to the foundation. Just as serious is the question of the water table itself. The higher the natural underground water rises, the more pressure will be placed on your house. The water table can be increased through poor surface drainage and heavy rains, adding more pressure.

General Problems

• No matter how well built the foundation, if water pressure rises around the house, your basement can turn into a flood area. Concrete is porous and can — and does — leak. The greater the pressure of the water, the greater the chances and severity of the resultant leaks. If untreated, basement leakage will lead to basement flooding. Equipment like water heaters and electrical systems can be destroyed. Mold and mildew can build up, causing an unhealthy environment. Hydrostatic pressure can also cause humidity — water vapor — to be forced through the pores of the concrete, leading to a much higher level of house humidity. Water bugs can also take up residence in the pools of water within and without the house.

Block Problems

• Concrete blocks and clay foundations are the worst for hydrostasis. Blocks have the porous nature of concrete, but since they do not form a single wall, there are cracks where mortar fills the space between the blocks. These cracks are the areas where water pressure will cause leaks. Clay foundations are even worse, since they are a honeycomb of air pockets, which can easily lead to leakage and increased humidity, especially under high pressure. Over time, the entire integrity of the basement can be damaged, sometimes irreparably.

Concrete Problems

• If you have a monolithic basement design, then dealing with drainage is more difficult. In a monolithic design, basement concrete is poured so that the walls and floor are a single, solid unit. To address drainage issues, you would need to drill into the floor to install a drain or pump, which would harm the integrity of the unit. However, a separate floor -- a nonmonolithic system -- is also a problem because the water table will exert hydrostatic pressure upward, leading to a lifted floor that springs leaks from all the cracks in the wall. Repairing this problem can be very expensive and inconvenient. Making matters worse is the decade-long process of drying and curing poured basement. Curing and drying often leads to shrinkage, which creates cracks that water can exploit. The reality is that the water pressure will always win — eventually — against the basement.