Basement and crawl space water problems are almost always caused by water pressure, or hydrostatic pressure, against the walls, foundation, or floor of the basement or crawl space. According to the experts, hydrostatic pressure can result from a number of different sources, including poor grading, defective gutters and downspouts, a high “false” water table, or the failure of a foundation’s footing drain. The solutions to these issues vary depending on where the problem lies, though persistent water problems are often solved only by relieving the water pressure itself.
Poor grading. With proper grading, land slopes away from a house. In some cases, however, the lot site may have been poorly graded when the home was built, or soil erosion may have changed the lie of the terrain. Over time, the slope of the grading can also shift as loose dirt settles. When groundwater runs toward the home rather than draining away, the result is often foundation seepage.
Defective gutters and downspouts. Gutters and downspouts are designed to carry water away from the house and its foundation. Gutters that leak or overflow and downspouts that release water too close to the home can often be the culprits in water problems that spring up suddenly.
High “false” water table. The water table is the depth at which water saturates the soil. The natural water table is usually far below the home; however, a home’s foundation is built into excavated ground, which then gets refilled with loose soil. Water readily collects in this soil, creating a “false” water table that can rise higher than the foundation. The false water table surrounding the house fluctuates with the weather and season. Excessive amounts of rain, more runoff than usual from water sources at higher levels, and water that improperly drains away from the home can also cause this false water table to rise, causing seepage.
Footing drain failure. Drainage systems can fail over time as silt settles into them and creates clogs. This can happen to any footing drain system installed around a foundation whether the system is made of old clay tile, pipe and gravel, or a strip drain. Footing drain failure leads to the buildup of hydrostatic pressure and then to leaks.
Interior drainage system. The installation of an interior drainage system requires opening and removing part of the slab around the interior perimeter of the basement floor, installing the drains, and then replacing the removed sections of the floor. Many interior drainage systems also involve the installation of a sump pump. The process can create dust and debris, so the work area must be sealed off from the living area before work can begin.
If your home’s interior drainage system involves a sump pump, be sure that the sump pump is maintained on an annual basis. Sump pumps do not work without a power source, so if your area typically loses power during storms or experiences frequent power outages, ask your waterproofing contractor about a battery-backup sump pump.
Exterior drainage system. By installing a wall and footing drainage system around the below-grade exterior foundation walls of a structure, hydrostatic pressure against the basement or crawl space walls is alleviated, and the water is routed away from the structure. Prior to installing this type of drainage system, a waterproofing sealant should be applied to the exterior of the foundation walls to prevent seepage as water flows down toward the drain.
Injection method. The injection method is used to seal cracks in the foundations of homes. The crack is located, small holes are drilled into the crack, and an epoxy or polyurethane material is injected. These materials expand, which limits water from entering the home. Once the entire crack is full of epoxy or polyurethane, the repair is complete. The injection method is not suitable for fixing all types of water-related problems; therefore, homeowners should consult with professionals before determining if the injection method is the best option for their needs.
Gutters and grading. If part of your home’s water problem is caused by negative grading or inadequate or missing gutters and downspouts, these issues should be fixed even if more invasive measures are also necessary. If your gutters consistently overflow during rainstorms, dumping gallons of water directly on your home’s foundation, the gutters may be clogged or too narrow, or they may have been installed with an inadequate degree of slope. Likewise, ground that slopes toward your home’s foundation should be regraded so that water will flow away from the house.
Foundation cracks. The most common entry points of water into a house are the cold joints between the basement wall and floor and the footing, but shrinkage cracks and pipe penetrations in the walls and floor may also allow entry. Porous cement block walls and mortar joints are especially susceptible to leakage. These cracks should be fixed to prevent ongoing problems.
For many years, the widely accepted opinion was that ventilating a crawl space was the best way to control moisture, mold, and mildew. Thus, crawl space ventilation was written into many building codes, and builders duly installed vents to comply. The US Department of Energy later funded a crawl space performance study that found that a sealed and conditioned crawl space has many advantages over a vented crawl space, including lower energy consumption, lower moisture content in the home’s wood, lower humidity, and reduced fungus growth.
In order to properly seal a crawl space, the study recommends a number of procedures, including installing a standard waterproofing system; sealing all exterior wall penetrations and vents; installing a thick, plastic vapor retarder or barrier on the walls and floors; sealing all penetrations of ducts, electrical wires, and plumbing through the subfloor; insulating the spaces between floor joists; and installing a humidity-management system.
Waterproofing is a cyclical business, and when especially wet conditions occur, the best waterproofing companies can get backed up. Unfortunately, unsuspecting homeowners may take a chance with any company that can start right away. Other homeowners make the mistake of not maintaining their waterproofing system, which, like all household systems, can degrade over time. A waterproofing system that has not been checked regularly may fail. Good waterproofing companies will know how to maintain their products, ensuring you get the best performance from your investment