GROUNDWATER CONTROL: protect interior areas.

Water present at below-grade surfaces is available from two sources—surface water and groundwater. Beyond selection and installation of proper waterproofing materials, all waterproof installations must include methods for control and drainage of both surface and groundwater.

Surface water from sources including rain, sprinklers, and melting snow should be directed immediately away from a structure. This prevents percolation of water directly adjacent to perimeter walls or water migration into a structure. Directing water is completed by one or a combination of steps. Soil adjacent to a building should be graded and sloped away from the structure. Slopes should be a minimum of  1 2 in/ft for natural areas, paved areas, and sidewalks sloped positively to drain water away from the building.

Automatic sprinklers directed against building walls can saturate above-grade walls causing leakage into below-grade areas. Downspouts or roof drains, as well as trench drains installed to direct large amounts of water into drains, direct water away from a building. Recommended controls for proper water control are summarized in Fig. 2.1.

FIGURE 2.1 Below-grade drainage detailing.