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.|