Page 38 - Construction Waterproofing Handbook

2.2 CHAPTER TWO
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 com-
pleted by one or a combination of steps. Soil adjacent to a building should be graded
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and sloped away from the structure. Slopes should be a minimum of 2 in/ft for natur-
al 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.

GROUNDWATER CONTROL

Besides protection from normal groundwater levels, allowance is made for temporary
rises in groundwater levels to protect interior areas. Groundwater levels rise due to rain

FIGURE 2.1 Below-grade drainage detailing.