Where the ground water table is lowered and maintained at an elevation not less than 6 inches (152 mm) below the bottom of the lowest floor, the floor and walls shall be dampproofed in accordance with Section 1813.3. The design of the system to lower the ground water table shall be based upon accepted principles

of engineering which shall consider, but not necessarily be limited to: permeability of the soil; rate at which water enters the drainage system; rated capacity of pumps; head against which pumps are to pump; and the rated capacity of the disposal of the system.

The code implies that dampproofing is required if the water table is maintained a minimum of 6 inches below the bottom of the structure. If the water table is maintained within 6 inches of the bottom of the structure or if hydrostatic pressure exists, then waterproofing is required.

It is the designer’s responsibility to review the site engineering analysis for water table conditions and soil analysis to determine if dampproofing or waterproofing is required and what type of application is best suited for the project.