1807.1.3 Ground-water control. 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 1807.2.

1807.1.3 Ground-water control. 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 1807.2. The design of the system to lower the ground-water table shall be based on accepted principles of engineering that 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 operate and the rated capacity of the disposal area of the system.

Code Interpretation

This section implies that dampproofing is required if the water table is maintained a minimum of six (6) inches below the bottom of the structure. If the water table is maintained within six (6) inches of the bottom of the structure or if hydrostatic pressure exists, than waterproofing is required.

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

The section also implies that the ground-water table must be lowered by implementing a drainage system that is designed to meet the following engineering principles:

1. Permeability of the soil

2. Rate at which water enters the drainage system

3. Rated capacity of the pumps

4. Head against which pumps are to operate

5. Rate capacity of the designed area of the system