Roofing Code:Section 1507
1507.2.9.4, Crickets and Saddles:
A cricket or saddle shall be installed on the ridge side of any chimney or penetration greater than 30 inches (762 mm) wide as measured perpendicular to the slope. Cricket or saddle coverings shall be sheet metal or of the same material as the roof chimney.
This section implies that saddles are to be installed on steep-slope roofs at any penetration that is wider than 30 inches (762 mm). This includes chimneys, dormers, vents, skylights or any other roof curbs. The saddle or cricket shall be installed at the ridge side (upslope) and divert water from the penetration down the slope.
The cricket or saddle coverings shall be fabricated from sheet metal or a material similar to the roof construction for uniformity.
Waterproofing Code:Section 1807
Dampproofing and Waterproofing
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.
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, then 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.