All roofs and paved areas, yards, courts and courtyards shall be drained into the stormwater sewerage system but not into sewers intended for sewage only. Where there is no sewer accessible, such connections shall be discharged into the public gutter, unless otherwise permitted by the proper authorities, and in such case need not be trapped.
A. 
No gutter or inside leader shall be of less size than the following:
Area of Roof
(square feet)
Gutter
(inches)
Leader
(inches)
Up to 90
3
1 1/2
91 to 270
4
2
271 to 810
4
2 1/2
811 to 1,800
5
3
1,801 to 3,600
6
4
3,601 to 5,500
8
5
5,501 to 9,600
10
6
B. 
Outside leaders to the frost line shall be one size larger than required in the above table.
C. 
Gutters eight inches or over in width on new buildings shall be hung with wrought iron hangers of approved type.
D. 
The above sizes of rain leaders are based on diameter of circular rain leaders, and gutters based on semicircular sheet metal gutters with the top dimension given and other shapes shall have the same sectional area.
When placed within the walls of any building or run in an inner or interior court or ventilating pipe shaft, all conductors or roof leaders shall be constructed of cast iron or galvanized wrought iron or steel pipe.
Where an existing sheet metal conductor pipe within the walls of any building becomes defective, such conductor shall be replaced by one which conforms to this article.
Conductor pipes shall not be used as soil, waste or vent pipes, nor shall any soil, waste or vent pipes be used as conductors. House or intercepting traps and fresh air inlets are prohibited in connection with house drains.
Overflow pipes from cisterns, supply tanks, expansion tanks and drip pans shall connect only indirectly with any house sewer, house drain or soil, waste or vent pipe.
Where subsoil drains are placed under the cellar floor or used to encircle the outer walls of a building, the same shall be made of open-jointed drain tile or earthenware pipe, not less than four inches in diameter, and shall be properly trapped and protected against back pressure by an automatic back pressure valve accessibly located before entering the storm sewer or drain. They may discharge through a cellar drain.