N.Y.C. Admin. Code § PC 904: Section PC 904: Outdoor Vent Extensions

904.1 Required vent extension.

The vent system serving each building drain shall have not less than one vent pipe that extends to the outdoors.

904.1.1 Installation.

The required vent shall be a dry vent that connects to the building drain or an extension of a drain that connects to the building drain. Such vent shall not be an island fixture vent as allowed by Section

916

.

904.1.2 Size.

The required vent shall be sized in accordance with Section 906.2 based on the required size of the building drain.

904.2 Vent stack required.

A vent stack shall be required for every drainage stack that has three branch intervals or more

.

904.3 Vent termination.

Vent stacks or stack vents shall terminate outdoors above the roof or to the stack vent portion of the soil or waste stack, at least 6 inches (152 mm) above the flood level of the highest fixture connection discharging into the soil or waste stack.

904.4 Vent connection at base.

Vent stacks shall connect to the base of the drainage stack. The vent stack shall connect at or below the lowest horizontal branch. Where the vent stack connects to the building drain, the connection shall be located downstream of the drainage stack and within a distance of 10 times the diameter of the drainage stack.

904.5 Vent headers.

Stack vents and vent stacks connected into a common vent header at the top of the stacks and extending to the open air above the roof at one point shall be sized in accordance with the requirements of Section 906.1, but shall not be smaller than the smallest stack vent. The number of fixture units shall be the sum of all fixture units on all stacks connected thereto, and the developed length shall be the longest vent length from the intersection at the base of the most distant stack to the vent terminal in the open air, as a direct extension of one stack.

904.6 Sub-stack connections.

Where it is desired to terminate stacks at a point below the roof terminus of the main vent stack, the sub-stack may connect to the main vent stack provided the portion of the main vent stack above the connection is sized for the total fixture unit load connected thereto, and for the maximum developed length of the stack or sub-stack.