N.Y.C. Admin. Code § PC 915: Section PC 915: Combination Waste and Vent System

915.1 Types of fixtures.

A combination waste and vent system shall not serve fixtures other than floor drains, lavatories and drinking fountains. Combination waste and vent systems shall not receive the discharge from a food waste disposer or clinical sink.

915.2 Installation.

The combination waste and vent system shall be a horizontal piping system. The only vertical pipe of a combination waste and vent system shall be the connection between the fixture drain and the horizontal combination waste and vent pipe. The vertical distance shall not exceed 8 feet (2438 mm).

915.2.1 Slope.

The slope at a horizontal combination waste and vent pipe shall not exceed one-half unit vertical in 12 units horizontal (4-percent slope) and shall not be less than indicated in

Table 704.1

.

915.2.2 Size and length.

The size of a combination waste and vent pipe shall be not less than that indicated in

Table 915.2.2

. The horizontal length of a combination waste and vent system shall be unlimited.

Table 915.2.2 Size of Combination Waste and Vent Pipe

Diameter Pipe (inches)

Maximum Number of Drainage Fixture Units (dfu)

Connecting to a horizontal branch or stack

Connecting to a building drain or building subdrain

2

3

4

2 1/2

6

26

3

12

31

4

20

50

5

160

250

6

360

575

For SI: 1 inch = 25.4 mm.

915.2.3 Connection.

The combination waste and vent system shall be provided with a dry vent connected at any point within the system or the system shall connect to a horizontal drain that serves vented fixtures located on the same floor. Combination waste and vent systems connecting to building drains receiving only the discharge from one or more stacks shall be provided with a dry vent. The vent connection to the combination waste and vent pipe shall extend vertically to a point not less than 6 inches (152 mm) above the flood level rim of the highest fixture being vented before offsetting horizontally.

915.2.4 Vent size.

The vent shall be sized for the total drainage fixture unit load in accordance with Section 906.2.

915.2.5 Fixture branch or drain.

The fixture branch or fixture drain shall connect to the combination waste and vent within a distance specified in

Table 909.1

. The combination waste and vent pipe shall be considered the vent for the fixture.