Indiana Administrative Code
Title 675 - FIRE PREVENTION AND BUILDING SAFETY COMMISSION
Article 15 - INDUSTRIALIZED BUILDING SYSTEMS
Rule 2 - Indiana Mobile Structures Code
Section 2-62 - Size of vent piping

(a) Main Vent. The drain piping for each toilet shall be vented by a one and one-half inch (1 1/2") minimum diameter vent connected to the main drain by one of the following methods:

(b) Individual Vents. Unless protected with an anti-siphon trap vent device, each individually vented fixture with a one and one-half inch (1 1/2") or smaller trap shall be provided with a vent pipe equivalent in area to a one and one-fourth inch (1 1/4") nominal pipe size. The main vent, toilet vent and relief vent, and the continuous vent of wet-vented systems shall have an area equivalent to a one and one-half inch (1 1/2") nominal pipe size.

(c) Common Vent. When two fixture traps located within the distance allowed from their vent have their trap arms connected separately at the same level into an approved double fitting, an individual vent pipe may serve as a common vent without any increase in size.

(d) Intersecting Vents. Where two (2) or more vent pipes are joined together no increase in size shall be required; however, the largest vent pipe shall extend full size through the roof.

(e) Distance of fixture trap from vent shall not exceed the values given in Table 2B, below.

(f) When a combination of two (2) or more water closets, sinks, showers, urinals, or clothes washing equipment are installed the Indiana plumbing code (675 IAC 16-1 [675 IAC 16-1 was repealed filed Sep 22, 1988, 2:35 p.m.: 12 IR 341, eff Jan 2, 1989. See 675 IAC 16-1.2.]) shall apply for mobile system-commercial transitory.

TABLE 2B