The Ontario Building Code | Fixtures Draining into Vent Pipes
7.5.4.5. Fixtures Draining into vent pipes
(1) The trap arm of a fixturethat has a hydraulic load of not more than 1 ½ fixture units may be connected to the vertical section of a circuit vent, additional circuit vent, offset relief vent or yoke vent, provided that,
(a) not more than two fixtures are connected to the vent pipe,
(b) where two fixturesare connected to the vent pipe, the connection is by means of a double fitting, in accordance with Table 7.2.4.5., and
(c) the section of the vent pipe that acts as a wet vent conforms to the requirements regarding wet vents.
7.5.5. Miscellaneous vent Pipes
In Plain Language
A fixture's trap arm can drain into a vent pipe under specific conditions set out in this article, allowing certain vent pipes to double as drainage in a limited, controlled way.
This is a plain-language summary of the 2012/2017 Ontario Building Code text above, for general understanding only and not a substitute for the Code. Always confirm current requirements against the 2024 edition (O.Reg. 163/24) or a qualified professional before construction.