The Ontario Building Code | Vent Pipe Connections
184.108.40.206. vent pipe Connections
(1) Every vent pipe in a plumbing system shall be installed so as to be direct as possible to a vent stack or open air, as the case may be, and so that any horizontal run below the flood level of the fixture to which the vent pipe is installed is eliminated where structurally possible.
(2) Except for wet vents, where a vent pipe is connected to a nominally horizontal soil or waste pipe, the connection shall be above the horizontal centre line of the soil or waste pipe.
(3) Unused vent pipes installed for future connections shall be permanently capped with an end cleanoutor an adapter and plug.