The Ontario Building Code | Vent Stacks
220.127.116.11. vent Stacks
(3) The vent stack required by Sentence (1) shall be connected to a vertical section of the soilor waste stack at or immediately below the lowest soil or waste pipe connected to the soil or waste stack.
(4) Fixtures may be connected to a vent stack provided,
(a) the total hydraulic load of the connected fixtures does not exceed eight fixture units,
(b) at least one fixtureis connected to a vertical portion of the vent stack and upstream of any other fixtures,
(c) no other fixtureis connected downstream of a water closet,
(d) all fixturesare located in the lowest storey served by the vent stack, and