The Ontario Building Code | Terminals
(1) Except as provided in Sentence (3), the upper end of every vent pipe that is not terminated in open air shall be connected to a venting ="http://thehandyforce.com/interior/bathroom-renovations/" title ="Toronto Bathroom renovation inspiration">venting systemthat terminates through a roof to open air.
(a) no single change of direction of the vent pipe exceeds 45°,
(b) all parts of the vent pipe are nominally vertical,
(c) the vent pipe is increased to not less than 3 in. in sizebefore penetrating a wall or roof, and
(d) where the buildingis 4 storeys or less in height, the vent pipe terminates above the roof of the building.
(4) Except for a fresh air inlet, where a vent pipe is terminated in open air, the terminal shall be located,
(a) not less than 1 000 mm above or not less than 3.5 m in any other direction from every air inlet, openable window or door,
(b) not less than 2 000 mm above or not less than 3.5 m in any other direction from a roof that supports an occupancy, and
(c) not less than 2 000 mm above ground.
(5) Where a vent pipe passes through a roof, it shall,
(a) be terminated high enough to prevent the entry of roof drainage but not less than 150 mm above the roof or above the surface of storm water, which could pond on the roof, and
(b) be equipped with flashing to prevent the entry of water between the vent pipe and the roof or the wall.
(6) Where a vent pipe passes through a roof or an outside wall of a building, it shall be protected from frost closure by increasing its diameter at least one size, but not less than 3 in. in size, immediately before it penetrates the roof or the wall.
(7) Where a vent pipe is located 2 000 mm or more above a roof, it shall be so constructed as to be stable and secure.
(8) Flashing shall be of material specified in Article 22.214.171.124. and on a shingled roof shall have a minimum dimension of 500 mm by 500 mm.
(9) Where a sleeve flashing is installed on a flat roof, it shall extend at least 150 mm above the flood level and on a sloped roof shall be at least 150 mm high on the short side.
(10) No bore of a vent stack or stack vent shall be reduced or obstructed by the installation of a flashing.
7.5.7. Minimum Size of Vent Pipes