The Ontario Building Code | Size Restriction Size Restriction

(1) The size of a branch vent, stack vent, vent stack or header shall be not less than the size of the vent pipe to which it is connected.

(2) Every sanitary building drain shall terminate at its upstream end in a stack of at least 3 in. size.

(3) A stack referred to in Sentence (2) shall be a soil stack if one is available and may be a vent stackor waste stack that provides at least 3 in. stack vent and that goes to open airabove the roof, either directly or through a header.