The Ontario Building Code | Additional Circuit Vents and Relief Vents Additional circuit Vents and Relief vents

(1) Except as provided in Article and in Sentence, the minimum size of an additional circuit vent or relief vent installed in conjunction with a circuit vent is permitted to be one size smaller than the required size of the circuit vent, but need not be larger than 2 in.

(2) The size of the soilor waste pipe acting as a relief vent in accordance with Sentence shall be in conformance with Table, or or Article, whichever size is the largest considering the hydraulic load drained into the soil or waste pipe.