PART 7 — PLUMBINGUpdated for the 2024 Ontario Building Code
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7.5.8.3.Branch Vents, Vent Headers, Continuous Vents and Circuit Vents
(1) Branch vents, vent headers, circuit vents and continuous vents shall be sized in accordance with Table 7.5.8.3.,
unless they are individual vents or dual vents.
(2) For the purposes of Table 7.5.8.3., the length of a branch vent shall be its developed length from the most distant
sanitary drainage pipe connection to a vent stack, stack vent, header or open air.
(3) For the purposes of Table 7.5.8.3., the length of a vent header shall be its developed length from the most distant
sanitary drainage pipe connection to open air.
(4) For the purposes of Table 7.5.8.3., the length of a circuit vent shall be its developed length from the horizontal
sanitary drainage pipe connection to a vent stack, stack vent, vent header or open air.
(5) For the purposes of Table 7.5.8.3., the length of a continuous vent shall be its developed length from the vertical
sanitary drainage pipe connection to a vent stack, stack vent, vent header or open air.
Table 7.5.8.3.
Sizing of Branch Vents, Vent Headers, Circuit Vents and Continuous Vents(1)
Forming Part of Article 7.5.8.3.
Nominal Pipe Size of Vent Pipe, NPS
Total Hydraulic Load
Served by Vent Pipe, 1¼ 1½ 2 3 4 5 6 8
fixture units Maximum Length of Vent Pipe, m
2 9 NL NL NL NL NL NL NL
8 9 30 61 NL NL NL NL NL
20 7.5 15 46 NL NL NL NL NL
24 4.5 9 30 NL NL NL NL NL
42 NP 9 30 NL NL NL NL NL
60 NP 4.5 15 120 NL NL NL NL
100 NP NP 11 79 305 NL NL NL
200 NP NP 9 76 275 NL NL NL
500 NP NP 6 55 215 NL NL NL
1 100 NP NP NP 15 61 215 NL NL
1 900 NP NP NP 6 21 61 215 NL
2 200 NP NP NP NP 9 27 105 335
3 600 NP NP NP NP 7.5 18 76 245
5 600 NP NP NP NP NP 7.5 18 76
Notes to Table 7.5.8.3.:
(1) NP = not permitted and NL = not limited
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
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Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.