July 26, 2018
Re: Vent Stack and Vent Header
The project is a high rise building with a plumbing system serving multiple residential suites. Due to the height of the building and the chosen design of the plumbing system, the plumbing system is required to be separated in to vertical zones. The design of the plumbing system proposes that a stack vent for a lower zone wet vented stack connects in to the vent stack of an adjacent soil or waste stack near the middle of the building.
Applicable Code Requirement
Sentences 184.108.40.206.(1), 220.127.116.11.(1) and 18.104.22.168.(1) of Division B of Book II (Plumbing Systems) of the 2012 British Columbia Building Code.
22.214.171.124.(1) Except as provided in Sentence (2), every soil-or-waste stack draining fixtures from more than 4 storeys shall have a vent stack.
126.96.36.199.(1) Branch vents, vent headers, circuit vents and continuous vents shall be sized in accordance with Table 188.8.131.52., unless they are individual vents or dual vents.
184.108.40.206.(1) A vent stack or stack vent shall be sized in accordance with Table 220.127.116.11. based on
a) the length of the vent stack or stack vent, and
b) the total hydraulic load that is drained to the lowest section of soil-or-waste stack or stacks served by the vent pipe, plus any additional vent loads connected to the vent stack or stack vent.
Decision being Appealed (Local Authority’s Position)
The local authority has determined that a vent stack is required for the soil or waste stack. The plumbing system, as designed, has the stack vent from an adjacent wet vented soil or waste stack connecting to the vent stack, which becomes a vent header, and from that point on replaces the vent stack required by Sentence 18.104.22.168.(1).
The appellant maintains that a vent stack has been provided, and the vent stack is also serving as a vent header. The vent is sized adequately for the total length and connected fixture load, using the more restrictive of the applicable vent sizing tables referenced in Sentences 22.214.171.124.(1) and 126.96.36.199.(1), and therefore complies with code.
Appeal Board Decision # 1813
It is the determination of the Board that the portion of the plumbing system as designed, which includes the stack vent from an adjacent wet vented soil or waste stack connecting to the vent stack, is compliant with the Code.
Reason for Decision
A vent header, by definition, inherently includes and may function as a vent stack. Sentence 188.8.131.52.(2) requires that for the purpose of Table 184.108.40.206., the length of a stack vent or vent stack shall be its developed length from its lower end to outside air. This supports that the vent stack is an inherent part of the vent header.
Per Sentence 220.127.116.11.(1) of Division A:
“Vent header means a vent pipe that connects any combination of stack vents or vent stacks to outside air.”
The sizing of a vent header must be in accordance with Sentence 18.104.22.168.(1) and Table 22.214.171.124., which is more restrictive than Sentence 126.96.36.199.(1) and Table 188.8.131.52., which is required to size vent stacks or stack vents.
The code has no provision which restricts the location of a vent header within the building.
Chair, Building Code Appeal Board