Div. B › Part 7 › 7.5 › 7.5.4 — Vent Pipes for Soil or Waste Stacks

7.5.4.2 — Vent Stacks

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(1) Except as provided in Sentence (2), every soil or waste stack draining fixtures from more than 4 storeys shall have a vent stack.

(2) A soil or waste stack that serves as a wet vent does not require a vent stack.

(3) The vent stack required by Sentence (1) shall be connected to a vertical section of the soil or waste stack at or immediately below the lowest soil or waste pipe connected to the soil or waste stack.

(4) Fixtures may be connected to a vent stack provided,

(a) the total hydraulic load of the connected fixtures does not exceed eight fixture units,

(b) at least one fixture is connected to a vertical portion of the vent stack and upstream of any other fixtures,

(d) all fixtures are located in the lowest storey served by the vent stack, and

(e) the section of the vent pipe that acts as a wet vent conforms to the requirements regarding wet vents.

OBC Definitions

Defined terms on this page

fixture

means a receptacle, plumbing appliance, apparatus or other device that discharges sewage or clear water waste, and includes a floor drain.

fixture unit

means , when applied to a drainage system, the unit of measure based on the rate of discharge, time of operation and frequency of use of a fixture that expresses the hydraulic load that is imposed by that fixture on the drainage system.

soil

means , except for the purposes of Part 8 of Division B, a portion of the earth’s crust that is fragmentary or such that individual particles of a dried sample may be readily separated by agitation in water, and includes boulders, cobbles, gravel, sand, silt, clay and organic matter.

storey

means , except for the purposes of Part 7 of Division B, the portion of a building, (a)that is situated between the top of any floor and the top of the floor next above it, or (b)that is situated between the top of the floor and the ceiling above the floor, if there is no floor above it.

vent pipe

means a pipe that is part of a venting system.

vent stack

means a vent pipe that is connected at its upper end to a header or is terminated in open air and that is used to limit pressure differential in a soil or waste stack.

waste pipe

means a sanitary drainage pipe that carries the discharge from a fixture directly to a waste stack, soil stack, sanitary building drain, branch or sewage system.

waste stack

means a vertical waste pipe that passes through one or more storeys and includes any offset that is part of the stack that conducts liquid waste from fixtures other than sanitary units.

wet vent

means a waste pipe that also serves as a vent pipe.

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