(1)
Except as provided in Sentence (2), every stack that drains fixtures from more than 4 storeys containing plumbing fixtures shall have a vent stack.
(2)
A 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 stack at or immediately below the lowest sanitary drainage pipe connected to the stack.
(4)
Fixtures are permitted to be connected to a vent stack, provided
(a)
the total hydraulic load of the connected fixtures does not exceed 8 fixture units,
(b)
at least one fixture is connected to a vertical portion of the vent stack and upstream of any other fixtures,
(c)
no other fixture is connected downstream of a water closet,
(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.