(1)
The nominal pipe size of a branch vent, stack vent, vent stack or vent header shall be not less than the nominal pipe size of the vent pipe to which it is connected.
(2)
Sanitary building drains shall be provided with at least one vent that is not less than NPS 3.
(3)
A vent referred to in Sentence (2) shall be a soil stack if one is available and may be a vent stack or waste stack that provides at least NPS 3 stack vent and that goes to open air above the roof, either directly or through a header.