The minimum required pipe size for water closets or pedestal urinal branches and stacks shall be 4 inches (100 mm).
Exception: A building three stories or less in height may utilize a 3-inch (75 mm) soil stack and 3-inch (75 mm) horizontal soil branches when not exceeding 48 fixture units, with not more than six water closets per soil stack and not more than three water closets per horizontal soil branch.
The minimum required pipe size for underground branches from downspouts, floor drains, laundry trays and sink stacks shall be 2 inches (51 mm).
(Amend Coun. J. 10-14-21, p. 37722, Art. VII, § 11; Amend Coun. J. 12-14-22, p. 58278, Art. VI, § 17)