Exception: Limited area sprinkler systems installed in accordance with Section 903.3.8 of the building subcode, shall be water pressure rated not less than 160 psig at 73[degrees]F.
Two lavatories and two bathtubs or showers back-to-back may be installed on the same horizontal branch with a common vent for the lavatories and with no back vent for the bathtubs or shower stalls provided the wet vent is 2" in size and the lengths of the tub/shower drains conform to Table 12.8.1.
EXCEPTION: The water closets in bathroom groups shall not be required to be back vented if the following conditions are met:
Section 13.1.10.2 Overflow Roof Drainage
Where parapet walls extend or other construction extends above the roof, creating areas where storm water would become trapped if the primary roof drainage system failed to provide sufficient drainage, an overflow roof drainage system consisting of *scuppers*, standpipes, or roof drains shall be provided. The capacity of the primary system shall not be considered in the sizing of the overflow system.
N.J. Admin. Code § 5:23-3.15