How many bathrooms can be connected on a 3 inch vertical stack?
Referring to the International Plumbing Code, a bathroom group requires 5 Drainage Fixture Units.
As a horizontal branch 3&quot; is good for 20 DFU's or 4 bathroom groups.
In vertical stacks the number goes up with multiple branches but each single branch is limited to 20 DFU's
Good Luck and check the tables here:
https://codes.iccsafe.org/content/IPC2018/chapter-9-vents