12-06-2008, 09:30 PM
I'm remodeling a second floor half bath into a full bath. The new shower and lav are vented through the roof and the drain runs inside the wall of the first floor to the basement. I would like to connect this drain to the drain line from the kitchen sink, which is vented through the roof and also runs to the basement. Is this OK? I'm not completely convinced that its a good idea to connect a second floor drain to a first floor drain in this manner. I have attached an illustration. Green is the current plumbing and white is the new plumbing for the shower and lav. All pipes are 2 inches unless indicated otherwise.