In Mass. Is it OK to have one 2" stack with kitchen sinks on the first and second floor tied in, with no separate venting? Or does the first floor sink need a vent pipe that attaches to the stack above the sink level on the second floor?

Let's ask a Mass plumber. Mark?
You around?

Hi all:

I'm sorry to say that in Mass. and anywhere else I know of, you need to have an individual vent for that 1st floor sink and it must connect at a minimum of 6 inches above the flood level rim of the kitchen sink on the 2nd floor.

One option that could help is an automatic air vent... or AAV. An AAV is a mechanical vent that eliminates the need to run that 1st floor vent, but unfortunately, it is ABSOLUTELY ILLEGAL in Massachusetts, so I don't recommend it, but I wanted you to know about these in case you hear about them from others is all.

Any questions, let us know...

Mark