I am trying to put in a bathroom on the 2nd floor of my cape cod. Currently there is piping for a toilet and a cold water supply on the one end of the bathroom near the stack. Why they only put in a toilet i have no idea. I am trying to put a sink and shower on the other side of the bathroom 9 feet away. The joists are 2x8's 16 inches on center and run perpendicular to the direction i would need to run the waste and supply lines for the sink and shower. For a 2inch waste line going 9 feet there is no way that i can keep the hole more than 2 inches from either edge of the joist for the whole run. None of the plumbers seem terribly concerned about this. Does anyone have advise on options? Does sistering the joists allow you to go closer to any of the edges?
The other option is to put a second waste line on the other end of the "bathroom". I have a closet below the side of the bathroom that i want to put the sink and shower. Is a 2 inch waste line ok to drop down into my basement? I would then have to somehow tie that into a 4 inch cast iron main stack right where it exits the house. How difficult is that? Thanks