Add 2nd floor bathrrom - DWV

Hello. I have searched and read numerous items (here and elsewhere) about DWV, but I must be dense because it is still very vague to me. I am just trying to get a handle on this situation before seeking out a contractor. I am in Sacramento, California. It is a slab house. There is an existing bathroom on the first floor relatively under the proposed location for the new bathroom. The existing bathroom has a two bowl sink, toilet, tub, and separate shower. I have no idea how the drain/waste is hooked up (the toilet, sink, and tub are on a common interior wall - shower on a different wall about 8 feet away), but it is a relatively new house (2000), so I would hope everything is to code. With regard to venting, the only thing I find in the attic is a single 2" vent.

I want to add a 2nd floor bathroom. It would have a one bowl sink, toilet, and shower. My main goal is avoid having to open the slab. To the extent possible, avoiding opening existing walls and additional roof penetrations would also be nice. However, I realize the existing 1st floor wall most likely has to be opened.

Any thoughts, ideas, or help are greatly appreciated.

Regards,

Tom

Yes, you will need to open up the floor and find a 3" or 4" line that you can wye into.
The wye must be down line from the other plumbing fixtures.
You can't run waste lines from above into the traparms of the fixtures below.
It may be possible to locate the waste outside the foundation, and perhaps wye in there.

The vent from the downstairs will need to make it's way through the roof too.

Thanks for the information. Having to cut the slab puts the whole project in doubt.

Tom

Dwv

Why? That may be the easiest part of the whole project.

Because the project is to finish what is currently an unfinished loft/attic and there was going to be no other first floor work happening. We thought about adding the 2nd floor bathroom because the existing hot and cold water and the existing vent are very conveniently located. I new that the waste line would be an issue. I was hoping we could get away with just cutting into the existing first floor wall. Now we have to decide if we want to rip up the floor in the existing bathroom where we were originally not going to touch the floor.

Thanks, Tom

floor

Depending on which way the sewer runs from the "vent" pipe, breaking the floor in the bathroom might be the wrong place to do it. You might have to cut the floor in the adjacent room.

That would likely be in the master bedroom closet then. The existing toilet is the fixture furthest toward the sewer line. Is there a general rule of how far away from the existing connection you need to be for making the new "tap".

Thanks for the good information. It will be helpful when we are getting quotes.

Tom