Drain pipe configuration question

[chrisharper80]

Hey all, my name is Chris and I'm new to the forum. Working on a bathroom DIY job. The tub surround was done incorrectly (normal drywall, no waterproofing under the tile and the backing didn't overlap the tub flange...as well as a non-waterproofed window with water leaking through the sill). I have demo'd everything and discovered that the bathtub drain was plumbed in strangely. There are 2 drain pipes coming up from the subfloor. One is the normal bathtub drain. The other one makes a bend into the wall cavity and goes up and turns left towards the sinks. Not 100% sure exactly where that one goes (maybe the sinks share the drain pipe?).

The problem is that this other drain pipe comes up exactly where the corner of the tub should sit. Looking at the old tub I removed, it looks like they just removed the 45-degree bracing piece from the side of the tub so this pipe sat in the hollow area of the tub. I'd really like to avoid doing that because it will make the tub flex a lot more than it should and likely lead to cracks the caulking around the tub flange.

Looking at how this is set up, I think I could switch these at the wye, run the P-trap directly across to the drain and drill a hole in the framing with an elbow to run straight up into the pipe. The single pipe connecting into the wye is directly under the wall cavity so an elbow up through the framing would run right into the wall.

Is there any problem with swapping the way these 2 lines come out of the wye? Any other ideas? I have attached several pics. Thanks in advance...plumbing isn't my strong suit.

 

[Cacher_Chick]

The pipe going up is the vent for the tub. The location of the floor joist is the challenge. The wye could be rolled up so the vent take-off is over a bit further, but looking at photos I cannot tell if that will fix your issue.

In any case, the vent cannot be removed and it does need to be vertical. It can be moved further down the line if there is a place for it.

 

[Sponsor]

 

[Terry]

Normally the vent would come straight up in that situation. You may be able to take a sawzall to that and open things up a bit. You need the vent.

 

[chrisharper80]

Ahhh I see. So if I cut an extra inch or two out of the floor toward the joist, then roll up the wye I just might be able to give myself enough room to get the tub in place. Since the vent is coming horizontally out of the wye, it seems like rolling up the wye would be better for the vent anyway. Putting a sanitary tee instead of a wye to the vent and drilling straight up through the 2x4 would be a big no-no...correct?

 

[Terry]

Code likes a wye fitting, but decades ago we were installing santees in that location.
The main reason for the wye fitting, is often someone comes along later and wants to use that pipe for a drain. A wye fitting is much better in that case.