Started bathroom remodel and found some off kilter plumbing

[Noah Simpson]

Hello,

I started a remodel on my master bath. This is second floor, 2X10 joists. Attic above. I'm in Hillsborough, NC, and the county is on IPC.

There was a mechanical coupler where the yellow line is drawn connecting a PVC shower trap and drain to the original ABS plumbing. Based on my diagram, maybe you WILL believe what came out of it when I pulled it off. At that point I pulled up the subfloor that you can see removed in my photo. Suffice to say it looks wrong, but I'm trying to figure how to fix it.

The green line drops down to the kitchen sink, and I assume it is supposed to be a vent, but I think prettymuch this whole bathroom had been draining down it instead of the main drain (which is 3" pipe that turns downward with an elbow you can see in the back of the second photo

I've already cut most of this plumbing away and repaired the joists.

I could move the toilet to the opposite wall from it's current location and run 3 inch horizontal to the drain stack. In it's current location i'm not sure how I have room to make the turn and go down. they used a san-T on it's side.

The shower drain will be centered, I'll bring the line through the joists, then 45 turn, then into a wye into the horizontal 3" pipe. And essentially do the same with the line from the sink (red). Green line will be disconnected from all this, and connect to a new vertical pipe up to the attic and tie into the vent lines up there.

My question is about vents. I can easily connect the vent indicated by the white line to the new shower waste line, but I'm not sure if it's allowed to run horizontally under the floor like that.

I could do the same for the toilet and add a vent in the wall for it as well, but it's the same question.

The sink (red) is 2 inch pipe. Can it just act as a wet vent for the whole bathroom? In which case I don't need to reconnect the white vent at all?

Two adjacent studs on the exterior wall were hacked completely through for the double sink drains on an old vanity, it looks like. and then when converted back to a single sink vanity that PVC turn was added. I'll cut that away and sister on new studs, and connect with a san-T for a single sink vanity right there.

I think the copper is original for the house, built in 1981. Should I be replacing that while I have the walls off? I'd be replacing with pex.

 

[Noah Simpson]

I drew up what I'm proposing to change it to. I can't move the water closet to the opposite wall after all, since I guess the shower door is better on the same side as the shower fixture. I can move it 3" further from the drain stack, which I hope will give me room to use a wye.

I think this is a correct wet vent. But I wasn't totally sure if the adapter from 3" to 2" is okay in that spot?

 

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[Reach4]

Are your arrow directions in https://terrylove.com/forums/index.php?attachments/img_20210502_151825706-jpg.73619/ intended to represent something?

In proposedNewSinkLine.jpg you are trying to drain from a lavatory? I would think you would only use ABS for glued stuff. Why not have a trap adapter at the wall, and do the rest of the path from the lavatory drain with slip joint stuff?

It would have been better to have a 2x2x1.5x1.5 double fixture fitting rather than the 2x2x2x2.

Is that an outside wall with 2x4s (3.5 inch)?

 

[Noah Simpson]

The arrows just indicate the direction of the slope on those pipes. Everything in the photos is just what I found when I uncovered the floor. The Lines I have drawn on the photos in the second post are indicating what I want to install when I've cut the existing abs away.

I will only have 1 sink on the vanity, so I will just cut all that away and have a single 2" pipe coming out of the wall off that vertical. What's there still has to be removed to repair those studs.

Yep, that's an outside wall. Roof trusses bear on it.

 

[Reach4]

The arrows just indicate the direction of the slope on those pipes. Everything in the photos is just what I found when I uncovered the floor.

So the blue and white arrows represent problems to be fixed.

I will only have 1 sink on the vanity, so I will just cut all that away and have a single 2" pipe coming out of the wall off that vertical. What's there still has to be removed to repair those studs.

So instead of that double fixture fitting, I think you would want a 2x2x1.5 sanitary tee. Then have a 1.5 trap adapter at the wall. Put a reducing washer at the trap adapter, and use a 1-1/4 trap, or put the reducing washer at the tailpiece and use a 1.5 slip joint trap. Then there is no need for the big notches.

Yep, that's an outside wall. Roof trusses bear on it.

You might want to increase that wall thickness to 5.5 inches with 2x6s You would screw and glue the 2x6s along side of the 2x6s maybe. You need a carpenter or engineer to help I think. The thicker wall would leave some room for insulation. XPS would give better insulation.

 

[Noah Simpson]

Yep, basically everything that should have been draining was just sitting where the yellow and grey arrows come together.
Good call, I will get the 2X2X1.5" sanitary tee.

The house does have a 1" layer of EPS between the sheathing and studs, so that's good. It wouldn't be too difficult to sister on 2X6s, since the wallboard is off anyway.