Tub to shower conversion, drain dilemma

[MCTMike]

Hi all,

I'm starting a conversion from a tub to a shower in a 40-year-old home. The tub has been removed, and I'm pondering what to do with the drain. Here's what I see after removing the tub:





The drain pipe fits loosely into a fitting in the concrete. I can pull the drain assembly out of the fitting easily, leaving an inch and a half wide hole.






The opening is just a little too small for the 1¼" PVC from Lowe's, which has a 1 ⅝" O.D.



My goal is to build a shower pan and connect a linear drain to the drain hole at this end. But the hole is so close to the wall that I'm worried about making it fit. I experimented with putting a bushing on the 1¼ to make it 1½, and then a coupler to make it 2", and then a couple of elbows to move it away from the wall, but then it's far too high - like four inches above the concrete slab.

I really don't want to have to rent a jackhammer and go deeper, but I'm afraid I might be running out of options. Any ideas?

 

[Twowaxhack]

You need to dig that tub box out and find the ptrap. You don’t need a jackhammer to do that.

Looks like your water pipe is out of the stud cavity.

Once you do that, take some more pics. You can’t use 1.25” pipe.

It needs to be 2” and a minimum under special situations,1.5” is acceptable.

 

[MCTMike]

Thanks for that. What's the best tool to dig it out? I had assumed the remaining material was concrete, but I could be wrong.

 

[Twowaxhack]

Thanks for that. What's the best tool to dig it out? I had assumed the remaining material was concrete, but I could be wrong.

Flat bar and hammer to start or a shovel maybe. It’s probably poured tar sealing the hole.

You’ll have to start the work and see what they sealed the hole with. Hard to tell everything from a pic on my iPhone.

 

[TomFOhio]

Thanks for that. What's the best tool to dig it out? I had assumed the remaining material was concrete, but I could be wrong.

I would use a heavy hammer and a chisel. Just be careful you don't hit the pipe.

 

[MCTMike]

I've dug down quite a ways through what was indeed tar. Here's what I'm looking at now: do I need to keep going until I get to something horizontal?

 

[Twowaxhack]

Ideally you want to find 2” horizontal pipe and then connect to that. You’ll find a ptrap down there. You probably will want to cut that off and relocated the drain.

Be careful and don’t cut or damage your water lines. A sawazall will cut them quickly if your blade slips or you let the blade extend into dirt and cuts a pipe you can’t see. Be careful

 

[MCTMike]

Finally got all the way down to the p-trap!

 

[MCTMike]

So if I understand right, my next step is to plumb new PVC to bring a new 2" drain up to the top of the hole, and then filling the hole. Should I use concrete for that, or the same mix that's used to build the shower pan? And where should my new drain PVC come up to?

 

[Twowaxhack]

Is that trap and horizontal pipe 2” ?

 

[MCTMike]

I cut into the horizontal just left of the trap. The horizontal pipe is 2" I.D.

 

[Twowaxhack]

Good deal. Now pipe your ptrap to its proper location and stub up 2” out of your trap. Clean that pipe with some alcohol or buy some pvc cleaner. Make sure you make up proper joints or you’ll be jackhammering out your new tile soon.

You’ll have to figure out at what elevation your shower drain needs to be. You doing the tile work ?

Once you complete the piping you can fill that hole in with fill dirt then cap it with pouring tar or cement.

Some people treat the disturbed dirt with termite spray. If you have a termite bond, call then and ask.

 

[Twowaxhack]

After your pvc joints cure you could drag a water hose in there and do a leak test. Stick the hose in the stub up and let it run for a few minutes..

 

[MCTMike]

Yes, I'm planning to do all the work myself: initial bed, waterproof wrap, upper bed, drain, tiling.

 

[MCTMike]

Good news: making progress.

Bad news: I may have made a critical error.

I decided to include the Kerdi bench in the design, and thought I should set it solidly on the slab and into cement board before building the shower pan. So here's what I've done, in order:

1. Installed cement backer board on three sides
2. Applied mortar with notched trowel to concrete slab and two sides of backer board
3. Set bench into mortar and scraped away excess.
4. Built brick wall curb to create fourth side of shower, aligned with front side of bench
5. Created sloped shower pan

I'm now realizing that I have complicated the job of putting down the vinyl membrane, which ought to be up behind the backer board, and not in front of it.

What's my next step? Am I in trouble?