Replacing tub with shower pan

**marc4790** · 06-11-2006, 08:03 AM

Hello. I have removed the tub and am in the process of constructing walls for a walk-in shower. My plumbing question is:
Do I need to install a P-trap to the existing tub drain below the slab or can I safely assume that a trap was installed when the tub was set? The 2 inch pipe seeems to comes straight up from a sand bed below the slab, but I can not see below unless I dig down into the saand below the slab. there is a 9 inch by 12 inch opening in the slab around the pipe.
Thank you for sharing your time,
marc

**jimbo** · 06-11-2006, 09:28 AM

The tub surely had a trap. You have a problem here, in that the tub drain is 1½" and code requires 2" for the shower.

**marc4790** · 06-11-2006, 03:23 PM

Hi Jimbo, thanks for the reply. The drain is 2 inches. I measured it and bought two 45 degree ells and two inch pipe to bring it out away from the head wall.
marc

**jadnashua** · 06-11-2006, 03:42 PM

The trap should be directly under the drain...

**marc4790** · 06-11-2006, 06:06 PM

Thanks Jim. Should I dig out around the drain to find the trap? I did remove the one and a half section that was attached to the tub via an adapter or reducer from the two inch pipe that comes out of the ground below the slab. I cut the adapter that was glued onto the two inch pipe, just below the reducer, but now must raise the height aabove the slab and bring it out away from the wall to get it above the sloped deck that I will form in preparation for the membrane.
marc

**jadnashua** · 06-11-2006, 07:04 PM

You'll probably have to break up some slab. Move the p-trap so it is under the center of your shower pan and you have the proper slope (1/4"/foot) back to the main line.

**marc4790** · 06-11-2006, 08:17 PM

Jim, is it necesaary to move it to the center, (that would mean moving it 3 feet instead of about 4 or 5 inches. Couldn't I just slope the bed to the end of the 33 inch by 56 incht shower stall? That would save a lot of work breaking through the slab, refilling it and moving the P-trap? Of coursee if it necessary, I will do what is best.
marc

**jadnashua** · 06-11-2006, 08:32 PM

The drain needs to be low enough so that you end up with 1/4" per foot from the furthest wall. So, if it is say 4' away from the furthest wall, you need it to be 1" below the floor level there. Now, also, to look professional, your floor height should be even all the way around the shower. This means that you will have a 1" fall from the short wall distance to that drain, not good. Check out www.johnbridge.com and read their shower construction info in the "liberry" (sic); it will help answer your tiling questions. The guys here can help you get the drain connected.

There are some neat alternatives to a "traditional" shower construction. Check out Kerdi from www.schluter.com. It solves problems you didn't know you had, and is a neat way to go.

**marc4790** · 06-12-2006, 06:03 AM

OK then Jim. I will do as you advise. As for the Kerdi shower, money is always an issue; I am a minister and do a lot of volunteer work for our elderly poor helping them with home repairs, so I live on very little. This renovation has to be affordable. That is one reason why I am doing it myself,besides the fact that we live in a small rural area that does not have any craftsmen/women.
But, I will first dig down to find the old P-trap, then break out the slabonly enough to run 2 inch PVC pipe and new P-trap to the center of the pan.
How can I determine at what height to set the Oatey drain so that it will be at the correct height once the pre-slope, membrane and final deck mud are in place?
marc

**jadnashua** · 06-12-2006, 07:52 AM

The traditional shower construction has worked for a long time, so you should be fine if you follow the instructions. Suggest you ask your height question over on the www.johnbridge.com site. The info in their "liberry" covers it all, and you can ask tiling specific questions there as well. As a reference, the layers would be: deck mud for pre-slope, liner, final deck mud (constant thickness), thinset and tile. On the walls, a vapor barrier, then cement board (cbu). Tape the seams with the alkali resistant tape (do it as you tile) and thinset and tile. No screws or nails in the cbu through the liner. Run the cbu down over the liner before you put in the final slope so that top layer holds the bottom of the cbu in place. Make sure there is blocking behind the cbu near the bottom so it doesn't just flop around. Good luck.

**marc4790** · 06-12-2006, 08:29 AM

Hi Jim and thanks again. I have placed 2 x 12's between the wall studs for both blocking and attachment of the membrane. I plan to use a 6 mil.plastic vapor barrier under the Durock, then tape the seams as you advise. I also want to paint the seams with Red Guard to assure protection, ( I don't want to do this again.) My biggest challenges now is breaking through the slab and then getting the membrane to fit well enough not to interfere with the placement of the Durock. As we have a second bathroom, I intend to take my time and do the best that I can.
marc

**jadnashua** · 06-12-2006, 12:48 PM

Suggested order of things:

blocking
drain centering
preslope
membrane
vapor barrier
cbu
final slope
tile (some people like to do the walls first, then the floor, but it doesn't matter. If you want the floor tile to go under the walls, you can do all of the walls except the bottom row, do the floor, then the last wall row)
grout
sealer
shower

**marc4790** · 06-12-2006, 05:53 PM

Many thanks for all of your help Jim.
marc

**marc4790** · 06-13-2006, 07:27 AM

Hi Jim et.al. I made a mistake in measuring the drain after I removed the tub. It is actually a 1 1/2 inch that goes straight down into the sand and below the slab. I dug down about 6 inches, but could not find a p-trap. The former owner was a building contractor. Can I safely assume that the trap is don below the slab close to the septic tank where I cant reach it? Will I do any harm by putting in another for the tub to shower stall conversion?
Thanks in advance,
marc

**jadnashua** · 06-13-2006, 10:10 AM

Well, to pass code, you will need to keep digging and follow that pipe back. A shower requires a 2" drain, and you can't just increase the pipe diameter at the trap, you can go bigger, but not in that direction.

Some contractors don't build things like they are supposed to be done...