Replacing tub with shower pan

[geniescience]

and you really really cannot add another P-trap in series with an existing one.

[marc4790]

Well, I did keep digging and found a 2 inch P-trap with a 1 1/2 inch straight pipe attached via an adapter. I dug out all of the sand around it so I would have room to work.I also drilled and made an access through the slab at the center of the shower stall. I then cut off the trap at the point where it connected to a 2 inch straight pipe. I solvent welded a 2 inch sanitary 90 degree ell and brought a straight section of pipe to the center of the shower slab. At that point I connected a 2 inch P-trap and then a vertical 2 inch sched. 40 pipe to 1/2 inch above the slab. The pipe was plumbedand then was plugged with a rag until I finish the blocking and framing. I packed the sand back in the whole up to the slab and compacted it firm with a 2x4.
I feel better now that I found the P-trap and moved it's location to right below the 2 inch Oatey drain. Thanks again gentlemen. I have worked in emergency medicine for over 40 years, so if I can return the favor please e-mail me directly for any questions or advice.
marc

[marc4790]

I have chiseled out the concrete slab to center the drain. That was quite a job.I am ready to remopve the tub P-trap and move the new drain to the center of the shower floor. My questions aare:
1) At what height do I attach the new PVC drain and trap,(I will be using a PVC shower pan after I apply a dry mud bed over a Thinset bonding to the slab);
2) How can I predetermine the height of the Oatey drain so that it is seated properly considering that I will be using a preslope deck mud, PVC liner, then anotherr deck mud base, then tile;
3) Is there a minimum height /depth of the vertical pipe from the shower drain to the P-trap, ( is there a required distance of vertical drop);
I know that for the horizontal pipe I must have 1/4 inch per foot of run to the main waste pipe. This is not as easy as it looks on This Old House!
marc

[jadnashua]

There is a maximum depth of the trap (too much velocity), but there is no minimum depth of the trap. The thickness of the preslope under the drain isn't a big problem if it is on a concrete slab - but they like something like 3/4" or so. If you go over to www.johnbridge.com and check out the "Liberry", there's a detailed discussion on this topic.

[marc4790]

Thanks Jim. I will check out that posting in the "Liberry"
Marc