Guys,
I am doing a new construction shower drain, and you guys convinced me to use the Schluter system of Kerdi mat. One complication, my drain is already installed and attached to the plywood substrate. I can screw the drain top (#3 in picture) or remove the top flange (#2) to mate with the Kerdi drain. However, I cannot move (nor do I want to) the base drain (#1) as it is tied to the plumbing below the plywood. Cutting out the plywood would be a real pain.
Does the Kerdi drain work with me backing out either #2 or #3 parts below, or must I cut out the base drain (#1)?
Replies
Have you looked at the cd that came with the drain system? It was in the box with the drain the last time I bought one.
Either that or go to thier web site and search through the videos to see if you can.
I would undo #2 and #3 and see if you can get the drain to fit. See if you can glue or sylicone the kerdi flang drain into place. The grill has a 1/4 inch play to align the tiles.
The Kerdi drain will not work with any of the drain assembly that you show in the photo. Visit the John Bridge forum ( http://www.johnbridge.com). Those guys there live and breathe Kerdi.
You need to cut out the drain fitting you have and give it back to the plumber. The Kerdi drain is what you need. It will require that the 2" pipe riser below the floor be cut or extended to just the right height, so plan on opening up the floor, then blocking and reinstalling the plywood.
I see tubing on the floor in your photo... is that radiant heat under the shower floor? Or just a scrap of pipe laying there...
The PEX tube you see is the radiant tube running inside the shower on top of the plywood substrate. I don't see anything we are doing here affects the PEX tube, correct?
I saw on John Bridge a tool to cut the 2" pipe from inside the pipe, which would give me access to connecting Kerdi drain to the ABS below without having to cut the plywood. I would just raise the Kerdi drain to the right height when gluing, then dry pack against the pipe and to the bottom of the flange. Does this sound right to you?
I'm sure you can heat the shower floor but I would be looking for a fairly thick mud bed to cover the tubing adequately. You don't want to weaken the mortar bed and you don't want thermal striping. I would talk to someone who is familiar with this application, which I am not.
You can probably cut the pipe with an inside pipe cutter, but will it be too high or too low. You need to cut off at least enough to remove the existing drain fitting (I am assuming it is glued). Once you've done that there may or may not be enough to glue the Kerdi drain to, at the right height.
edit: I would run the tubing/shower floor question by the folks at johnbridge.com. I am suspecting you want a thicker than normal mortar bed.
Edited 9/23/2007 10:22 pm by davidmeiland
I needed to do a bit of drain redesign to install a mud base and Kerdi -- the saw for cutting from the inside of the pipe was just what the doctor ordered. I got mine at Home Depot for less than $10 IIRC. It was in the plumbing tool area.
The Kerdi drain unit comes with styrofoam spacers to help you set it at the correct height over the subfloor. However, since you have your radiant PEX on top of the subfloor, you should probably use a deeper bed than the spacers are designed for. My GUESS is that you would have to raise the drain by the thickness of your PEX, but someone over at John Bridge should be able to give you a more informed judgment. You should probably get your drain unit before cutting and adding pipe so you can get it properly positioned.
Mike HennessyPittsburgh, PA
As the other boys wrote, you need to cut out the clamping drain assembly.
I had to do the exact same thing, there are a few pictures of the 2-part being cut out and the Kerdi drain installed in this Kerdi thread:
http://forums.taunton.com/tp-breaktime/messages?msg=86714.22
I use a little cutoff wheel that I chuck in a drill. Insert it into the pipe and cut the pipe from the inside. No need to cut the subfloor.
Mongo
A couple of random thoughts:
With the PEX on top of the subfloor, are you planning on adding a slip sheet and diamond mesh between the PEX and the subfloor before doing the deck mud?
I'd at least want a slip sheet, especially with the RFH. I don't use tar paper as a slip sheet when using RFH, the heat can sometimes cause a bit of outgassing from the tar in the felt. I really don't think outgassing would be a factor under deck mud, but if it's a concern for you you can use 6-mil poly.
If using diamond mesh or some other metal reinforcement in the deck mud, isolate the PEX from it so the PEX doesn't abrade on the metal.
Mongo
How thick would you want the mud around the tubing?
Good question.For me, I'd not want the tubing in less than 1-1/2" of mud, and I'd probably throw some sort of wire mesh (not expanded diamond, more like 2" square or larger) just above the tubing, burying the mesh in the middle of the preslope.Kerdi over this will prevent the mesh from ever getting wet and rusting. The Kerdi will also act as a bit of an isolation membrane in case you get hairline cracks in the drypack from the expanding PEX. With the preslope captured on all four sides by walls and/or curb, were any cracks to form, they wouldn't open up.Another option would be to use the bagged mixes that contain reinforcing poly fibers. That would help knit the preslope together to resist cracking.Just an idea...MongoEdit to add: This is a "scratch the head this is what I suppose I'd do" answer, nothing more.Edited 9/24/2007 7:38 pm ET by Mongo
Edited 9/24/2007 7:40 pm ET by Mongo