Schluter Drain Plumbing Connection [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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07-27-2019, 08:15 PM
Doing a schluter shower kit 38 x 60 - I did not follow instructions and have already thinset the shower board down and now need to do the drain. I have no access to plumbing from below. We precut the plumbing to fit the drain but now when I dry fit it I notice there is a bit of a gap between the drain end block (don't know what it's called) and the plumbing when I seat it fully down on the shower pan.

Will this be an issue if I glue down the drain and there is a gap between between those two parts, there is still about 1/2 or more overalp between the drain and plumbing.

Hopefully what I'm asking makes sense. I can take a few pictures if it helps.

Thanks for the help.

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07-27-2019, 08:51 PM
Not sure I follow your description. The drain should slide about an inch into the drain pipe. Are you saying it's only sliding in about 1/2 in? Or is the drain standing proud of the foam tray?

07-28-2019, 08:08 AM
Yes it's not sliding in fully, probabbly it could go another 1/4 inch, when I seat it on the tray and look inside the drain, there is a bit of a gap.

07-28-2019, 08:15 AM
Welcome, I. :)

is your drain riser well supported and not perhaps being forced down a bit when you try to dry-seat your drain?

A half-inch of contact between pipe and drain collar is a bit shy of what I'd like to see as a minimum, but you may find that you get more contact than that when you actually install the drain with the appropriate cement on pipe and collar. Three-quarters of an inch of contact would fit my comfort level quite adequately.

Problem with that hypothesis is that you don't really get to do "overs" once you've glued the drain onto the riser.

My opinion; worth price charged.

07-28-2019, 11:56 AM
Dry-fitting PVC is always problematic as you often can't fully insert it due to tight tolerances. When glue is applied, this acts briefly as a lubricant to achieve the full insertion depth. Your best bet would be to measure the distance from flange to tray when the drain is sitting atop the riser pipe. If this distance is about between 1 in and 3/4 in, you should be ok for final installation.

The last thing you want to do, though, is to glue it in place just to discover that it isn't positioned properly.

Oops. Just reread your answer. Seems like you don't have enough riser length? If so, can you cut the riser sufficiently low and glue on an extension? They make inside pipe cutters for PVC plumbing if you have no access from below..

07-28-2019, 02:27 PM
WHen I did my last one, I had to put a block underneath the p-trap so that when I pushed down on the drain assembly, it didn't flex, allowing me to seat the drain onto the riser. The trap arm was about 4' (max allowed in most codes is 5), and it wasn't easy to support otherwise, so was just flopping around.

You may be able to try to loop a string around the pipe to help hold it long enough for the cement to bond the flange in place. Note, the cement literally melts the surface of the hub and pipe, which is why it fits easier with the cement versus trying to dry fit things. Once the solvent evaporates, it is literally welded together. I'd want to hold things manually for a couple of minutes to let that happen enough so that it didn't slip apart. Once that was stable, you could pull the string out, slater thinset underneath the drain (you should be able to pull it up at least a little to allow that), then set it in place.

07-28-2019, 04:27 PM
The riser is fixed and not moving when I dry fit. Is 3/4 insertion of riser into the drain collar sufficient, I think I have that at least. It's just that it's not fully flush against the drain collar so there is a bit of a gap when I feel through the drain. I did dry fit it so I guess it could go slightly lower when using cement.

I would prefer not trying to recut, no access from below and 4" around the drain is all i got to work with up top.

07-29-2019, 12:04 PM
You don't necessarily need the top of the riser and the collar to butt against each other, 3/4" close is good enough. You could try sanding the top of the riser or ID of the collar a bit, just do so uniformly. You will, however, want to sand smooth the top cut edge of the riser so as to discourage hair from catching and hanging on a ragged edge.

07-29-2019, 02:23 PM
Thanks for the tip Dan! I did not think of the hair issue, will definitely smooth out the riser cut.

08-21-2019, 11:26 AM
Hi all,

Wanted to get some thoughts on what to do. First time doing a shower - used schluter kerdi shower kit, finished wall and drain and all looks good. I had a question on the ceiling. The ceiling uses a 1/2" mold resistant drywall. What are my options here for finishing?

1) Can I just finish the ceiling like a normal ceiling with proper paint that's used in bathrooms?
2) Should I put schluter membrane on the ceiling and then paint?
3) If I do tile, can I just tile on top of it or should I do schulter membrane first?

The ceiling height is about 7ft, it's a basement bathroom. The joist span is 16 oc, I've read some places that for tile it should be 12" but not sure.

Thanks for the help,

08-21-2019, 11:58 AM
I've combined your question with your previous thread, Ivan, so folks can see what you're working on and what's been previously asked and answered. A moderator can give it a more generic title any time you'd like to suggest one.

MR Board is a poor choice for ceilings (or any other application as far as I'm concerned) and for 1/2" MR Board the requirement is 12" joist spacing for ceiling applications. You can use 5/8ths" MR Board over 16" ceiling joist spacing.

I would not recommend you tile over what you've got. If you're willing to replace the ceiling, I'd recommend you change to 5/8ths" drywall or a suitable CBU that's recommended for ceilings at your 16" spacing.

My opinion; worth price charged.

08-21-2019, 12:15 PM
Thanks for combining the threads and your response on my question.

Why is MR board a poor choice for ceilings, I would like to know for future reference.

Sounds like I need to change the ceiling to 5/8ths.

I do have regular drywall that's 5/8ths, can I use that? Or do I need to use CBU if I want to tile the ceiling in shower?

08-21-2019, 03:21 PM
MR Board tends to sag between joists in ceiling applications, 'specially if there is insulation above. That is why the manufacturers call for closer joist spacing in that application.

While 7 feet is getting to the low side of acceptable for a shower ceiling, but I have tiled such ceilings over 5/8ths" drywall, which I use for all ceilings regardless the joist spacing.

That falls under the same heading as the advice you receive from your investment broker that past performance is not necessarily indicative of future results.

My opinion; worth price charged.