Hello,
I hopefully have a quick question. For those keeping tabs, I’m still building my house – getting close though. My plumber installed the shower pan liner for my shower which is 4 x 4.5 ft x 7 ft tall. It is on a second storey and will be a steam system. We are going to use cement board and Kerdi (installed by a “certified Kerdi installer”). That’s the background.
After looking at the pan liner, my tile setter noticed the drain moved a little bit, so he decided to check it out and it the drain can move up about 1.5 inches which seemed odd to both of us. When I called the plumber and asked him about this he replied “this is how I always do a second floor drain / shower pan liner – once the “dry pack” is in to slope the shower floor, that will hold the drain in place”. To me this didn’t make sense, but I’m not a plumber or tile setter, therefore here I am.
Question – does this make sense? I would assume that the drain should be at least siliconed in place or something so it doesn’t move around. Would this not eventually crack the grout / tiles around the drain since it’s basically “floating” there? Also, the pan liner didn’t wrap completely around shower curb (it’s only barely above the start of the curb – say around 1″ in on top of the curb). Again – this seems to be an issue to me, but I’m not a pro at this. Shouldn’t the plan liner at least cover the entire curb to prevent potential water from running behind the liner?
Any thoughts would be great (and also how to tell the plumber who does this for a living that he did it wrong if in fact the above installation technique poses a problem).
As always, thanks for your help and your time / expertise.
Replies
In a Kerdi shower the drain should be installed with the pre-slope mortar, and it should stick pretty well to that mortar. I suppose if you pry on it you could lift it but it should not be easy. Getting the mortar fully packed under the drain, and getting those holes in the drain engaged with the mortar... both very important. The Kerdi is then installed over the drain fitting and is thinset to it, and once that's done the drain should be rigid. The trap should be directly below the drain fitting and it sounds like your trap arm is 2 feet long or maybe slightly longer based on the dimensions you gave. If you have access underneath the floor you could install some pipe straps on the trap arm and really stiffen things up.
Rereading your post above it sounds like maybe the plumber installed the drain but the mortar is not in place. In that case the ability to lift the drain will be useful. Just make sure the pipe is strapped below after the mortar and Kerdi are in place. When I have done Kerdi drains I do the mortar bed first and set the drain in it. Then I set a 5-gallon bucket of water on the drain so the plumber can shove the pipe in from below. You may be going about it the other way.
To clarify - there is nothing else installed but the drain and all the normal rough-ins and drywall is up. I'm basically ready to put up cement board in the shower, but I wanted to make sure the pan liner / drain is installed right. My main concern was that currently the drain can very easily move up about 1.5". Will this still be an issue after I pre-slope the mortar, do the Kerdi, etc.? Should I make the plumber somehow glue the drain to the subfloor so it won't move, or is it ok or industry practice to do what my plumber did? Thanks again.
Just by chance I happen to be in Anaheim, CA right now attending a Kerdi
workshop put on by Schulter we are finishing tomorrow. There is no certification. It is just a very informative 2-1/2 days of classroom and hands on. If the plumber is using a Kerdi drain and you have 1-1/2 inch play to lift it up you the hole was cut using their template you should have no problem. The mortar bed and the locking keys will hold it in place. I have installed about 12-15 of these showers and love them.Feel free to e-mail me with questions..Frank
Sorry I just reread your post. When using the kerdi system you do not use a pan liner nor do you do a preslope. Your slope is set when you set your mud bed. And install the Kerdi drain all at the same time.Go to schluter's website and watch the installation video for a mud pan installation.This should answer your questions. You "Certified installer" should know
this.Frank
You need to get mortar under the drain flange so that it is fully supported. The fact that it can be lifted is to your advantage. If he glues it down you will not be able to complete the install correctly. You do have the Kerdi drain, right? You can't use Kerdi without it.
If you don't have it, the Kerdi Shower e-book from johnbridge.com is worth the $10 price.
I don't have the Kerdi drain. I will be using Kerdi on the walls / ceiling. Does this change your suggested installation technique of applying the mortar underneath the drain flange, or should I do that anyways?
It doesn't make sense to me to combine the two systems, but if you're doing that, the drain should be installed first, then the preslope, then the membrane, then the second layer of mortar. If your tilesetter or plumber has already installed the membrane but there is no preslope underneath it then that person needs to be fired because they don't know what they are doing. Who is the mastermind on this job anyway?
To answer your last question first - the "mastermind" would I guess be me since I am contracting out the build of my house. I rely on recommended and "checked-out" professionals to know what they are doing, but I am learing quickly (or maybe not quick enough), that that usually isn't the case.
The drain was installed prior to the drywall stage. After the drywall stage, he installed the pan liner only. Next my tile guy is going to put up the cement board, then do the pre-slope with dry-pack. After that, he will install the Kerdi, then he will thinset over top of this and tile.
I just wanted to make sure that if this is the process we are going to do, I won't have any issues in the future b/c the drain right now isn't "fastened" to the subfloor, therefore it can easily be moved up about 1.5".
Thanks again for everyone's help and any other recommendations.
If your shower pan liner is not on top of the preslope, i.e. it is sitting flat on the floor, you have a big problem. What is under that liner?
I'm not sure if we're to the bottom of this yet.
If you are not using kerdi on the floor, then the liner is in the wrong place. It needs to be on top of the preslope, then a dry pack bed is placed on top of the liner. Nothing but trouble if the liner lays on the flat floor.
However, if your tile guy is going to use kerdi on the floor, you don't even need the liner. The kerdi goes on top of the sloped dry pack, but with this system, you must have the kerdi drain.
What does your tile guy say?
OK- hopefully we're at the end of this. My tile guy says he would prefer to install everything only after the drain is "fixed" and tight to the subfloor. He is concerned about cracked tiles / grout.
For some background, we have a laundry on the second floor also and that drain is tight to the subfloor (prior to the application of a shower pan liner). What I'm thinking happened is that when the plumber was away for a couple weeks and we drywalled, he forgot to "fasten" the drain similar to what he did in the laundry. Now he's telling me it's ok, which of course I want to make sure it it.
The plan is to put Kerdi on top of the drypack. Here's is what a cross-section would look like:
flat subfloor (3/4" Advantech)
shower pan liner / drain
Drypack for the pre-slope
Thinset to attach the Kerdi
Kerdi
Thinset for tile
Tile
I hope this clarifys everything. Thanks again for everyone's time in looking at the post and helping me out.
Where you are confused is that you are trying to use 2 different systems at the same time.
Kerdi needs a Kerdi drain, a regular drain that clamps onto a liner will not interface with the Kerdi. The way you are planning will just end up trapping water in the drypack between the liner and the Kerdi.
If your installed liner is sloped to the installed drain there is no need to kerdi the floor. If the liner is not sloped , I would rip it out, get a Kerdi drain , which comes with a dvd that shows how to do it their way.
I believe that you are confusing the terminology.............preslope is just that; pre-
It goes UNDER a vinyl liner on top of which is installed a DRY PACK SLOPED MUD BED.
There is absolutely no reason to pre-slope or vinyl liner when using Kerdi. In fact I would think it would not be a good thing at all.
And........a vinyl liner always wraps around the curb.
Pull up the liner and cut upen the sub floor. Get you drain secured and start putting things back to gether the way they should be now while you don't have a lot of money thrown away yet.[email protected]
Don't confuse the man. There IS a need for preslope with Kerdi.
There is?
I've not done one. Preslope to where? The top of the mud bed is sealed off, why and where would pre-slope go?
The videos show the pan being set in place then the membrane on top of that. No pre-slope anywhere.[email protected]
Go to the Schluter site, David. Find the link for the video of the Kerdi drain.
Watch the video.
Come back and tell us, please, what you meant when you said, "Don't confuse the man. There IS a need for preslope with Kerdi."
Your statement sure confused me, and I have had well-qualified tilesetters install Kerdi shower systems.
What I have learned in researching shower pan construction, is that preslope is the term given the shape of the first part of a drypack mudbed install, in which the mud is laid into wire lath on the floor, packed up to the level of the subdrain flange of the clamp-ring drain fitting, and finished with outer edges sloping smoothly to the drain.
It is on this surface, then, that the CPVC (or other suitable membrane material) is installed and fit well to the drain's clamp ring. After the membrane installation, another layer of mud is done up to the surface upon which the tile will be laid.
A Kerdi drain is installed without a "preslope" step. You'll see in the video.
The drain has no clamp ring. The Kerdi membrane is laid directly onto the sloped drypack mortar, in which the Kerdi drain has been set flush. The membrane is glued directly to the large flange of the Kerdi drain.
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"A stripe is just as real as a goddamn flower."
Gene Davis 1920-1985
Gene.... have you installed a Kerdi shower? Did you install the Kerdi flat on the subfloor?? Or, did you install a mud preslope or perhaps use the Kerdi shower base?
I've subbed my tilesetting, David, including the Kerdi work.
Schluter's USA HQ is right up the road from us here, and no one here doing any kind of tile work uses anything but Schluter stuff for tile jobs.
We've Schluter suits, engineers, and warehouse and office workers living amongst us.
I have certainly watched, and done so closely, when a Kerdi drain is installed with its surround of sloped mudpack, then membraned with Kerdi when the mud has set.
I haven't done it myself, but it looks relatively straightforward. Screed sticks are the secret to success.
That said, a shower job is quoted here including all the Kerdi stuff. We just give them a drywalled "room" with a hole in the floor in the right place, and a section of PVC drain line poking up through the hole a little. The PVC is not cemented into the fitting below, so that the tile guy can cut it to the right length for the Kerdi drain, then cement everything together.
Watch the video.
Actually, watching it is an option for you, but it oughta be a requirement for the OP's "qualified installer."
This thread is amazingly long for such a simple topic. I usually suggest to any OP wanting to know about a Kerdi shower, to go and discuss it amongst the pros at the John Bridge forum.
The misinformation here comes from those that are not hands-on familiar with a Kerdi shower system.
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"A stripe is just as real as a goddamn flower."
Gene Davis 1920-1985
Gene, you've told us many times how Schluter is right up the road. Whatever. A Kerdi shower floor is installed over some type of preslope. You can use mortar (I do, I have). You can use the Schluter preformed pans if you shower is of a matching size. You could possibly use some other type of manufactured preslope product although I am not familiar with those.
Anyway, it sounds like the OP's tilesetter has laid the membrane he is using flat on the floor.... no preslope. The OP has been given a fair amount of good info here on what should be done, but he seems mostly interested in the loose drain issue, which could also be an issue but seems secondary to me.
David, I restated the bit about our over-soaked Schluter culture here to make a point. For everyone here doing tile, Schluter products are used almost exclusively, and the tile mechanics are all well-trained.
Good on you, for personally doing a mud bed! In my youthful days that sort of stuff was cool, but today, I prefer to handle things like money and sportsgear. Mud? Yuk!
Having been to some training so I could know how to view things, I never heard the word "preslope" used by Schluter in defining the specifics of shower system installation.
I have their written installation manual, and it is not mentioned in there, either.
"Preslope" is used, however, by outfits like Laticrete, in installation instructions for the types of membrane installations that go into a shower drain with a clamping flange and perimeter weep holes above the flange.
The "pre" part of the word is meant to convey the fact that the mudwork for the shower pan is a two-step function, the base first going down with its surface sloped to the drain clamp ring, with the membrane then going atop it.
Per Laticrete's installation instructions (and Michael Byrne's, in his excellent book, "Setting Tile") the pan, thus membraned, is further built up with a second layer of wire-reinforced mortar. It is that second layer that the tile goes onto with its own mortar, then grout.
With the sloping membraned pan incorporated into the shower floor, the second drypack mortar layer is often not pitched as much as the preslope surface.
But, hey, you know all this. Except for maybe the antics with semantics. What is the meaning of "pre?" What is the meaning of "is?"
I know you live on an island, but is the language there that provincial?
So, I'm being overtly pedantic with you here, but it's in response to the dismissive tone in your post, something about my Schluter banter and the fact that I am hands-off with the mud thing.
As you say, "whatever." Even folks my age know the tone with which that word is delivered.
And, how about this? If Breaktime filtered out posts from all but professionals, we could not even be having this conversation. Wow!
Touche. Or, more appropriately, as I know you'll reply, en garde!
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"A stripe is just as real as a goddamn flower."
Gene Davis 1920-1985
Call it whatever you want.... you need your membrane tilted towards the drain.
David,
You are misunderstanding the terminology, or perhaps it is another one of theose regional differences.
Lets leave Kerdi out of this for now.
Pre-slope goes on the underlayment or subfloor BENEATH the vinyl membrane or liner. The purpose of this pre-slope is to direct any water that may have found it's way through the MUD BED into the weep holes of the drain. We do not want standing water in the liner beneathe the MUD BED. The preslope will pitch the liner towards the drains weep holes.
On TOP of the liner one builds a sloped (again) MUD BED or DRY PACK MORTAR BASE being sure to place small pea size aggregate around the weep holes as to not clog them with this mortar. This MUD BED also is pitched towards the drain, 1/4" per foot or so.
On top of this MUD BED one intsalls and grout his tile floor flush witht he top of the strainer which is attatched to the drain.
NOW, if you desire, you CAN install Kerdi on top of the mud bed and then up the walls as well if so desired. But as others have explined, it seems that one cannot use the Kerdi drain if you do a MUD BED, only of you install the Kerdi ove their proprietary base.
Lets see if that works. Go to the site and see for your self.
Eric
[email protected]
>>it seems that one cannot use the Kerdi drain if you do a MUD BED, only of you install the Kerdi ove their proprietary base.
Completely wrong. You can install a mortar PRESLOPE over the subfloor in conjunction with the Kerdi drain, then install the Kerdi, thinset, and tile.
You can also buy the Kerdi foam shower base, but last I checked it only came in two sizes. If you use that base it is a substitute for the mortar. I assume that the majority of Kerdi showers are NOT done using their foam base, but are done using mortar, since the sizes are so limited.
Completely wrong. You can install a mortar PRESLOPE over the subfloor in conjunction with the Kerdi drain, then install the Kerdi, thinset, and tile.
Thanks david. That is interesting and I'm not sure I was very aware of that even though it rings a bell in the back of my head.
It would seem then, that if what you are stateing is factual, then there would be no reason that you could not use the Kerdi drain over a mud bed?
I always thought that the base sizes were rather limiting.[email protected]
IMO you can most easily use the Kerdi drain over a mortar bed (I wanna call it PRESLOPE!). A year ago when I last did a Kerdi shower floor they were selling a 32x60 and a 48x48 size in their foam shower trays. I assume they will realize they are losing market share and will come out with more sizes. It takes me about 2 hours to put down a mortar preslope in a 3x4 or 3x5 area with a simple slope to a center drain, so I couldn't save much buying their trays, especially if their cost is similar to the rest of the Kerdi goods (they are fairly expensive).
There are no weep holes in a Kerdi drain. The membrane goes over the top of the flange. and no water is below it.
There are a couple of companies out there that will soon be offering custom sized trays. If they can garner or better yet, corner the demand it may be worth their while to go custom.[email protected]
I'm worried about your choice of a tile installer if this is the system he/she uses. As I and several others have stated, any liner must be installed on top of a preslope and NOT on a flat floor.
Again, if you are to use kerdi, the liner is not needed, and the drain used for the liner system is the wrong one for the kerdi. There is no way to make these systems work with each other.
I would prefer the drain to be stable, but at this point I am more worried about the rest of the detailing of your shower pan installation if your installer is unaware that you don't mix the two systems. To me, it means he/she may not know how to do either system correctly.
Open the floor or the drywall, fasten the drain (the correct one for whichever system you decide to go with), get yourself an installer that knows the difference between kerdi and liners.
NO NO NO How many times do you need to hear it? NO.......If your tile expert is endorsing this x-section, then ditch him. He doesn't know jack.Use Kerdi only on the floor...... it goes with the walls really sweet. Tear out the liner that's there. Install drywall right down to the subfloor. Put in a sloping mud bed. Install a Kerdi drain. Install Kerdi on floor, walls, ceiling, curb, and the dog if he gets in the way. Use thinset to set the tile. Do not use so called premixed thinset... that's not thinset at all. Having the ability to move the drain pipe a few inches is great. Then your tile guy can put it where the tile pattern wants it. The grate on the Kerde drain is square and that looks really nice with square tile. Go to http://www.johnbridge.com and read the forum. They know a lot about this.
I am not familiar with the kerdi system but I can tell you that if your vinyl liner is in on the subfloor and not pitched towards the drain with either a foam preslope system or a packed mortar bed (gage is i believe the terminology) then you are asking for trouble.
The IRC code requires a sloped liner for a reason. (and code is the minimum)
I have the floor gaged (sloped) after the drain is screwed to the subfloor, then put in the vinyl pan, then coat the vinyl pan with one of the liquid vinyl coatings then put the wet bed floor in.
Search FHB for articles on tile showers. There have been some good articles written over the years.
Sounds like you are doing a convetional pan and drain, the you plan on putting Kerdi on the walls,am I correct? If that is what you are doing then the drain moving is not an issue, the mud will hold it down, but I would definitly get the curb completly covered.
If you are doing the entire Kerdi system then remove the drain and liner as they are just in the way, and the kerdi installer should set the drain.
I am certainly no expert on showers.
It sounds like you are combining systems (Kerdi with Conventional)
Might want to check out he Kerdi website install videos.
Regarding the membrane being down before the PREslope. I've seen it done like that (conventional system, no Kerdi involved)but it seems to me that the slope should be down first then the membrane so that the membrane can drain.
I lent my Michael Byrne book to an acquaintance 6 months ago and haven't seen him or the book since or I would look it up. May replace it with a John Bridge offering.
My question is PREslope, before or after membrane?
Preslope, membrane, mud bed.
ThanksTFB (Bill)
you bet.