How to Create a Shower Floor – Part 3

by Roger

Well now we’re ready to waterproof your curb. If you have reached this post before reading the previous two, start with How to build a shower floor from the beginning.  Now that you’re ready to get the curb cut and waterproofed lets get it done.

And yes, I know my pictures suck – I’m a tile guy for cryin’ out loud, not a professional photographer. Until you try to balance a liner, a razor knife, a margin trowel, and a camera while trying to take a photo don’t give me any crap about it. Oh, and you can click on any of the images for a full-size version – partake in the full glory of how much my photography sucks.

We need to start by finding the inside lower corner of your shower pan and making certain that the liner is pressed firmly against it. Then follow it up the corner of the curb and wall to the top inside corner of your curb. This is the spot at which you will start the cut in your liner.

Cutting a liner for a curb when shower walls will be backerboard

Cutting a liner for a curb when shower walls will be backerboard Click to Enlarge

Deciding in which direction to make your cut depends upon how you plan to waterproof the walls. If you are simply using a cementious backerboard on your walls with a moisture barrier behind it you want to cut from that point straight up. Or, more precisely, cut your liner so that when it is placed flat against the studs the cut will go straight up from that point.

If, however, you are using a topical waterproofing membrane (that’s just fancy-ass, pinkie in the air talk for waterproofing that goes right behind the tile) I cut it a bit differently. Start from the inside top corner of the curb and cut straight out to the outside corner of the curb.

Cutting a liner for curb when using a topical membrane

Cutting a liner for curb when using a topical membrane

The reason for this is simple – to me anyway – if you are using a cement backerboard or any type of substrate where moisture will get behind your wall, you want to have as much of a liner at the ends of the curbs as possible to run up the wall. With a topical membrane such as Schluter Kerdi or a liquid such as Redgard you don’t have to worry about that. By the time any water behind the tile gets to the bottom of your waterproofing it should be well below your curb – provided you’ve installed it correctly.

On the inside corner of the curb you should install a ‘dam corner’. These are pre-formed outside corners which are glued to the liner to cover the spot where you’ve made the cut. I do not have a picture of these because I don’t use them, I’m a hypocritical bastard like that. But you should. (Use the dam corners, not be a hypocritical bastard.)

When you do glue your dam corners in you need to make sure you use the correct type of glue. Just like drain pipes – pvc glue for pvc liners and cpe glue for cpe liners. The glue WILL NOT work the other way around. Really, don’t try it, it’s an expensive lesson. Take my word for it.

The liner gets wrapped over the top of the curb

The liner gets wrapped over the top of the curb

Now that you have the ends of the curb cut we need to move on to preparing the curb for tile. Take your 2 x 4 that you used to level your pre-slope perimeter (you did that, right?) and place it in the inside corner of your liner against the curb and the floor. This ensures that the liner lies completely against the floor and the curb without air pockets or empty space beneath it. Then nail the OUTSIDE of your liner to the curb – only the outside, never the inside.

Please note: these photos were taken after my final mud bed was in place. I installed the curb last on this particular project. You can do it before or after your final mud bed is fabricated. Dealer’s choice.

Nailed only on the outside of the curb

Nailed only on the outside of the curb

To hold the liner in place over the top of the curb you need some metal lathe. Provided your curb consists of three 2 x 4’s your lathe needs to be cut into strips sized to fit over your curb from the floor on the outside to the inside bottom corner of your shower. Bend the lathe into a ‘U’ shape (length-wise) and place it over the top of your liner over your curb. Something else I do not have a photo of. Just because I’ve never taken one, not because I do it differently.

You only need to nail the liner on the outside if you have a wooden curb. If your shower is on a concrete subfloor you used bricks for your curb – right? Pay attention, if you fail the quiz later you owe me a beer Pepsi.

I have one more photo for this post and this is it. Isn’t that spectacular? It’s just to show you how I do the ends of the curb when using Kerdi on the walls. “But why don’t you use Kerdi on the floor too?” Glad you asked. It’s a very technical answer and requires you pay attention to every part of it or you may get lost in all the details. Ready? Because some people don’t wanna pay over 100 dollars for a shower drain. Whaddya gonna do?

Shower pan liner on the end of the curb.

Shower pan liner on the end of the curb.

Couple of things I’d like to point out about that last photo before you go bustin’ my chops too hard. First, the excess liner is not yet cut out. I cut it straight down the edge of the drywall there and everything gets tucked straight back into the wall. Secondly, yes, I put a nail through the liner. A foot above the curb. You can light it on fire that high if you choose to do so. (I wouldn’t recommend that, though. And no, I don’t want to talk type about it.)

Now we have to water test your pan to make sure it does not leak. Note: most cities and counties REQUIRE this to be done – don’t skip it. The test simply ensures that all your hard work is indeed correct and your pan does not leak. That’s it.

You need to plug the drain (or you’ll be there all night trying to get enough water into it) which you can do with either a $75 specialty plug, or a water balloon. You pick. You need to make absolutely sure that (and I’m assuming you chose the balloon option) the balloon is pushed far enough down into the drain to block the weep holes as well.  If they are not it will let you know that your weep holes work correctly. Unfortunately it does nothing to reassure you about the liner. If you look carefully into the drain you should be able to see the holes for the weep holes, get below them with your plug.

Then just fill ‘er up. All the way up to just a hair below the top of the curb. (take the 2 x 4 out of it first if it’s still in there) and leave it set for 24 hours. After the 24 hours have elapsed and you are reasonably recovered from your recently induced hangover, check to make sure the level of the water has not gone down. If it hasn’t you are ready to go.

Now if we could just get that elf guy off his ass to write the next post you will learn how to fabricate your final mud bed and tile that sucker. Hang tight, we’ll go get him. Check back real soon, y’all. And as always, if you have any questions at all please feel free to use the comment section below.

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Keith

Hey Roger,

I love your site and your facebook page… your work is inspiring. Though, I’m not sure that’s a good thing, because maybe I shouldn’t be trying to build a shower pan. Alas, here’s where I’m at and I’d appreciate an expert opinion.

I just laid down my PVC membrane. When cutting the liner at the curb, one side came out nice and straight:

[img]http://i.imgur.com/P9WwVD1.jpg[/img]

And this one was, well… not so straight:

[img]http://i.imgur.com/KFfoEZv.jpg[/img]

To make matters worse, when I cut the Xs for the drain bolts, I slipped and went a wee bit too far on one. I put a bit of silicone on it before putting bolting the collar on.

[img]http://i.imgur.com/0gxQcNX.jpg[/img]

Are these ok? Do I start over? Do I call it quits? I am planning on putting the corner dams on both sides (like the “good” photo), but with that bit of 2×4 exposed on the not-so-good side, is it ok, or is that a risk for water getting in there? If so, do i rip it out and start over, or put a small patch on it?

Any expert feedback is extremely appreciated.

Thanks!
Keith

Reply

Roger

Hi Keith,

You should be just fine. Provided the dam corner goes up over the curb and your exposed 2×4 is also above the curb, and your wall barrier overlaps it, you won’t have any problems. You can also glue extra material over the dam corner to cover that exposed wood if need be.

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Stephanie

I’m reading this in a mild state of panic.
My tile guy has over 25 yrs of experience. He helped me convert a huge walk-in closet and microscopic fiberglass shower prison cell into a 6’x7′ luxury curbless shower with 4’x4′ entry and linear drain.. The plumbing for the body sprays and showerheads is a thing of beauty.
Now, the scary part. I haven’t seen him for a month or so, he’s been ‘tied up’.
The liner in my shower is directly on the slab…the flat…flat slab. My top of my linear drain is flush to slab height. How can he possibly mud to the drain still leaving the mud thick enough it won’t crumble? And how is the pebble mosaic going to meet the drain? Thinset+mud+pebble does not equal slab flush drain.
Maybe he’s planning on a Redguard coat over the mud since that was what we agreed for the walls. Won’t that trap moisture between the Redguard and liner?
His liner install matches your description well at walls and studs but I’m just feeling a little queasy at it glued flat on my slab.
I can send pictures…I dread having to peel it off the floor, or having to remove (somehow) my linear drain.
Should I send pics?
.
HELP!

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Jeff Daly

I wish I had read about the balloon before buying that 75 dollar plug…I actually found one cheaper, but still.

Okay, so I have water in my shower now, sitting on top of my kerdi. I did do the kerdi drain and fabric all over. Two questions.

1) I see some darkening in the seam areas. I don’t think it’s enough to get past the 2 inch seam, and maybe that’s the whole point. It doesn’t seem like a true leak. Anything to worry about there? It’s been 24 hours and no significant movement away from the crayon mark. Should I worry about small movements?

2) Since I felt some lumpiness right around the joining of the quarter pieces of kerdi pan, I took some thin set and smoothed it across the top of the kerdi fabric. Seemed like a good way to level it…any problem with it?

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Roger

Hi Jeff,

1. No problem at all. Water will penetrate the seams a bit, but it doesn’t get past the entire seam – ever.
2. No problem with that at all.

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Justin

I ended up boy doing a 2×4 bench. Going with a better bench instead.

So that made laying my liner much easier.

Did the leak test last night at 24 hours my level went down this much http://imgur.com/PkEK5bc

But I just used a balloon to plug drain. Could that account for the level drop?

Evaporation? I do live in new mexico with a dry climate

Thoughts?

And thanks!

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Justin

Forgot to add my only cuts are the drain and sealed with silicon and the curb corners. But water level was a good half inch below the curb

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Roger

I would do it again and make sure the balloon is all the way down into the drain and stack dimes up to the water level. If, after 24 hours, you haven’t lost more than two dimes worth of level then it’s fine.

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Roger

Hi Justin,

Did you get the balloon ALL the way down into the drain? If it didn’t plug the weep holes then that could account for it. As could evaporation in a hot/dry climate.

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Ed

Hi, Roger!
First off, just want to say THANKS for the wealth of sound information on this website. You must really have a profound amount of love for something to spend as much time as you do, not only working with it, but also reading and writing about it for countless hours. Much appreciated!
Okay, enough ass kissing; on to my situation/question:
I have an odd sunken shower, about 35×60″ and 14″ below my slab level in Florida. Being from NYC, I’m not sure if that’s common in the south, but that’s what we have. I’m in the planning stages of renovating the bathroom and am trying to figure out how I’d like to waterproof the shower. The drain is only about 4.5″ away from a tiled wall (wall to drain center), which eliminates usage of a Kerdi drain and shower base. I confirmed with Schluter tech support that their drain flanges are too big for that space, and they actually suggested that I move the drain further out so I could use their stuff (um, nope. if it ain’t broke, I ain’t gonna pay for that).
I believe that a traditional shower pan would be the best way to do the bottom w/ pre-slope, liner, clamping drain, final slope, etc. I pretty much have that in my noggin now thanks to your articles and how-tos. I would however still like to do the walls with cement board and Kerdi membrane over them, because in spite of cement board’s resilient properties when wet, I just can’t get my head around having those things damp in the wall behind the tile all the time… kinda bugs me.
So, traditional shower floor and Kerdi membrane walls– I’d like your confirmation that would work okay (it sounds feasible after a ridiculous amount of research). I’m also unclear on how to properly lap the Kerdi membrane into the sunken shower pan area… I’m assuming most of the 14″ drop is slab cement, so how do I mate the cement board to the actual cement sides of the shower depression? Do I let the Kerdi hang long so it could land inside of the pan’s plastic liner area, or does it have to wrap under the cement board, or something else I haven’t seen yet?
I’m not above purchasing one of your Kerdi shower e-books if you have this particular situation already covered… but if not, maybe a quick diagram of a proper wall cross-section would work, or maybe some stick figures with a non-flaming stick dog will do the trick. Just want to be able to picture it with some confidence before the time comes to rip stuff out of the bathroom.
Thanks again!
Ed :dance:

Reply

Roger

Hi Ed,

Yes, that method works fine (I do not have a manual for that). You would do your complete floor first, running the membrane up the wall to three inches ABOVE the BATHROOM floor – above the sunken portion. Then you would install your backer only down to 1/4″ of the shower floor – you DO NOT want the backer touching the mud. Backer can wick water, so you don’t want that contact where it can wick water up behind your kerdi. When you do your kerdi run it all the way down to the shower floor and run it about two inches out from the walls onto the deck mud.

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Bob

Hi Roger,

I bought your book on doing a Kerdi shower installation and have a few questions about the mortar base:

1. You suggest installing the Kerdi after building the mortar shower base. In fact you show the shower base going in before the substrate is even installed. But in the Schluter youtube video they do Kerdi on the walls before building the mortar base. Does it matter which comes first? Can the mortar base be in contact with bare drywall?

2. For the drain installation, Schluter suggests using a wetter mortar for setting the drain in place. You suggest in your book to use the standard deck mud and bond the drain to the “little mountain of mud” with thinset. What advantage does your method offer?

Thanks in advance!

Bob

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Roger

1. If using kerdi on the walls AND the floor no, it doesn’t matter which order they go in
2. My method gives you a solid base of deck mud beneath the drain, schluter’s gives you a base of thinset which can shrink and crack (not really an issue, more of a pet peeve of mine :D ).

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John

Do you put the topping on the curb over the lathe before or after the topping mix on the floor over the membrane?
And I saw you told someone you can redguard the preslope and then put the pvc membrane over this, is this correct?

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Roger

Hi John,

The curb is the last thing, so yes, after the floor. But it’s not the topping mix – it’s wet mud.

Not sure where I told someone that. You can do it, but there’s no real need to at all.

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kirk

Ok. I’m to the point of cutting the inside top corners of the liner over the curb. I’m doing a cementous backerboard with a moisture barrier. I’m on concrete so I used 2 bricks stacked as my curb. I’m having a bit of an issue with a balled up mess of liner in the corner. I cannot for the life of me figure how it will “lay flat” against the wall with only 1 cut from top inside corner straight out?? I have done that and its still a bunched up mess! Perhaps more Pepsi would be the ticket!! Thanks.

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Roger

Hi Kirk,

Make a cut from the inside bottom of the curb to the top inside of the curb (where you began your first cut). Then fold the liner over the curb and install the dam corners.

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Marcus

Hi Roger,
I am re-doing our shower with help from friends…Unfortunately, everyone has their own opinion. The tile guy tells me that I do not need a liner nor do I need to waterproof the floor mud that is installed, because my base floor is concrete. We have not tiled yet but the Durock underlayment is installed, and it is all the way to the floor, we fiberglass taped and redgaurded the edges really well. We covered the entire durock with red guard, but we did not cover the floor. If you recommend removing the draing and installing a separate liner I will. I can red gaurd the floor also right? what steps do I need to take to ensure this floor is water tight? Oh the curb is made of the same sakrete floor mud we bought at home depot, said it was made for shower floors.
thank you in advance

Reply

Roger

Hi Marcus,

Yes, you need to waterproof your floor. You can redgard it if you want, you’ll need to tie the drain into it using what is call the divot method. Just google ‘shower drain divot method’ and it’ll show you how to do it.

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john

roger,
the pvc rubber liner is to prevent wood subfloor to sip water out of concrete floor ,, that’s been told to me at home depot

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Roger

That membrane is made as a shower liner. It is my guess that it was installed as the floor membrane. Regardless you do not want the redgard on the top of your deck.

Please post follow up replies as a reply to the original question or answer. I can not search through 30,000 comments to figure out what you’re describing (I happened to remember your question). Thanks. :D

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John

roger,
i did put the liner on the floor as a form to hold the concrete in place for my shower floor i am not gonna apply regard on top of it can i put kerdi membrane instead since the concrete isn’t waterproof…thanks

Reply

Roger

Yes.

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john

hey,,, roger ,,can i put kerdi on top of concrete shower floor with pvc liner underneath the sub wood floor…thanks

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Roger

Hi John,

Not sure what you have going on there. Why is there a pvc liner beneath a wood floor?

Reply

Steve Baker

Thanks for a really informative tutorial, I know you have helped many people get it right. I encountered a problem in Part 3 that your readers may find helpful. I water tested as you explain and all is well (10 cent balloon is brilliant!). I also decided to test my weep holes and they failed. What had happened was the silicon oozed all the way in to the upper flange when I tightened it down and this blocked all weep holes. Solution was simple, I removed the upper flange and cleaned all silicon off of it. I also cleaned off excess silicone at the lower flange being careful to not disturb the seal made between liner and lower flange. Now weep holes work well.

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Roger

Thanks Steve! :D

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Pete

Hi Roger, Great site. Thanks for all your expertise. I drywalled my Bathroom with greenboard before I found your site. I built my shower end wall and curb with steel studs. Do I need to remove the greenboard and expose the studs, or can I build a traditional shower pan up the walls, put in a vapor barrier and cover with hardiebacker? Also, can I chisel our the greenboard for the pan liner without compromising the vapor barrier as long as I overlap vapor barrier onto the pan liner? Do I need to run a bead of silicone where the poly overlaps? Is there supposed to be a gap between the Hardibacker on the walls and the Finished Shower pan?

Thanks in advance for your answer, Pete

Reply

Roger

Hi Pete,

Yes, you need to remove the greenboard and replace it with backer. Overlap the barrier into the pan liner. No silicone at that gap, just leave it open from the wall to the floor. If using a vapor barrier yes, there needs to be at least 1/8″ between the bottom of the backer and the floor.

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David

I’m a little confused on the brick curb.

The liner goes over the brick curb just like if you had a wood curb, correct? Then I somehow attach the liner to the front side of the bricks? And then I still use the lathe mesh over the liner, cover with thinset, and then tile?

Can you give a little more detail on the curb build when using bricks?

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David

Never mind, I found this on your site. Problem solved.

http://floorelf.com/creating-a-threshold-or-curb-for-your-shower

Reply

Roger

Okay, good. :D

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Roger

Hi David,

Yes, it goes over the bricks just like the wood. You do not attach it to the front of the bricks, the lath is the only thing that holds it in place. After that you use wet mud (1 part masonry lime, 1 part cement, 4-6 parts sand) over the lath to form your curb. Tile is bonded directly to that once it cures.

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Brian Eull

Hi Roger,

I noticed you told David in the above post to use 1 part masonry lime, 1 part cement and 4-6 parts sand for the curb, I am assuming(yes I know what that makes of you and me!) the pre-slope and final slope mixture would be to dry to work with when applying to the curb?

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Roger

Hi Brian,

Too dry and it isn’t sticky at all. Almost impossible to form on vertical surfaces without the sticky. :D

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Stephanie Maps

Custom Building Products aka redgard tech support 800-272-8786 says “nothing” will bond/seal between redgard and polypropylene liner.

They recommend either furring the concrete wall, installing backerboard putting the polypropylene liner behind the backboard doing away with the need for redgard entirely.

OR

Painting Redgard on to the concrete wall, on the outer surface of the backboards and onto the surface of the preslope. Requiring much more redgard but doing away with the need for the polypropylene liner entirely.

I don’t want to lose the inches in the shower to fur it and i am not eager to use/trust ONLY redgard as a pan liner.

(sigh)

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Roger

Redgard works just fine as a pan liner. When done correctly it works just as well as any other. Really. :D

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Freiheit

Are the dam corners made of different materials? In other words if I have a CPE liner do I need CPE corners?

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Roger

Hi Freiheit,

Yes, you need to get the same material your liner is made of.

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Stephanie Maps

Thank you SO much for this site Roger. Tis’ truly awesome!

i know how to handle a wood stud wall.. i know how to handle concrete wall but what should i do since i have BOTH?

I’ve got a brick curb on a concrete floor with wood studs with the fancy notch cut out on on two shower walls and a solid concrete wall on the third shower wall. I’m ready to create a pre-slope but have realized i don’t really know exactly how i’m going to handle the waterproofing/sealing where polypropylene shower floor liner meets the Redi-gard on the concrete wall.

Meaning – if the polypropylene liners lays on top of the pre-slope and 6 inches up the studs in those notches that works great if ALL my walls are wood studs. But since one of my walls are concrete i was going to Redi-gard that entire wall.

So i am thinking after pre-slope. FIRST Redi-gard the entire concrete wall from the top of the shower all the way down until i am maybe 4 inches above the pre-slope. THEN lay down the polypropylene liner in floor and 6 inches up the walls. The liner will lay inside the notches of the studs but on top of the last 2 inches of Redi-gard on the concrete wall. How do i – should i seal the polypropylene liner to the Redi-gard there?

Or am i COMPLETELY off base with my entire approach? Am i going to create a bulge in the tile near the bottom of the concrete wall if i attempt this?

Maybe i should do away with the polypropylene liner entirely and JUST do 3 coats of the Redi-gard on the entire concrete wall, 6inches up the wood studs and the entire final mud shower floor (before tile).

i dunno. i’m largely clues-less but thanks to your site am slowly getting there.
What would the floor elf do?

thank you muchly,
Stephanie

Reply

Roger

Hi Stephanie,

I assume you mean redgard, not redi-guard. You have two options:

1. You can frame out a small wall in front of the concrete wall and build as a regular traditonally lined floor with the liner behind the backer.

2. You can use a topical membrane (redgard does work) as the waterproofing on your floor and walls.

You can not make a transition from a traditionally waterproofed shower floor to a topically waterproofed concrete wall.

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