Preparing a Shower Wall for Tile

by Roger

If you need to decide which method is best for you I have a free shower waterproofing manual that you can download here. Shower waterproofing manual. Go get it – it’s free! And I’m not gonna use one of those damn annoying pop-ups! I hate those things…

There are several ways to prepare the wall of a shower for tile. Depending upon what was originally there, what stage the shower rebuild is currently in, and what type of tile you plan to install plays a minor part in choosing which method to use.

The most critical aspects of which product to choose are: how much work you’re willing to put in and how much money you’re willing to spend. The end result should be the same – a waterproof box. The methods used to accomplish that vary in effectiveness and cost. So we’ll start with what I consider the most bullet-proof method.

Kerdi Shower System

A company called Schluter makes a shower system called Kerdi. The entire system, which can include everything from the wall membrane down to the entire shower base, is considered by many professionals to currently be the top of the line in shower substrates and waterproofing membranes. And no, I don’t work for them. I don’t owe them money. And they don’t take me on those all expense paid vacations to Bermuda – bastards. I like their products anyway.

The waterproof membrane made by Schluter is called . . . well, Kerdi. It’s bright orange and you can see it from space. It is installed over regular drywall or cement backerboard with regular thinset. It makes your shower a big bright orange waterproof box that glows in the dark. Okay, it doesn’t glow in the dark.

The material is difficult to describe with words, it’s kind of like a fleece-lined rubber(ish) membrane. I like it for two reasons: It is the best available and it happens to be the easiest, least work intensive option (once you are used to working with it). While there is a fairly large learning curve to effectively work with it, Kerdi is fairly easy and very well documented. There is a wealth of infomation on the internet about it. Just Google Kerdi. Go ahead, I dare ya. Noble company also makes a similar membrane called NobleSeal, but it isn’t pretty bright orange.

Liquid Membranes

After Kerdi, a brush or roller applied liquid membrane such as RedGard works very well. It is applied with a brush or roller like a thick paint. It’s bright pink. You coat it once, after it changes to red, coat it again. Usually two coats is sufficient for any shower (except steam showers). After is sets overnight just go in and stick the tile to the membrane itself. It is a bit expensive, but they are also simple and quick to install.

There are several of these membranes on the market, the most common being Redgard. My favorite is Laticrete Hydroban. Laticrete also makes Hydrobarrier and Mapei has Aquadefense. They are all pretty much comparable.

Preparing shower walls with RedGard

If you are building a shower and want a manual describing the entire process you can find it here: Liquid waterproofing membranes for shower floors and walls

Cement or Fiber Based Backerboard

If you don’t want to spend the money for Kerdi or RedGard, this is your next best option. These are products such as Durock, Hardiebacker, and Fiberboard. While the product itself is not waterproof, it is water-resistant. The backerboard will actually hold water, as in water will soak through it. There needs to be a vapor barrier put up between the wall studs and the backerboard.

The unique thing about these products is that, although they are not waterproof, they will not become unstable with moisture. (That just means water doesn’t make it swell up.) To use these you must first install some type of moisture barrier over the wall framing. Get a 4 mil or thicker plastic (mil is just the thickness of the plastic) which can be purchased at places like Home Depot, and staple it to the studs of the wall framing. You can also adhere it to the studs using silicone. Completely cover all areas from the tub to the ceiling. The backerboard is then screwed onto the studs to make your shower walls. Then you just stick the tiles to the wall and shower away.

How to install backerboards

I also have a couple of manuals describing the entire process from the wall studs all the way up to a completely waterproofed shower substrate ready for tile. You can find them here:

Waterproof shower floor and walls manual

If you have a tub or pre-formed shower base and need to only do the walls you need this manual:

Waterproof tub and shower walls

Denshield

Denshield (and others like it) are similar to drywall in that they are lightweight and easy to install.  It is a waterproof core laminated on each side with a fiberglass based face. It is installed like drywall except you need to run a bead of silicone between the sheets to waterproof the seams. You then need to use fiberglass mesh tape over the seams. It does not require a moisture or vapor barrier behind the sheets. When properly installed Denshield is an adequate tile substrate for shower walls and relatively affordable compared to alternative methods.

If you are building a shower and want to use a topically-faced wall substrate you can find that manual here: Building a shower with a traditional floor and topically-faced wall substrates

If you are just tiling around a tub or pre-formed shower pan you can find that manual here: Topically-faced wall substrates for tubs and shower walls

Plain Drywall *DO NOT DO THIS!!!

Yes, you can do it if you must. I absolutely do not recommend this! But I’m also realistic enough to know that if you decide this is what you’re going to do, I’m not gonna be able to stop you from here. You can not just go up to your drywall and start sticking tile to it – ever. There needs to be a moisture barrier between the drywall and the framing. At least then when water gets behind your tile and grout and disintegrates the drywall it won’t disintegrate your wall framing as well. Remember, if water gets to one of the studs not only will you be replacing the shower, you will need to do some serious repair work to your wall framing and possible structural work. Please also note that using this method runs the risk of parts of your wall literally falling apart if it gets wet – drywall disintegrates in water.

And it will. So don’t do this!

Unsuitable substrates for shower walls – no matter what you’ve been told

  • GreenBoard, also known as green drywall. Never use this or you’ll get a lot of practice replacing showers.
  • Backerboard without a moisture barrier.
  • Drywall without a moisture barrier. (I do not recommend drywall as your substrate at all.)
  • Any type of plain wood or plywood. Ever. No, painting it makes no difference.

I’m certain there are a lot of things I’m not thinking of that someone else will. If you wouldn’t let it set in a swimming pool for a week, don’t use it for your shower walls. That should clear it up.

The golden rule

Although there are many products that can be used for your shower wall, many should not be. Regardless of which method you choose one thing to keep in mind is that you need to have some type of waterproof membrane between your tile and your wall framing. Kerdi membranes and RedGard are both waterproof membranes that go directly on the wall. Plastic stapled to the frame before installing your substrate is also acceptable.

The main thing you need to ensure is that no water reach your wall studs – ever. Wood swells with moisture and the only place that excess swelling is going to go is right into the back of your tile. Remember, your tile is not waterproof so you want to adhere your tile to a substrate that is as waterproof as you can make it.

If you need to decide which method is best for you I have a free shower waterproofing manual that you can download here. Shower waterproofing manual. Go get it – it’s free!

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joe

You may have already answered this question but I want to make sure I do this 1time. I have installed a 32″ per formed shower unit in my bathroom. Above the shower is a 22″ space covered with “green” sheetrock. I was told I could use that because it would not get direct water on it. #1Were they correct #2 can I make it work or should I tear it out and start over. I wish I saw this site first. Also I don’t know if it will make a difference but the tile I am using is 12″x24″ so there will be minimal grout lines thanks

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Steve Booth

Love the site! Just bought the e-book on liquid waterproofing. Very helpful! That said I had already done the traditional shower floor (following your instructions) with the PVC barrier. I will be using hydro barrier per your instructions (had already bought before reading you like hydro ban better but all good!). So question is – is it worth me putting the hydro barrier on the finished shower pan before tiling or is that overkill at this point?

Love the site!!!

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David

Hi Roger,
I purchased your liquid topical shower waterproofing guide and it has been very helpful. I have the backerboard up on the walls and I am about to start laying the mud bed. I have a few questions. 1) The drain pipe on my shower is almost flush with the sub-floor so when I fit the kerdi drain on the pipe it sits way too high. When I look inside the drain the water level is about 5 or so inches down. It seems like I could just cut the pipe down a bit so the drain fits, is this ok? If so do you have any tips/tricks on how to cut the drain pipe when it is under the sub-floor (I can’t fit a hacksaw down there). 2) In a few places I have larger gaps (1/4-1/2 inch) in my backerboard (mostly in the corners). Is it ok to just fill these with silicone, or extra mortar when I tape them (if not in the corners) or should I re-cut the pieces? 3) On one piece of backer that was difficult to cut a small 6 X 4 piece chipped off when I installed it. Should I recut the entire piece? I currently have screwed it on and it fits nicely, I plan to tape and mortar the break line. Thanks!

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Bonnie

Dear Elf,

I paid $53 million for your wall waterproofing e-book, for our tub-surround-tiling project. But the e-book doesn’t say I can use a liquid membrane over the backerboard. Can’t I? Is that in another $53 million book?

Bonnie

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Roger

Hi Bonnie,

Did you order the one for topical liquid waterproofing? Because I have specific books for different methods. If you need that one shoot me an email at Roger@FloorElf.com and we’ll get it straightened out for you.

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Janet

I have a tub of laticrete hydrobarrier and also schleuter Kerdi cloth. I hate mixing up mortar. Can I use the hydrobarrier to stick the Kerdi to the durock backer board for my tub/shower surround. Then what do I use to adhere 1/2″ thick 6″x24″ limestone tiles to the walls? Are there ANY premixed products I could use? Thanks so much!!!

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Roger

Hi Janet,

No you can not. You need to use thinset for both.

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David C

Roger,

I scrapped an existing poorly installed shower all the way down to the concrete slab and have started building a new shower from scratch. so far I have done the following:
*framed up the new knee wall and curb
*framed out a couple of niche’s
*poured and finished the concrete pre slope

now its time to install the rubber liner followed by installation of Perma Base cement backer board. Before I do this , I have a couple of questions.

1. Should I cover my concrete pre-slope with Laticrete Hydro Barrier before installing the rubber liner?
2. Should I cover my curb (I used 3 2×4’s for the curb) or any of the studs / niche’s with this Hydro Barrier membrane before the installation of the liner and backer board??

my plan was to simply install the rubber liner, using electro galvanized nails to adhere the rubber liner to the curb and walls about 10 inches up the wall and wrapped over the curb. Then I would install the backer board over that leaving about a 2 inch gap between the base of the backer board and the rubber liner. I was going to then used the laticrete hydro barrier and fiberglass “cloth” tape over all seams and over all screws. If I have enough I would literally roll it over everything but only using the fiberglass cloth in the seams corners etc. Then pouring the final concrete and begin my tile install beginning wit the floor tile butted up against the walls.

Also,

the backs of my niches are the dry wall from the closet behind my shower. Can I just liquid nail the cement back board against the dry wall and put the laticrete membrane and fiberglass in that niche Or do i need some sort of barrier like a sheet of plywood or something between the drywall and the concrete backer board that will be the rear wall of my niche?

whew!! Thanks

David

San Antonio Texas

Am I way over doing this or not doing enough?

Reply

Roger

Hi David,

1. No
2. No

If you do not have a barrier behind your backer you need to have the entire surface covered with the hydrobarrier, not just the screws and seams. Backer is not waterproof.

Yes, you can use liquid cement in the niche, but thinset works better. You also need the hydrobarrier over all the backer in the niche as well, the mesh is not required in the niche.

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dan

Hi roger,
I recently remodeled a bathroom and used greenboard with 2 layers of redgard applied over all in the shower tub area. (followed recommendation from hardware store for wall prep). then tiled all the way up to the ceiling.
After reading all of this, makes me worried I screwed up. should I be concerned about major failure? thank you for your time.

Reply

Roger

Hi Dan,

I don’t know. There is no way to guarantee a failure, we can only guarantee methods that won’t fail. Greenboard is not an approved substrate for redgard. It may be just fine, no way to tell.

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Joan

We put in a tile shower (over a tub) and used green board alone (as recommended by the building supply store) about 7 years ago. I’m in the midst of replacing the grout and caulk (a difficult job) but the tiles are all tight and “stuck” without problem. We can get behind the wall (in a crawl space) and the studs all appear dry and fine (the shower is about 7 years old). How worried should we be that we have only green board behind the tile? Do I need to use epoxy grout? If so, is that doable for a do-it-yourselfer with limited grout experience? To clarify, the tiles are already up! Thanks.

Reply

Roger

Hi Joan,

Sometimes it works just fine, most of the time it won’t. Proper installation is a matter of eliminating as many unknowns as possible, greenboard is an unknown. I wouldn’t worry about epoxy grout at this point, it won’t cure any problem that may arise.

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Lee

Hi Roger, a general question on building trends. I’ve seen shower pans with the membrane liner, cutting the slits at the corners, putting the membrane up the wall 18 inches or whatnot. It looks a bit labor intensive.

In your opinion will Redgard make that process obsolete? It seems a lot easier to just tape seams and paint two coats of Redgard to get the same result. Why bother with cutting and stapling membrane.

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Roger

Hi Lee,

In my opinion yes, topical membranes are going to make the pvc liner and traditional method obsolete. It will likely still be used, but not really in a professional capacity. It’s been happening for the last five years.

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Todd

Hi Roger. I am planning to install Kerdi membrane over Wonderboard on the walls in a custom built shower. There will be no plastic or other waterproofing behind the Wonderboard. The plan is for the floor to be a mud pre-slope covered by a PVC membrane (which my plumber has already provided), so no Kerdi on the shower floor.

My question is (1) does this sound OK to mix the PVC floor membrane with Kerdi wall and (2) if so whether the PVC membrane should run from the floor up behind the Wonderboard or if instead it should be installed in front of the Wonderboard. I was thinking that the PVC should go in front of the Wonderboard, then the Kerdi would be installed on the walls with a slight overlap over the PVC in order to channel water properly. My tile installer thought it would be better for the PVC to go behind the Wonderboard so it is directly attached to the wood framing. However, I thought this might allow the bottom of the Wonderboard sheets to get wet, which could allow for moisture penetration behind the Kerdi. If PVC goes over the Wonderboard, I could just use screws long enough to penetrate the Wonderboard and into the studs and blocking behind it.

Thanks in advance!

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Roger

Hi Todd,

That combination is fine, but the liner needs to go behind the backer. The backer should not touch the liner at the bottom, it should be about 1/4″ above the top mud deck, then it can’t wick water.

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Giles

Hi Roger

I am planning on replacing my existing shower cubicle with a walk in/wet room type of unit. This will also take advantage of the recent space I got back when I replaced my old boiler with a new combi boiler, as I’ve lost the old hot water cylinder and gained a big empty cupboard.

I’m pretty good with DIY and take on most projects – but do you think this type of installation would require professional tradesman?

Thanks for your advice.

Giles

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Roger

Hi Giles,

While always the best option, it doesn’t REQUIRE a professional (provided there are no load-bearing walls, etc.). It just depends on your skill level with diy projects.

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Weston

Preparing for a shower project I would like to use one of the topical waterproofing methods but one of my walls is exterior so it has a vapor barrier the other 2 walls are just studs. I don’t want to cause a problem with the double vapor barrier what would your recommend in this situation. Thanks.

Reply

Roger

Hi Weston,

You can either cut slits into the barrier in the stud bays, or you can simply leave it. On a single exterior wall it’s rarely a problem due to differential pressure and temperature on each side of the wall.

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Dana

Hello Roger.
I have been reading over all the comments and all, but take me for who I am, a female, blonde grandma. I had a young man come in and take out the old tub, put in a new one, put up purple “drywall” from Lowe’s. Is this suitable to put tile up on? If so, what do I need to do first? If not, I fear I will be struggling to tear it all down and re-work it myself since there is not an income to actually hire anyone else to do this. I have laid tile on counter tops before, so I have an idea of what I am doing, but I am sure I will make a mess as I go.

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Roger

Hi Dana,

Purple drywall is not an approved substrate for use in a shower. You can put the kerdi membrane directly over it and tile to that, but you may end up with issues if you just tile directly to the drywall.

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Dana

Thank you. I am not objectionable to putting the membrane up, just didn’t want to have to tear it all out again.

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Lee

Hi Roger,

Still mulling things around regarding tiling a wall. Apologies for repeating myself, but here it goes. I have an upstairs tub, the 1930 walls are wooden lathe and plaster, no cracks, the plaster is in really shape shape. My tile guy would like to rip out the paster and lathe to the studs and start fresh. I’ve done that elsewhere, yes it works, but super dusty and not pleasant work. My house is old, some day it will be demolished.

So my question. Regrading the old plaster walls above the tub, which have a couple coats of paint. Can I: 1.) apply Redguard, two coats, over the three walls surrounding the tub 2.) apply a modified thinset and 3.) apply tiles.

Or how about this 1.) Redguard over the old but strong painted plaster 2.) modified thinset 3.) Kerdi board 4.) apply tiles to the Kerdi. If the Kerdi is not critical, I would prefer to not do it. Why? My window trim is flush with the plaster. I will need to apply some new trim to accept the thickness of the new tile, I’d prefer to keep the thickness of the trim as thin as I can.

I am not expecting much water to ever hit these walls. I am over age 50, I am wanting this tile project to last 20-30 years max, at which time the house will cease to exist.

Reply

Roger

Hi Lee,

You can just rough up the paint over the plaster and install redgard, then tile away. Provided the plaster is solid it will be just fine.

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Chris

EDIT: I meant if you just want to recommend ME buying the book, then note taken. Haha it’s late…

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Chris

Dear Mr Roger,
I’ve had great joy in educating myself through your site, but I’m left with three questions that still confuse me.
I’ve tore out the old shower down to the studs and concrete floor, and will therefore start from scratch. So far I’ve bought all the materials (but can be returned if you recommend differently; Hardiebacker and TEC liquid waterproofing membrane.
Questions:
1) If screwing on substrate, will liquid membrane cover screw holes, seems and corners or do I need fiber glass mesh/cloth, and do you cover the entire board given that Hardiebacker is only “water resistant”?
2) When doing the 2 layer floor, is the membrane applied to bottom, top or both layers?
3) With regards to this article, I’m confused as to whether putting up vapor barrier behind substrate, when waterproofed, will cause your described “mold sandwich”?

I know it’s a lot, but I’m sincerely looking forward to a nudge in the right direction.
PS: if you just want me to recommend buying your book then note taken ;)

Best,
Chris

Reply

Roger

Hi Chris,

1. You use the mesh tape and thinset over the seams and in the corners, let that cure, then install the liquid over the entire shower wall.
2. If you are using a topical membrane you can either use a topical drain and do a single layer, or do a double layer with preslope, then the membrane, then the top slope.
3. It’s never a good idea to have a vapor barrier behind a topically waterproofed wall substrate.

You can also buy my book. :D

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Chris

10-4. Thank you sir!

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Charles Sponberg

Hello Roger,

I am putting in a bath tub/shower surround and plan to use HydroBan on the surface of the hardibacker. I have spoken to some people who put plastic behind the hardibacker and then put on the topical membrane on the hardibacker to protect their walls in case there is a failure of the topical membrane.

Is this a bad thing? I would be willing to put roofing felt on behind the hardibacker and then coat the hardibacker with Hydroban. If the Hydroban failed and the roofing felt and the hardibacker were siliconed to the tub the water would be trapped between the Hydroban and the felt paper (inside the hardibacker). This would be bad but the felt paper might keep it off the studs whereas without it the wet hardibacker would be up against the wall studs.

What do you think of silconing roofing felt paper to the tub behind the hardibacker, siliconing the hardibacker to the tub, and then covering it with Hydroban? Is that a problem in waiting?

Cheers,

Charles – A bit confused.

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Bo

Hi Richard. Am doing reno on alcove shower which has two external walls. Will be using Kerdi (used on other shower reno). The external walls have 6 mil vapour barrier. The Kerdi will create another vapour barrier, which will leave only 1/2″ drywall between the two vapour barriers. Is this a problem? Many thanks.

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Roger

Hi Bo,

Who the hell is Richard? :D

No, that won’t be a problem at all.

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Michael

Are you friggin kidding me! Why the hell did I not find you like 4 days ago. So I had like 5 diiferent ’tile guys’ come and look at and quote my project for me and none of were suitable enough for me so decided to go ahaed with it myself. I added a bathroom in the basement. Put a tub in and want the walls and ceiling tiled, (Also the floor but we’ll get to that later). Thought i was on a roll till i read that cement backer board still need vapor barrier behind it? F@*!# me!!! I have the bottom two rows of tile on and frankly lookin pretty good. Now to i rip out the tile and the cement board put the vapor barrier on and start again? Or finish the job and then sell the house? Please advise

Signed,
Rookie

Reply

Roger

Hi Michael,

If you want the shower built correctly (waterproof) and want it to last (not selling the house) then yes, it needs to be removed and built properly. And yes, I know that isn’t what you wanted to read.

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Leigha

Hey Roger,
I just ripped out my tile on my bathtub wall and it looks like the builders just screwed the cement board on to the dry wall. It also looks like there might have been roofing paper between the dry wall and cement board though. Do you suggest I rip out the dry wall to add in the plastic vapor barrier like you explain in this post? Or is it okay to waterproof the dry wall with either the roofing paper like the builders did, or to paint it with RedGard?
Thanks!

Reply

Roger

Hi Leigha,

It needs to be removed and replaced with a correct waterproof substrate. The only waterproofing that can be used with drywall is schluter kerdi over the face of it. Redgard can not be used with drywall.

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Richard

Oops. I meant, is it ok to add tile from the existing tile all the way up to the ceiling?

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Roger

OH, yes, you can, provided you have a waterproof substrate beneath it. Remove the drywall, add cement board and paint liquid membrane on it. Or use kerdi right over your existing wall.

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Richard

Hi. I am adding a shower to my tub. The walls are currently tile 40″ up from the top of the tub. These tile are cemented on to expanded metal which is stapled to the wall studs. Would it be ok to add tile to the ceiling or do I need to remove and replace all the existing tile and waterproof? I cannot find any information on tile that was installed on expanded metal.

Reply

Roger

Hi Richard,

The metal should have tar paper behind it – that is your waterproofing. If it doesn’t then you don’t have waterproofing (you may not since it never had a shower). In that case you would need to remove the tile and waterproof the entire thing. A liquid membrane would be the easiest method to achieve that. You can tile the ceiling if you want to.

Reply

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