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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Rich Kennedy

Have you used the USG Duroc Shower System, which appears to be very similar to the Schluter-Kerdi shower system? I read somewhere it was designed by the person who designed the Schluter system and incorporates lessons learned from that design, but I don’t know if that is true. This will be my first shower project so looking for the most reliable DIY option.

Reply

Roger

Hi Rich,

I have not heard that, so don’t know if it’s true. Doubtful, because the guy who designed the schluter system was named schluter, doubt he would do it for usg. :D It is a very good product, though.

Reply

David

That was Kerdi, rather than Kerri!

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David

Hi Roger,
I’m installing a new tub with shower with tile to the ceiling. I intent to use concrete backer board and then Kerri membrane. Will I be able to get away with using non-vitreous ceramic tiles, or should they be at least semi-vitreous? The ones we prefer are glazed, but non-vitreous.
Thanks!

Reply

Roger

Hi David,

That tile will be fine. In a properly waterproofed shower you can use nearly any tile you wish.

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Bob

Hi Roger,

I bought your book on doing a Kerdi shower installation and have a few questions:

1. I used drywall for my substrate. In your manual you suggest a 1/16″ – 1/8″ gap between each sheet on the walls. On my back wall I have the drywall horzontally with no gap – the top sheet rests on the bottom one. Is this OK?

2. You mention using silicone in the corners before putting up the Kerdi. The vertical corner has a small gap that can easily be filled with silicone. But where the drywall meets the ceiling there is a larger gap – up to 1/2″. Should I bother filling this or just run the Kerdi up to the top of the drywall and leave the gap there? I am tiling to the ceiling so the top tile would cover this gap. As this is above the shower head I’m assuming the change of plane at the top of the wall doesn’t need to be waterproof.

Thanks in advance!

Bob

Reply

Roger

Hi Bob,

1. Yes, that’s fine.
2. Just run the kerdi up to the end of the drywall, don’t worry about putting anything in that gap. No, it doesn’t need to be waterproof up there.

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Ken

Hi,

We’re building a new home and I’m doing the tile work. Plan on using Kerdi to waterproof the shower enclosure, so purchased your glorious tome on using Kerdi to waterproof a shower enclosure and I have a couple of questions.

– due to not knowing about Kerdi and Kerdi drains when we did the rough plumbing we installed a standard old-style drain and waterproofed the shower pan with a mud base and vinyl sheet waterproofing. Should I still bring the Kerdi down to cover the shower pan or is this going to give me grief with the old-style drain?

– the drywall guys went ahead and used DensShield around my shower enclosure before I’d read your book. Would have used HardieBacker if I’d read your book first. Would you rip out the drywall and replace with HardieBacker?

Reply

Roger

Hi Ken,

Just run the kerdi down the wall and about two inches onto the perimeter of the shower floor. You don’t want to cover your mud bed with kerdi now, it’ll create problems. You can install kerdi over densshield, it will be fine.

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Rob

Also I am really sorry for spelling your name Rodger!

Reply

Roger

Hell Rob, that’s not even close to the worst thing I’ve ever been called! No worries. :D

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Rob

Hi Rodger,

I have installed hardibacker as my substrate and my plan is to use regard as my waterproofing method. My corners are wider than 1/4, about 3/8ths in some spots and it has me nervous. If i mortar and tape, and regard, will that be sufficient. If not, can I use 5” strips of kerdi fabric along the corners for extra protection? If not is there anything I can do to prevent having to recut and install new sheets of backboard?

Thank you so much!

-Rob

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Roger

Hi Rob,

Mortar and tape will be just fine with the redgard in those corners.

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rp

What kind of wood should be used for the framing of the shower/tub walls?
pressure treated, redwood, or standard 2×4’s? thanks.

Reply

Roger

Hi RP,

Standard KD lumber (regular 2×4’s).

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Ron

I am redoing my shower replacing the walls with wonderboard. Should I caulk the space between the board and the ceiling before tiling, or sould I fill it in with thinset? The walls are 8 ft.

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Roger

Hi Ron,

Silicone. Thinset will cause undue stress on the board, the silicone will allow it to move with regular expansion and contraction.

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Lee

I know we have been discussing tiles and walls, but if I may ask about a ceiling. I removed a lathe and plaster ceiling (no choice) and a new drywall ceiling is in its place.

The ceiling in this bathroom, which has a shower, is now drywall. It will be textured with mud or plaster, I’m not yet sure. I do not expect any water to hit the ceiling, but I do expect quite a bit of steam and I do not have a fan (however there is a window).

Should I apply Redguard or Hydroban to the drywall ceiling prior to applying the mud or plaster?

Question #2 – I will not tile the entire room, just the shower area. The remaining area consists of: studs, roofing paper, wire, and 1/2 inch of floated cement. Over this cement will go plaster. Should I Redguard the cement before the plaster?

If helpful, this bathroom does not need to last 30+ years. I am on the wrong side of the age spectrum, but as the saying goes, still on the right side of the grass. When I am under the grass, the home will be unceremoniously demolished and replaced by something brand new, and cookie cutter ugly.

Reply

Roger

Hi Lee,

Paint won’t bond to redgard. Just use a good acrylic or latex based paint on the ceiling. Any area that is not inside the shower does not need redgard.

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Jared

Roger,

I just bought your books. I wish I would have done it earlier – up to now, I’ve been trying to piece together information from various sources. Worth every penny!
I am considering water proofing and tiling the ceiling above the shower – but really don’t want to. However, I’m concerned about moisture. The ceiling is regular drywall. The bath has properly sized ventilation close to the shower controlled by a humidistat.
What is your advice on this topic?

Reply

Roger

Hi Jared,

As long as the ceiling is painted with a good latex-based paint it won’t create any problems at all. If you have proper ventilation the drywall isn’t an issue. The only time they really need to be tiled is when there is a header across the entrance to the shower.

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Karen

I’m considering taking out my existing tub and tile surround (tile to ~74″, gyp above) and putting in a shower with a tile surround (tile to the ceiling), but am concerned about one of my surround walls being an exterior wall with a vapor barrier. If I use a product like Redguard or Hydroban to create a waterproof enclosure for the shower I’ll be creating the conditions for condensation in the wall cavity by having two vapor barriers.

Once I commit to this project, what’s the procedure for creating a waterproof shower enclosure against an exterior wall with a vapor barrier? Should I only apply Redguard to about 7′ on the exterior wall? Would it be more advisable to go with a plastic sheet installed behind the cement board with a gap at the top for air flow?

Reply

Roger

Hi Karen,

You can slice the vapor barrier in each stud bay on the exterior wall. This gives someplace for any trapped vapor to dissipate.

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Bruce (helpful Handyman)

the tile backer are often sold as a 3ft x 5ft size. Most tubs or 5ft wide.
You install it 5ft on the horizontal.

Reply

Ross

Hi Roger
In your article, “Choosing a Waterproofing Method for a Tiled Shower” you stated that the Wedi board, “is normally sold in 3’ x 5’ sheets and is simply installed directly to your wall studs.” Those dimensions don’t jive with 16″ centers. What am I missing?

Thanks
Ross

Reply

Roger

Hey Ross,

They make it in many more sizes now, but the 3 x 5 is common with that as well as other boards due to the size of a regular bathtub alcove. 5 feet across the back, boards installed horizontally, 3 feet or less on the ends, boards installed vertically. It is the most efficient size for homeowners.

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Ross

Thanks, Roger. I think I’m going to go with the Durock kind of substrate after all. I’m also considering using a product called Quick Pitch for doing the floor. It’s about a 4 x 5 ft custom shower, but the drain is in a bit of an odd location, so the QP will make it easier to get the right grade.

Cheers
Ross

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adam

Hi Roger,

Enjoying your books and teaching style. It’s quite sophisticated, despite its casual tone.

I had two quick questions:

If I’m tiling from the lip of the tub to the ceiling, am I putting hardiebacker all the way up to the ceiling? Or just above the shower?

Let’s say I’m tiling the floor ( or will be ). The floor has a concrete bed under tile under very thin vinyl. If I prime the vinyl, do I need any other prep before thin set and tile?

Thanks,
Adam

Reply

Roger

Hi Adam,

Ideally all the way to the ceiling, but a minimum of two inches above the shower head is fine. No, but I would remove the vinyl. While you can go over it, your entire installation is dependent upon the bond of the vinyl to the concrete, as well as the stability depending on the effect of water on the vinyl should it ever get wet.

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Gordy Toomey

Hi Elf, I have a big problem and I hope you can help. I waterproofed my shower with Mapei Aquadefense. I had a leak after the flood test and upon close inspection there were several small cracks in the cured coating. I tried touching up the cracks and flood tested again, better but still leaked. So then I scraped up the area down to the mud bed dried it for days, tested for moisture with Saran Wrap overnight and was completely dry so I applied 3 coats, let it dry completely between coats and let that dry for 2 days. Looked good so I flood tested again. No leaks,looked good. The next day I checked it and found leaks in three places and the product looked like an old painted board with paint stripper on it in some areas including where I had repaired. Other places were soft and scraped up in a gooie mess. The rest was still dark green. Got any ideas what happened?

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Roger

Hi Gordy,

I assume you bought it a big box store? The reason I say that is it sounds like an expired product and they are HORRIBLE about rotating product. I can’t remember if mapei puts the manufacturing date on the buckets or not, but I know there will be either a serial or batch number on it. Give mapei technical support a call (the number should be on the bucket) and describe the problem. They’ll ask you for that number and they can tell you where to go from there.

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Paul Clary

I have read all of your tips and comments concerning preparing for a tile job. Since I am planning to do a tile tub surround, I have found the information on this page very helpful. Even though I had not planned to any other prep work beyond HardieBacker, I have now decided it to be in my best interest to use a liquid barrier. So I will visit Lowe’s tomorrow morning and purchase Aquadefense before proceeding to install tile. Thank you for posting. :-)

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Kevin

I’m replacing a shower using Kerdi as the moisture barrier. I’ve already put up purpleboard (National Gypsum XP), but I’m getting conflicting opinions on mortar adherence to it (using Laticrete 317). Can I leave the purpleboard up, or should I replace it with regular drywall?

Thanks,
Kevin

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Roger

Hi Kevin,

If you leave it up you need to use modified thinset. You can use the 317 over regular drywall. I don’t know how well it would bond to the purpleboard.

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Dave

Nice site!
How can I add support of a wide edge of CBU over drywall (for wall tile) which does not extend to a stud?

Description: MBath, walk-in shower fills end of room, std pvc/mud pan + mud curb, 3 walls tiled, MR drywall required by bld dept and 6-mil VB over drywall. CBU to be screwed through VB and drywall to studs 6-8″OC except the CBU tile area that extends out past the shower wet area. That dry-area part is too short to reach the next stud. Stopping at the last stud is too short; extending to the next stud is too long. Is adhesive behind CBU to add stability a possibility or is there a better option. The opposite wall is drywall over a pocket door so no easy stud access either. No room inside the wall for additional studs. Thanks for any suggestions.

Reply

Roger

Hi Dave,

Like this. :D

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Abigail

We are adding a shower to an old bathtub. It currently has tile that goes halfway up the wall, but the house was built in the 1930s, and there is no waterproof membrane behind the tile. And above the tile there is just wall. My husband wants to just re-grout the tile and paint the walls. He thinks that will be enough to protect the walls for the shower. However, I’m worried about re-selling the home, and the mold that could grow behind the tile. I want to put bathtub walls in, like a shower insert. We’d rather not pull the tile out and re-do it all. We have many other projects to do! What do you think is our best option? Do we need to put a waterproof membrane down before we put bathtub walls in? Would it be ok to put plywood on the top half of the wall to level the surface for the bathtub walls? I’d appreciate any advice. Thanks!

Reply

Roger

Hi Abigail,

You need to have some sort of waterproofing behind your shower walls. You can use the kerdi membrane, which can go directly over what you have now, then tile on top of it. You do not want any plywood anywhere behind your shower walls.

Reply

Abigail

Hi Roger,
Thanks for the reply. We aren’t intending to re-tile. My husband wants to just caulk the tile and paint the walls, and leave it that way. I was thinking we could use the Kerdi Membrane over the old tile and wall, and place adhesive bathtub walls over it all, to avoid having to remove and re-do the tiling job and to protect the walls. The plywood would be placed beneath the waterproof membrane to create a level surface for the bathtub walls.

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Roger

Yes, that would work fine. Sorry, I’m wired for tile installation. :D

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Mike

Roger,

Thanks for the info. I’m having an issue with my install and can’t find an answer. I installed a 12″ tile wall opposite the shower head using cement board with Redgard layer on top. Followed manufacturers instructions on the shower pan install and silicone caulking where the pan/tile meet. Almost immediately little thin set crumbles started coming out from beneath the caulking. I figured at first it was just excess that was working its way out and eventually be gone. A year later it’s still doing it. Any ideas?

Thanks,

Mike

Reply

Roger

Hi Mike,

I’m not too sure what you mean by thinset crumbles. If you have a picture you can upload it here: Photo upload

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Mike

Roger,

Not sure if the pictures made it through. When I tried to upload, it came to a screen “are you sure you want to do this?” without a yes/no etc. option.

Reply

Roger
Darrin

Roger
Thanks for the site. The answer to this question is probably in your site but want to be sure I have the correct answer. I’m re-tiling my shower leaving the existing shower pan. Questions…
1. There is currently two layers of green board under the tile, appears best method is to remove all and put up cement backerboard and the membrane or could I remove the first layer and put a membrane over the other layer?
2. If cement backerboard used, should it rest on the shower pan or should there be some space between the backerboard and shower pan?
3. Same question for the tile in relation to the shower pan.?
4. Should I grout or silicone the space between the tile and shower pan?
Thanks. Liked your tips on corner shelves.
Darrin

Reply

Roger

Hi Darrin,

1. All layers should be removed.
2. Actually it should go over the flange.
3. Tile should have a 1/16″ – 1/8″ gap, that gets siliconed.
4. Oh, silicone. :)

Reply

Lee

Is is OK to put thinset on a lathe and plaster wall? I doubt there is any vapor barrier behind the wooden lathe, but the plaster is solid.

So maybe some Redguard or Hydroban on the plaster wall, and then proceed with thinset and wall tile? This is for a tub. Existing tub surround in vinyl sheet.

Reply

Roger

Hi Lee,

You need to waterproof it somehow, and plaster is tricky because you’re depending on the solidity of the wall. If it is solid I prefer kerdi (best) or a liquid like redgard or hydroban.

Reply

Lee

I think I asked my question without the correct wording. I’ve got a good 1/2 inch perhaps a bit more of 80 year old lathe and plaster.

My way of thinking is that this plaster, with no cracks, is similar to cement board.

From my experience with other walls, there is no vapor barrier on the studs behind the wooden lathe.

So if I’m looking at a bathtub wall surround that’s good solid and plaster all the way around it, could I use that plaster as a substrate for the wall tile, but as an insurance policy, coat the plaster (it’s already painted) with some Hydroban before applying thinset and tile.

I suppose the other options are remove lathe and plaster, or, 1/4 hardy board over the existing plaster wall.

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Roger

Yes, but not as extra insurance, you need to coat it with the hydroban to waterproof it. Because you’re correct, it isn’t waterproofed at all right now. We’re saying the same thing, just not understanding each other. :D

Reply

Lee

Thanks, make sense. And I have lots of experience in the “same thing but no understanding” department.

In a previous life, the Mrs. would spend money, and I would reply that we need to save money.

She told me we were saying the same thing, and I never quite got my brain around that.

Sorry to digress. I will get some Hyrdoban.

Reply

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