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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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

Reply

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.

Reply

Roger

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

Reply

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

Reply

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.

Reply

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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