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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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.

Reply

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.

Reply

Roger

Hi Bo,

Who the hell is Richard? :D

No, that won’t be a problem at all.

Reply

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.

Reply

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.

Reply

Richard

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

Reply

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.

Reply

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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