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.
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!
Hi Roger,
I am in the process of having my shower and bathroom remodeled. My shower grout is covered in mold that won’t clean. I would like a waterproof tiled shower and have just started researching the best products out there on the market. My Tile guy said he can use Durock, but my tile distibuter said he stopped carrying Durock about 3 years ago and is recommending Fiberock. He claims that it’s a much better product than Durock. Can you please advise me on this so that I can make the right choice and not have to deal with water leaks and mold?
Also, any recommedations on grout seals would be appreciated. Thank you!
Hi Anna,
Fiberock is a good product. It is not, however, waterproof. Neither is durock. They are both simply a tiling substrate, the waterproof aspect is in the form of either a vapor barrier behind it (over the studs) or a waterproofing membrane over the face of it.
Cement backerboards ARE NOT waterproof.
If you haven’t read my shower waterproofing manual you can download it and it will explain the different methods with pros and cons of each.
We built a house a year ago. I’m pretty sure we have no problems in how the shower was installed, BUT…..i’m not sure if this is a preventable problem in the future. We had them use epoxy grout. It has dried and cracked where the floor meets the wall. Is there a way to prevent this? We are going to clean out the grout and redo it. Is there something we can do to prevent this in the future? I really don’t want to regrout every year. This has also happened in the kitchen and laundry room between the granite counter top and tile backsplash.
I had this problem in my last home also. My cure was to sell the house. I won’t be selling this one.
Hey Phil,
All changes of plane need to be filled with flexible sealant. This simply means that corners (all the areas you’ve described) need to be caulked or siliconed rather than grouting. Silicone can compensate for structural movement, grout, even epoxy, does not move, it cracks instead – as you now know. Remove the caulk and get a silicone that matches your grout. Most grout manufacturers make a colored silicone that you can match to your grout.
HI Roger,
I read your comments regarding substrates and see that you are fond of the Kerdi system. You usually refer to the Kerdi fabric. My local tile store has Kerdi Board and I was planning to use it for my tub surround. While I was there, the sales person pushed me toward Denshield due to cost. I bought it and immediately began questioning myself. The difference in cost between the two products is only $60 for my project which will not break my bank. I just want the best solution.
I have a few questions:
I live in South Florida and my tub surround has the long wall backed against the outside of the house constructed of concrete block with pressure treated furring strips. The two short walls are constructed with galvanized metal studs instead of wood.
1. If you had the choice of Denshield and Kerdi Board and cost was not an issue, which would you select and why?
2. Which is easier to install? I hate taping drywall.
3. When transitioning from Kerdi Board to drywall, would you use mesh or Kerdi fabric and how do you keep the transition level so the tile is level.
Thanks!
Hi Tom,
I would select the kerdi board. It’s a lighter product, easier to cut and has a more visible coating. Even if there is a pinhole in the coating of kerdi-board the core is absolutely waterproof. The densshield core is waterproof, but still a gypsum-based product. If your transition is outside the wet area you can use mesh tape, if inside use kerdi-band. The transition is just skim-coated.
We have put hardibacker board in the walls of the new shower we are constructing. What order do we use to put in the floor, tile walls, and ceiling in? We do not want to cut the tiles because they are 40×13. We want to use curdi system for waterproofing. It is on a concreate slab floor. Should we build the ceiling first? Should we put in the porcelan tiles first? Should we put in the pebble floor first? Confused!!!Richard
Hi Richard,
When using pebbles on the floor do the ceiling first, then the walls, then the floor. It’s the cleanest transition. When using flat tiles on the floor do the ceiling and floor, then the walls.
Roger,
From you description regarding use of liquid membranes, is sounds as if it is acceptable to apply them directly to drywall. Am I reading this correctly?
Hi Brett,
No, you aren’t. The ONLY waterproofing acceptable over drywall is kerdi. All liquid membranes require cement backerboard.
Great information. I had a shower remodel done with Kerdi system. After the tile crew put the membrane on the floor and installed the drain system, I realized that the shower floor slope was too steep (1/2-1″ fall per foot) for the small space. To reduce the slope to 1/4″ – 1/2″ fall per foot, they put a layer of thinset on the kerdi membrane. There was enough extension on the kerdi drain to make this possible. This new thinset bed wasn’t finished on top to be particularly smooth. After that dried, they installed the tile. My question is do I need to worry about water collecting between the tile and thinset base and not weeping correctly since the tile was not installed directly on the membrane? I have a few areas of the shower floor where the grout seems to stay wet for a long time and I am worried it is wicking moisture from underneath but have no way to know if this is true or it is just residual water seeping off the shower doors. Thanks for your thoughts!
Hey Stan,
It’s not weeping water, but it is holding it. Water will still drain correctly, it’ll just take longer to do it since it needs to drain through a thicker layer of thinset. The shower is still (I’m assuming it was initially) watertight, the extra thinset isn’t going to change the function of the membrane, but it will change how quickly and effectively it drains water. It’ll still happen, it’ll just take longer. That’s why you see wet grout for a longer period of time.
We removed our old tub and fiberglass tub walls and now have the new tub installed. The tub surround area is down to the wall studs. Do we install backerboard directly on the wall studs before tiling? Or do we drywall first, then put thinset and backerboard? If we do not use drywall, the backerboard is not thick enough to be flush with the adjacent drywall on the rest of the room.
Hi Laurie,
Your backer is attached to the wall studs. Depending on how you’re waterproofing your shower you’ll need a membrane either behind it or in front of it. If you have no idea what I’m talking about you should download my free shower waterproofing manual, it will explain the different methods.
Thank you so much for the free shower waterproofing manual!! I still have a question, tho. (of course, don’t we all) We will probably go with the traditional method and put plastic between the studs and the backerboard. But how do we make the backerboard flush with the drywall that is next to the shower walls? The drywall is 5/8″ thick. Do we add pieces of wood to the wall studs to take up space?
You can staple regular cardboard drywall shims over the studs to bump it out flush with the drywall.
Hello Roger,
I am installing a shower pan. I heard to use sand underneath. Do you know if this is ok or should I should I use cement to lay pan down?
Hey Dwayne,
No sand. The proper method depends on what you’re installing it over. Read through this, it’ll explain it all: Making a shower floor for tile
Inhave ripped apart my interior shower space down to the studs and the floor of it is the concrete foundation. Since this is level do I need to put a substrate down so there will be a slope towards the drain and if so how thick should I make it at the outer edges and then sloping in?
Wally
Hi Wally,
You need to create a shower floor from deck mud. If you read through this five part post: How to create a shower floor it will give you all the answers you need. That little search box at the top will likely lead you to any other answers you may need as well.
what do you know about tile redi products and are they good ?
Hey Don,
Comments are about 50-50 with likes and dislikes. I don’t like them, but I prefer building my own pans. The need to work with epoxy setting materials as well as getting absolute support beneath it put a lot of people off of it and lead to a lot of problems and questions about them.
When installed correctly they work very well. There is no room for error at all, though. One thing wrong and it compromises the installation.
We are first time tilers.. We are scared to try making our own shower base / pan so we bought one that is ready to tile, we will be tiling the walls also. 2 of our shower walls are outside walls so we are kind of worried about it not being warm enough. Here’s where our question comes in. We understand that we need 6 mil plastic, behind the hardibacker but do we put them directly over the insulation or can we put drywall up, then the 6 mil plastic, then the hardibacker??
HI Melissa,
It goes directly over the insulation. Putting drywall up first creates all sorts of problems – trapped moisture which can lead to mold, you’ll have an extra 1/2″ where the shower meets the bathroom wall which you’d need to do something with, etc. Tile is an extremely effective insulator, as long as your insulation is good you shouldn’t have any problems at all. I live in Northern Colorado where it gets sub-zero during the winter and it’s not a problem here.
Hi Sensei Roger!
Thank you for all of your help! I continue to study all of your teachings, but was unable to find information in the comments on change of planes in relation to drywall. I’m sure the info is probably buried deep within the comments, but after 2 days of comment digging, I have grown tired.
We installed drywall above the tub in our bathroom. Kerdi installation is the next step. You mention using caulk or silicone at changes of plane with other substrates. Should silicone or caulk be used at the changes of plane on the raw drywall (in the tub and niche), before I install the Kerdi?
Thank you again for all of your help!
Holly
Kansas City, MO
Hi Holly,
If you’re using kerdi you don’t need to do anything else to the drywall except install it.
The kerdi ties it all together as well as sealing the corners / changes of plane. At the tub you want to silicone between the back of the kerdi and the face of the tub flange to create a waterproof barrier between the tub and kerdi.
Roger,
I do really enjoy your website, but alas I can’t seem to get around the personal human error factor. I am working on a shower and built the preslope and curbs with my liner etc but the walls behind the backerboard were not straight :-( I have discovered the hard way that the backerboard did little to straighten them either. The wall sticks out more as it rises. maybe as much as a half to a full inch over 8 feet. I now have the lowest set of tile dry on the wall beautifully level, but the second row sticks out further than the first no matter what I do… I finally clued in to how bad it will be and pulled the second row before it dried, but I will likely have to pull out the lower row as well.
Can I put in something like fur strips to make a level rib cage and then fill it in with thinset to and still put tile on outside of that? At what point is there too much thinset. I could always just add more backerboard at its worst potentially… Is there a way I can avoid tearing out back to the studs?
Dismally yours,
Stoph
Hi Stoph,
Most thinsets can only be built up to about 1/4″ or so – and that’s pushing it. You can install screed strips and fill between them with wet mud. You would need to do that with the entire shower though, and it needs to be at least 1/2″ thick. There is nothing you can add onto it which can be feathered down like you need it to be. Your best option would be to remove the backer and begin again. I know that isn’t what you wanted to read. Sorry.
My Kerri has some air bubbles in it close to the edge of the tub and has some loose spots where it meets the tub. What can I do about this
Hey Terry,
You can cut it out and install a patch over it.
Hi Roger,
when is the time to put the shower threshold or whatever you want to call it on top of the curb? Do you do it after all the walls are tiled? My husband says we do it before putting up the wall tiles that will abut it. He says we will cut those tiles to fit around it. It seems to me that it should go on after you put all of the tiles up on the wall around it as well as the tiles on the curb vertical surfaces. Save our marriage?
Hi Janice,
Don’t know if I can save the marriage or not, but I can answer your question.
It doesn’t matter. Seriously. It’s a matter of personal choice (of which each of you have opposing…). I prefer putting the threshold cap on first, then tiling around it. But you can do it the other way too.
I was told, its ok to use Schluter Kerdi over greenboard as a substrate. Is this correct? Thank you.
Hi Kevin,
Yes. It can be used over greenboard. If the greenboard is not yet installed then regular drywall is actually a better option, but greenboard is fine.
Thanks Roger, but can you explain why regular drywall is better? Thank you, Kevin.
Greenboard is no longer approved for use in wet areas. It was found to be an excellent food source for mold – not exactly the intended purpose.
Roger if I could bother you with another question. We are using a river rock type tile on our shower floor. Rocks are 1 1/2 inch to 2 inch, round and smooth on top. In this case would it be OK to tile the walls before the floor? Thank you, Kevin.
Yes, it’s actually much easier and looks better.
what is your opinion on using tyvek behind hardie backer in a tub/shower surround? leaving the tyvek slightly longer than the hardie so it drains into the tub at the flange of the tub?
thanks for your advice
Hi Tracie,
It’s not an approved installation procedure for tile or tyvek. That said, no reason I can think of it wouldn’t work in lieu of regular poly sheeting. It’s a better product for that type of application.
Hi Roger,
We are in the process of re-doing a shower pan that is only a year old because the installer used something called Pro-slope in the bottom to make the required slope. The problem was there was substantial space between the lower flange of the drain and the top of the Pro-slope so the waterproofing membrane was rubbing on the edge of the flange and tore allowing all of the water to come through to our downstairs! AAAARGH! Anyway, now that we’ve figured that out my question is whether or not Hardibacker board needs to have some sort of moisture barrier behind it even it the walls of the shower are all interior walls? Also, is a plastic weep hole protector a suitable replacement for the pea gravel? Thanks!
Hi Gail,
Yes, absolutely your backer needs a membrane of some sort. Being interior walls only means that if no barrier is present then all the water will be contained inside your house – in the wall cavities. Yes, the plastic weep hole protectors work well in place of pea gravel.
Hi Roger,
I am putting a 5 foot marble sill over my shower curb. Can you tell me how much the width of the sill should extend beyond the curb? Should both sides extend beyond the curb? Thanks!
Hey Janice,
It’s normally 1/2″ on each side, although there are no hard and fast rules about it. 1/2″ is normal.
I have durock tub surround and the top 1 ft is greenboard. I may have to slightly tile onto the greenboard to cover the seam. It will only see steam and prolly no direct water at that level. Any thoughts?
Hey Jeff,
It’s not a problem up that high.
For a shower floor: after presloping with deck mud (mapei 4to 1) and then using ARDEX 8+9, can i then tile over that? or do i need a second layer of deck mud. And what about weep holes for the drain if i only need one layer of deck mud?
Hi Bruce,
You can do either. Ardex 8+9 is approved as both a topical membrane or for use as an in-bed liner. If you have a topical drain stick the tile right to it. Since you asked about the drain you likely don’t have a topical drain – in that case install a top mud bed. If you haven’t yet created the pre-slope you can do a single layer with the divot method.
I have green dry wall over my ICF (Insulated Concrete Forms -essentially 2 and a half inches of Styrofoam and 6″ concrete behind that) wall. Should I remove the drywall and install the tiles on the Styrofoam or can I just put the durarock over the drywall and waterproof from there?
Thanks in advance,
Eric
Hey Eric,
You need to have a proper substrate of some sort – the styrofoam isn’t it. It would be best to remove the drywall and replace it with backerboard.
Roger thank you the recommendation. One more question after taking the 1/2″ green board down, do you think water proofing with UGL “Dry Lok” will suffice? That is the product I used to water proof the exterior prior to backfilling the foundation a so far so good. Thanks. -Eric
Hey Eric,
You can not use Drylok on a shower substrate. Your shower sees a hell of a lot more water than the exterior of your house – more than a rainforest, in fact. It may work, I honestly don’t know. I do know it’s not approved for that and if it were up to the task I’d be willing to bet they’d market it for that.
Ok thank you for the prompt reply!
Hi Roger,
Does the wall made of plestered AAC such as YTONG need waterproofing?
Thanks in advance,
Daniel
Hi Daniel,
While AAC has about half the compressive strength as normal concrete (or concrete boards) it is still a fairly low density product. It will absorb water and transfer it to the substrate beneath and/or behind it similar to normal concrete board. So yes, it should either be waterproofed on the surface or have a membrane between it and the wall framing.
I’m remodeling my shower and created a custom shower with a pvc and mortar bed shower pan. I used the heavier/thicker No. 30 felt paper as a vapor barrier, is this okay? I have not mortared and taped the hardieboard so I still have the option of taking the felt down. Also since I used the felt paper is it still ok to use 1 coat of Redgard to help prevent cracking or should I avoid using Redgard altogether? Would it be better to take the felt down and just waterproof with Redgard? Thansk in advance for your help!
Hi Jody,
The felt paper is fine. Redgard is a better option but should you choose that you’ll need to remove the felt.
So, after having 1 too many beers I ordered one of your books. Of course the wrong book. I ordered the traditional water proofing method, when in fact I needed the liquid membrane water proofing method.
With that in mind, I have a question. I just put up my backer board. I used HardiBacker 500 1/2 inch. I work for ARDEX, so I am using their waterproofing membrane called ARDEX 8+9. It rolls on just like the laticrete stuff.
My question: Since I am using this liquid membrane and the mesh for the corners and changes of plane, do I need to still tape and mortar my joints before applying the liquid membrane? I thought the membrane would take care of that since it has the mesh as well.
Confused as usual… but finally starting to get a semblance of my bathroom back.
Thanks for your help,
Jess
Hi Jess,
Yes, you still need to tape and mud the seams. You will not need to use the mesh with the liquid over those, just in the changes of plane and around the drain. Check your email.