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, thanks for the great info. The builder of our home put the green drywall up in our basement shower saying it would be fine to tile over, just as cement board. I think that is incorrect. What should I place over the greenboard now that its there before I tile the shower?
Thanks for the help
Hi Denis,
You should place nothing over the greenboard. You should completely remove and replace the greenboard with backerboard. Greenboard is no longer approved for use in wet areas (since 2008). You can put the kerdi membrane over it – but that is the only other option.
Wow, I am glad I found your site. Finally 5 years after our remodel I am ready to tile and finish our master shower. Your comments and responses to the questions posted have been helpful. Yet….
Our shower has greenboard on the wall. I want to do this right so I am asking for direction. Do I:
1) Remove greenboard, hang a vapor barrier, hardiebacker then coat with red guard?
2) Coat green board with red guard, hardibacker and coat again with red guard?
3) Hang caper barrier, hardibacker then coat w/red guard?
4) Some or none of the above?
Thanks for your wisdom.
Hi Steve,
5) None of the above.
If you are using redgard you need to remove the greenboard altogether. You need hardi as your backer. You do not, however, want a vapor barrier behind a backer with a topical membrane on it. (Don’t know what I’m talking about? Go read this: Waterproofing a shower
)
Number one was the closest if you get rid of the vapor barrier. Just remove the greenboard, hang hardi and coat it with redgard.
I am building a new shower and have a roll of Oatey shower liner. Is it reasonable to use this as a wall membrane, as well as the pan liner. If so, would I use a modified thinset as an adhesive to the backerboard.
Thanx,
Steve
Hi Steve,
Nope, nothing sticks to it. Nothing’s supposed to. Modified thinset will simply slide or peel right off of it.
Oh , I forgot. Im using Noble ts for waterproofing. So I’m not mudding and taping backer board. Do I need to put silicone in corners after putting up backer board, to keep thinset out to allow for movement?
Sorry didnt hit reply for one of my other questions. There is so much to learn about all of this. Stressing out a little! When using waterproofing membranes like kerdi or noble, can you run one continuous sheet around tub/ shower wall or do you have to do each wall separately and overlap seams? If you can not run continuous . Do you have to use the inside corner pieces that they sell or just overlap seams and use sealant ? Wasnt sure do to wall movement and affect on tile.
Hi Mary,
No worries. That’s mostly for people who have train-of-though writing and post a new question, in a new thread, with every thought.
You do need to place silicone in the corners to keep thinset out. You can run one continuous sheet horizontally around the shower, but your walls need to be absolutely plumb (level top to bottom) or your sheet will run up or down the wall after you turn the corner. You can just overlap the seams using the sealant – no matter which direction you go with it. The orientation isn’t going to affect your tile at all.
Thank you so much again Roger. I have gotten more useful information from you and your site than anywhere. I love the doing it right attitude.
Hi Roger,
Question today is. Studs on back wall arent so level with each other, I guess you could say it that way.From one stud to the next if I lay level across them. When I go to install backerboard I would assume I need to shim these. What do I use to shim with. I have a box of 12″ long shims. Will that work or is that too tedious and are there longer shims available or do I make my own. I thought about just putting in another 2×4 , but for some reason there are a lot of extra 2×4’s in the wall already. It thought it would bring it too far off 16″ on center, also window on that wall.
Thank You
Hey Mary,
You can use regular drywall shims. They are sold by the drywall (no shit elfman!) and are four feet long. They are only about 1/16″ thick, but they’re cardboard so you can stack ’em up to whatever you need. You can also add 2×4’s (it’s called sistering your studs), your studs can always be less than 16″ on-center, doesn’t hurt anything.
Went to local stores, you know which ones I mean. The ones that claim to be a home improvemt store. Ridiculous they have no idea what drywall shim is. I have a question for today though. Is it ok to use marble, granite or other natural stone for a shelf in shower niche? Or is it better to use some other solid surface? Box store said marble is to porous.
Much appreciated
Hi Mary,
It is absolutely fine to use any type (almost) of natural stone for a shelf in your shower. Doesn’t matter if it’s porous or not. If I built showers which were not waterproof I too would be concerned about the porosity of the tile. If your shower is properly waterproofed it doesn’t matter, does it?
Doing a small bathroom. getting ready to work on tub shower wall. using porcelain tile on walls.Dont even have cement board up yet. Having trouble deciding wich waterproofing method to use. Kerdi , noble membranes or something like hydroban or A plus 9 I think its called. They said its a roll on plus putting membrane in corners and on seams. so confused dont know which route to go. Everyone has different opinion on internet. Local home improvement stores in my area dont even know what Im talking about when I say I want to waterproof the shower wall. They have never even heard of kerdi or noble. Help!
Hi Mary,
Have you downloaded my free waterproofing a shower manual? It explains the time, cost and labor factors as well as the pros and cons of each different method. You can find it here: Waterproofing a shower.
Thank you Roger
Roger ,
Im having trouble getting your manual. I click on link , put in info, but there is no suscribe or submit box or anything to click to send my info.
Help Please
I just sent you an email Mary. Sorry about that.
Thank you so much Roger. I have another quick couple questions. Local box store said I can use square notched trowel to install my porcelain 12x 12 tile on wall. in tub area. Im not sure if its an actual floor tile or not. I do remember him saying you can use floor tile on walls but not wall tile on floor. I cant find on box whether its floor tile or not , but I thought rule was generally V notched trowel for walls and square for floors. I was thinking to do an 1/8 “grout line with sanded grout. I placed my nine tiles on floor and measured. I could actually go 1/16″ but its my first tile job and was worried about keeping everything straight with such small grout line. Is this the correct way. I know standards say 1/8 ” or less to use unsanded , but thought I had read on your sight I can use sanded on 1/8″. Thank you so much for all your help. No husband here( not that , that would help Lol )
Hey Mary,
Yup, a husband would just get in your way.
A tile that is specifically a wall tile is normally 8×8 inches square or smaller and usually soft, white ceramic throughout. You can use floor tile on a wall – and you do want to use a square-notch trowel for them. Yes, that is the correct way to figure out your grout line. And yes, you can use sanded on smaller grout lines, I use it on 1/16 all the time.
Floor Elf
I thought I posted my question yesterday…but I think the interwebs may have eaten it…so here goes again. My wife and I are building a shower in our new bathroom, while the bathroom is new the house is not, the walls are lath and plaster, I know that drywall as a substrate is a no no… but my question is do I have to rip out all that plaster and lath or is it possible to mount our backer board over the plaster and use a liquid water membrane over that backer. The plaster is in good repair and if I don’t need to do the demolition that would save time…but I also don’t want to create a “mold sandwich” or anything else that will make me sad later.
Hi John,
You did ask yesterday – right here: John’s question he asked, then got drunk, then lost…
I answered right under it.
hello, i have hardie backer material installed on the walls on my shower project and i am installing shluter kerdi shower kit. my questions is, what thinset would you recommend other than ditra set, its not available where i live, that would work just as well? regular unmodified thin set would get compromized cause the hardie baker board would suck the moisture out of it , not allowing good adhesion of the kerdi.
Hey Carlos,
That happens with ditra-set as well. Take a sponge and wash down your backer before you install the thinset. You want SSD – saturated, surface dry. Backers are thirsty – give ’em a drink.
You can use Laticrete 317 or Mapei KeraBond – either work just as well.
Roger –
I’ve read varying reports on installation of drywall for showers under the Kerdi – one specifically mentions to install the drywall horizontally, as it’s stronger. My research on the drywall companies confirms that they are stronger horizontally. However, when doing a tub surround and you’ve got a 78″ x 32″ opening to fill it makes sense to mount vertically and have one piece, rather than 2. I would think that might be a little stronger. (though my expertise lies in taxes, not engineering). I can add more screws if need be but I want to make sure my wall isn’t going to come down while I’m showering. Thanks!
Derek
Hey Derek,
Install your drywall in any orientation you want. While it may be initially more sturdy once you get the tile on it that wall isn’t gonna move at all (provided you have proper 16″ on-center wall studs). You would be amazed at how much tile stiffens a wall. Your wall isn’t going to come down.
Oh great Floor Elf!!
We did a major renovation to our house 2 years ago but did not have the $$ to finish the shower in the new bathroom on the new second floor. The shower valve has been installed as well as a shower pan. The builder put in drywall and primed and painted (latex) the shower alcove to satisfy the inspectors (orange peel texture). The ceiling is sloped along the roof line and so the ceiling will also need to be tiled. (88″ on one end, 67 on the other) I should have requested cement board, but the builder never returned calls or e-mails. Still don’t have any $$, so I’m doing this myself. Anyway I’d like to use Schluter-Kerdi and want to be sure leaving the drywall will really be OK. I emailed Schluter — they said the drywall is fine as long as latex paint was used. Should I take out the drywall and put cement board on the side with the shower valve just to be sure?? I just don’t want problems down the road.
You are a kind and wonderful Floor (and Shower) Elf — a GIANT among elves.
thank you! ~ Rose
Hi Rose,
Yup, the drywall will be just fine. Provided you install the kerdi correctly you won’t have any problems at all with it – no water will ever get to it.
Hey Again Floor Elf,
I’ve just finished installing the Kerdi membrane with Ditraset mortar. I used a 1/8″ x 1/8″ trowel, mixed the mortar to what seemed the correct consistency, applied the membrane and proceeded to press it into the mortar. Of course mortar came out of the sides as I ran the drywall knife over the membrane. I’m just concerned because even after 24 hours the Kerdi can be peeled back at the edges. It’s more secured after 48 hours but it not at the point that it cannot be removed. I’m concerned I may have removed too much mortar when I smoothed the membrane. I know the mortar has a complete cure time of 28 days. Will the Kerdi become more secure with more time? I had pulled back the membrane when the mortar was still wet and the layer of mortar at that point was pretty thin. How thick should it be? I’d hate to have the tiles and Corian start pulling the Kerdi away from the cb.
Thanks Floor Elf
Hey John,
Stop doing that!
It will be much more secure after 28 days, but you’ll still be able to peel it. That, however, is not how tile pulls on the membrane. If you want a fairly accurate representation of how easily it would become unbonded peel up the bottom portion of the wall and then pull the kerdi straight down off the wall – down along the face. Your tile will only put downward pressure on the kerdi – never outward. It won’t peel the kerdi off the wall. Really. 
Roger,
In a shower with traditional waterproofing on the walls (6 mil plastic behind 1/2″ durock), I was planning to tile the walls with thinset for 12×12 tiles. Is this the right approach? I’ve tiled walls (not for a shower) with the glue before, but just wanted to double check that thinset was the right option for the shower.
Thanks,
Mike
Hey Mike,
Yup, thinset is the correct product for your shower walls.
Hi Floor Elf,
This is a great website with tons of useful information. We are going to be tiling our shower and using Kerdi for the walls and floor for waterproofing. We just had a new shower mixing valve installed and have not yet put the drywall up on the plumbing wall. I am not sure what to do for sealing the mixing valve because the Kerdi mixing valve seal is for a 4 1/2″ opening and our Kohler mixing valve requires a 5 9/16″ hole in the wall. I searched online and was unable to find a Kerdi valve seal in a larger size. What is the best way to waterproof in this situation? Should I just run the Kerdi up to the edge of the hole and rely on the valve trim gasket for waterproofing? It seems like I need to have some sort of waterproofing seal behind the tile that will seal the hole and prevent water from getting to the drywall. Any suggestions you have would be much appreciated.
Thanks,
Greg
Hey Greg,
Run the kerdi up to the hole then as you are installing tile run a bead of silicone around the perimeter of the hole. As you install your tile it will sandwich the silicone between the tile and kerdi. Water running down the wall will run around that bead of silicone rather than into the hole. The trim gasket will prevent water from getting into it from the face of the tile.
Hey Tile Elf,
In the steam shower we’re building the walls will be tile but we’ve decided to use 1/4″ Corian for the ceiling. The piece will be 36″ x 56″, so it’s not too heavy at all. I don’t know if this is up your alley or not but I was wondering what your input would be about which product to attach the Corian to the Kerdi covered Durock.
Corian recommends using silicone. If this was a vertical wall section I would have no reservations but I’m a little concerned about the holding ability in a ceiling application.
I’ve considered using unmodified mortar and can’t really find any arguments not to except that I’ve found no comments regarding this combination that goes beyond about 2 years usage and there were no problems. The only arguments I’ve seen against mortar is that Corian recommends using silicone.
I had intended to use a product by Liquid Nails designed for adhering stone and solid surface products. I admit this sounds like a no-brainer since it is a construction adhesive and designed for solid surface materials.
I’m just wondering what kind of input you would have on this.
Thanks Floor Elf
Hey John,
Your ceiling is sloped – right? RIGHT???
I would use either Laticrete 317 unmodified or Laticrete 310 epoxy. The epoxy would be a better option. You can also use a rapid-set modified thinset over kerdi, so that’s an option. Do not use silicone – it won’t stay.
Just out of curiosity, and because I honestly don’t know, have you checked with corian to ensure that the product is approved for use on the steam shower ceiling? Will it last without warping? I would call them and make sure that won’t be a problem. I know some hard surfaces can warp in higher than normal heat.
Hey TE,
We did check with Dupont Corian and the product will withstand the temperatures however, it is possible the Corian could become discolored when subjected to high heat such as around the steam nozzle. For this reason the Corian warranty is void when used in a steam shower. One of those accepted risks.
Thank you for the Laticrete suggestions. In reading the info on the 310 epoxy it says that it maintains it’s no-sag properties in temperature up to 95F. Obviously the steam is hotter than that when emitted into the steam room and it begins to cool immediately, but ideally steam rooms should run the temperature range of 110F to 115F. Do you think this would be a factor?
Thanks for backing up the doubts I had about silicone used as a ceiling adhesive. Just didn’t seem right.
Regarding the ceiling, we did a lot of research into sloping the ceiling. There is much information and advice that suggests sloping is advisable, however there is also information and a company out there that performed experiments on the formation of water droplets and the dripping time involved and the results indicated that in a residential size steam shower it took over 42 minutes for enough steam to condensate and form droplets on the ceiling. Even then, it’s not a rainshower. Research showed the average time a person sits in a steam is 21 minutes. In a steam room that operated for longer periods of time a sloped ceiling is highly advisable. But to answer your question, we decided to forgo the sloped ceiling. Time will tell.
On a serious note, your website is so informative and helpful and has helped us immensely. Your quick replies and information presented in a logical and instructive form is greatly appreciated. The depth of the information available on your website is immense and useful. Thank you for your effort. I don’t know if you’re sponsored or not as I don’t see any advertisements, which is also nice. Maybe you just like liquid donations?
And I tested your explanation on the verbalization of Floor Elf and Tile Elf. You are correct, Floor Elf does blow fetter off the tongue.
Hey FE,
One other question regarding Laticrete 317. Laticrete instructs to modify with 3701 for use with porcelain tiles, which we will be using on the walls. Kerdi warranty requires the use of unmodified mortar. Would you use the 317 unmodified with a porcelain tile to retain the Kerdi warranty or would you follow Laticrete’s instruction?
Thanks Floor Elf
I don’t rely on any manufacturer warranties – this frees me to do whatever I damn well please.
I normally use modified with porcelain. However, if you want schluter’s warranty you’ll need to use the 317 unmodified. If you aren’t concerned with that – get some 253 and use it.
I’m a lotta help, huh?
Hey John,
The non-sag time of any setting material is only applicable until it cures – after that it isn’t a factor. Thinset may be a better option as epoxy can become soft when heated. I haven’t had any problems in any steamers I’ve used it in, but that doesn’t mean that it can’t be a problem.
Hey Floor Elf,
Long time reader, first time writer. I have a question. Maybe more.
We’re building a steam shower. The walls are Durock, covered with Schluter Kerdi. In trying to ensure all openings into the shower are completely sealed we’re using the Kerdi pipe seal on the shower inlet. The steam unit we’re using is from Thermasol and the steam inlet is actually a 2.5″ diameter brass housing. They call this the steamhead housing. I knew you’d like that. Into this housing slides the……….steamhead. Anyway, in trying to figure out the best way to attach the Kerdi membrane to the outside surface of the brass steamhead housing to insure a complete seal of the shower enclosure, we have come to a little problem. Schluter Kerdi doesn’t make a pipe seal in the diameter we need for the brass housing. They sell a Kerdi Flex which is their caulking but we’ve read that the caulking will not hold up to the temperatures of a steamhead. We have thought of maybe using a high temp caulk, such as one used on a chimney. So have you run into this this before or do you have any suggestions for a solution?
We’ve used your site extensively and it’s helped guide us through many questions we had. For that we thank you. I guess the only other question that perplexes me is why are you not the Tile Elf instead of the Floor Elf? Also, when you sit down to answer questions do you sit down with a ……….pepsi, or do you wait until one of the questions forces you to get one?
Thanks Floor Elf.
Hey John,
Steamhead housing, huh? Originality is dead.
Not sure where you read that kerdi-fix won’t handle the heat. Regular caulk, and some silicones, won’t. Temperature variances for kerdi-fix range from -40c (believe it or not – that is -40f as well) to 100c (212f) and up to 180c (356f) temporarily (30 minutes max). It should handle the temperature differences just fine. That information is from the tech data sheet for kerdi-fix.
I am the TileElf as well – type in TileElf.com and see where you end up.
FloorElf was chosen because:
1. You don’t sound drunk when you say it
2. It is easier to distinguish the R and the E next to one another rather than two E’s
3. I had absolutely no idea this website would become what it has. (size-wise)
But now I’m stuck – I’m good with it.
i have a vapor barrier over my studs 4 mill, then i have durock over that. can i just use mapie aquashield over that?
Hey Larry,
You need to have either a vapor barrier or a topical membrane – not both. If you already have the barrier you should not use Aquashield over it.
I am tiling a bath for the first time. I have installed 1/2″ cement backer board on the shower walls and plan on taping,mortaring, than using 2 coats of Mapelastic HPG on the walls. I am installing a plastic shower base. I have used mortar (concrete) under the base to be sure it is stable, then screwed it to the wall using proper back board screws on the base flange. The area under the base was also sealed with Mapelastic. If this all sounds good so far, here are my questions:
The base has a 1/8 to1/4″ plastic flange at the wall. I carried my cement backer board behind it to the floor. Can I just fill the 1/4″ space w/ mortar when installling the tile and hold the tile 1/2″ below the top of the flange (but not onto the base)?
I still have a 1/2″ space between my cement floor base and the plastic shower base lip (the shower base was installed to level leaving this space) which i would like to fill with a product that will provide some support. Will my tile mortar be good for this or should I use another product?
I would like to install some “shelves” in the corner of the shower for soap,etc. What is the best method to make these? I have studs behind my cement board to attach them to with screws.
Thanks for your advice.
Hey Craig,
Yes, you can shim the tile out with thinset at the flange if you want. Make sure to silicone the corner where the base flange meets the backerboard well.
You can use mortar for that or spray foam, which works well as long as you don’t overdo it.
Read through How to make a tile shelf.
Roger,
Ok I have a shower walled with green drywall. I was going to use cultured marble, but may use tile now. Do I need to rip it out and start over, or is there something I can put over the top of it. Above you said something about using Kerdi over the top of drywall. I don’t think my installer knows what it is. He wants to take out the green stuff and start again.
Hi Rebecca,
The ONLY product that can be used over drywall or greenboard is kerdi. If he does not use kerdi it needs to be taken out and replaced with cement backerboard.
Thank You for promoting the use of proper shower construction and not promoting drywall in shower. Your one of the few sites online that does this.
Drywall has no business in a shower build and too many people promote it’s use.
Thank you for making a difference.
Best,
John Whipple
By Any Design Ltd.
Thanks John. This, however is the second place you’ve posted online in a manner which makes me think you don’t know who I am – you’ve known me for years – don’t let the ears fool you.
I’m Roger from TileArt.
You’re correct – drywall has absolutely no place in a shower construction. EXCEPT behind kerdi – like the manufacturer recommends. It is not required behind it, backerboard is a better option, but it is an acceptable substrate behind kerdi.
We’ve had this argument before. You don’t accept the manufacturer’s recommendation – that’s fine. I do – that’s fine as well. With this site I recommend techniques and procedures set forth by the NTCA, ANSI, and the TCNA. I don’t live in Canada. I do not use TTMAC. All literature these groups put out ALWAYS state that manufacturer’s recommendations trump standards. And again – I know you don’t agree with it, so I would prefer not to have the same discussion – again – here on my website. There is nothing to be gained by it and it will help no one. You’re not going to change your stance and I won’t change mine. It’s similar to the whole modified-unmodified argument. People on one side or the other are unlikely to change their stance.
So I think I know what you may be getting at here – I am one of the people who recommend drywall behind kerdi per the manufacturer, as I recommend unmodified over it. I do tell people my opinions, but I also tell them the manufacturer’s opinions. People who come here for help are obviously utilizing due diligence in their construction method and can make that decision themselves. I will not turn this into the whole thread which has already been hashed to death on LinkedIn. Okay?
That said – great to see you! Thanks for stopping by.
Sorry Roger. Your right I had no idea you where the floor elf! LOL
I find so much bad advice online it’s refreshing to see someone else promoting proper shower construction. Keep up the good work!
JW
Love all your tips and your new book and especially your humor! 2 quick ?s. We are using hardibacker for our shower, walls then applying very bright blue waterproofing material before tiling. Do you but the liquid waterproofing material on the mud floor pan before tiling and do you install the hardibacker before or after the mud floor pan. We use the quick pitch and the curb and these are goof proof for the right pitch. THANKS SO MUCH FOR ALL YOUR AWESOME ADVICE
Hi Tricia,
It depends on how you are building and waterproofing your floor – you didn’t say.
If you are using the liquid waterproofing on your floor then yes, run the backer almost to the floor and build the mud deck right up against it. When you paint on your waterproofing it creates a seamless transition from wall to floor.
If you are using the traditional method with a pan liner on your floor then you leave the backer 1/8″ above your floor, fill that seam with silicone, paint your liquid from the wall, over the silicone, out onto the floor about three inches. If you bury the backer in the mud deck with a liner method water may reach the backerboard and begin to wick up the board. It’ll be wet behind your waterproofing. That’s no good.
Hi Folks:
Ugggh. I am reading this website as I will be tiling my shower…GREAT website…I had the shower stall constructed for readiness to tile – and then it’s my turn – We used a pre-fab redi-tile shower base, frame, and then Hardiebacker. I was advised to tape and waterproof seams only; however, after reading The Floor Elf’s article – I now see a 4 ml vapor barrier (plastic) should have been on been placed between boards and frame. Now what? Should I use the RedGard or have the guys take down the boards and add the barrier? Help! See why I started with “ugggh”? Thanks…Carolyn
Hi Carolyn,
You can either have them take it down and install a moisture barrier or use a topical membrane such as redgard or hydroban. Your shower needs to be waterproofed in some manner. The topical membrane would be much easier since the boards are already installed.
How much space should I leave between the floor tiles and the bottom row of wall tiles? The floor is already installed and grouted. Now I need to install the wall tiles. They’re going over hardi backer which is over a sheet of plastic on the studs. I’ve followed all your recommendations to date, but don’t know how much space to leave. The floor is 2×2 mosaic with approximately 1/8″ grout joints. The wall will be 12×12 with 3/16″ joints. If I can avoid caulking, I’d like to. It always seems to peel up and need re-doing eventually. The grout joints seem to last much longer. Thanks so much for your response.
Hey Gaylen,
Leave about a 1/16″ – 1/8″ gap and it does need to be caulked or siliconed. Silicone and caulk are not made to be permanent products – they are made to be replaced periodically. It’s just normal shower maintenance. With a proper bead of silicone, however, you should only need to do that every 5-7 years or so. Grout will eventually crack out of there. The different planes are going to move at different rates because of different substrates, as well as in different directions. Grout can not compensate for that movement – silicone will.
Thanks for your input. Unfortunately, it was exactly what I expected, except that all snide remarks were omitted. I think I’ll leave somewhere between 1/16 and 1/8 and grout with the same unsanded grout I used on the floor. Then I’ll apply a grout-color-matched caulk. Is that a good idea? It’s what I did in the other bathroom about a year ago which still looks quite good.
I’m getting ready to install a walk-in shower and a tub (both with tiled walls). We have a pre-fabbed base for the shower floor that will also be tiled.
I have a contractor friend who told me he attaches roofing ice and water shield membrane directly to the studs and then secures cement backerboard over the top of that. He did say that he does this because he’s generally paranoid about water getting in the walls.
Is there anything wrong with using this? Or is it just general overkill?
Also, how do I ensure that my waterproofing membrane “flows” into base and then the drain? Would I install the shower base, attach the membrane to the studs and then overlap it on the top edge of the base and secure/seal it with some silicone?
Since this is my first major foray into home renovation (completely remodeling our two bathrooms), I’ve generally adopted the mantra of over-engineering everything in order to make up for any minor mistakes I make. So I’m more than willing to go over and above to make sure it’s bulletproof.
What are your thoughts? Thanks!
Hi Erik,
You’ve mentioned two different things you’re tiling and no specific waterproofing method you’re using for your shower. I’m assuming you’re using the traditional waterproofing method on your walls?
The membrane goes down over the flange of the tub or base and the back of it is siliconed to the face of the flange. This ensures your wall is waterproof all the way into the tub or base. You can put the ice and water membrane over the studs, although it’s not necessary. If it helps you sleep at night, though, do it.
It won’t hurt anything.
Yes, I was planning to use the traditional waterproofing method.
Another side note, how far down do I bring my backerboard? Should it come just to the top of tub/base flange? Or should it actually come down over the flange to the top of the tub/base?
I did have another person suggest that I use the ice/water membrane on the studs, secure backerboard, and then redguard over the backerboard. But this seems to create the double-membrane issue you’ve described that traps moisture and creates mold. Glad I found your site and avoided this!
Thanks again!
You can either stop the backer at the top of the flange (the tile just hangs over the flange – it isn’t attached to anything – no thinset) or you can shim out the studs to allow the backer to run down over the face of the flange. Be sure to leave about 1/8″ between the tub and backer with either – the tub will expand and contract at a different rate than the wall as well as move when filled with water or people. You need space to compensate for that movement.
What about outside the shower?
As I prepare to install the plumbing in my gutted condo bathroom, I am planning ahead for the next phase – Wall coverings. In the shower area (where the tub was removed) I will be using cement board from floor to ceiling, as I plan on tiling the space from floor to ceiling as well.
But what about outside the “wet” area of the bathroom. For the areas outside the shower, the walls will be tiled half way up the wall (with bull nose top) and the top half painted. Can/should I use drywall from floor to ceiling? Something stronger on the lower half? I would believe that cement board only in the whole room would make it difficult to paint (not smooth enough). But I want something that is strong and will make a strong bond to the tile on the lower half of the wall (my tiles are 12 x 24)
Suggestions?
Hey Nick,
Regular drywall is just fine for any (wall) areas outside the shower, it’s plenty strong enough. You are concerned with shear force, you can’t slide the paper face off of the drywall by pulling on it, that’s how the weight of the tile affects the wall.
I built a master bathroom, and I used greenboard, used waterproof paint. I think I’m ready to tile. I’ve never had a problem before on client projects. Give me your opinion.
Hey Raymond,
Green board is not a proper substrate for an elastomeric membrane such as redgard (I assume that’s what you mean by ‘waterproof paint’). It may not have failed you in the past but it may in the future. I can’t guarantee failure – I can only give advice on methods guaranteed to succeed.
If using a liquid topical membrane it needs to be installed over cement backerboard.
I am installing a whirlpool tub and tiling the walls in a friends bathroom. The manufacturer’s directions for the tub required a 2×4 for support under the lip that runs around the top of the tub (on 3 sides), which resulted in the lip being 1/2 inch away from the studs. The tub is in a mortar bed, which has set.
Knowing the backer board had to go over the lip of the tub, and to solve the problem of the gap, I placed greenboard against the studs and covered every inch of it in 6 mil poly, which drips over the lip and into the tub. My plan is to put cement board over that.
I see that you don’t approve of this method, even with the waterproofing plastic. I am on a bit of a tight timeframe in finishing this project, and though I want to do it right, I’m concerned losing the time (and dwindling dollars) to pull the poly and greenboard, shim the studs, and re-poly the tub area. Can you help me understand why this is necessary, if the 6 mil poly creates a waterproof membrane? Thanks! ~Mark.
Hey Mark,
Temperature differential between the two sides of the wall may cause condensation to form on the backside of that plastic – the side with greenboard which disintegrates with moisture and grows mold. The poly does create a waterproof barrier – for the inside of the shower. The side with the greenboard is normally open into the wall cavity and any condensations can dissipate, not so with greenboard over it.
It may happen, it may not. I can’t guarantee it will. Every climate and house is different. I do, however, instruct people not to do it because if it isn’t there then I can guarantee it won’t happen. KnowWhatIMean? Just use your best judgement. You, apparently, are not someone that is a weekend warrior and hasn’t seen construction before, you know how it works. I trust ‘ya.