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 again Roger,
I’m up past my bedtime trying to figure out where to start my tile tomorrow morning (and wondering if I chose the right size tile…ugh). First, I’ve chosen a 6″ tile to match my 13″ floor tile. Now I’m wondering if I should use the 13″ in my tub/shower as well. It’s only 30″ deep, maybe a tad less if I decide to use a shower door. So there would only be 2 1/2 tiles on the sides. Will that look weird? I’m just wondering if the trend is to use the big ones in the shower, or if that’s all over and people are going back to small. I know it’s personal taste, but I don’t want to go with the size that’s least popular. Maybe you could share what your clients have been choosing. Maybe you could also tell me if shower doors are on the outs too. And if I do the shower door, how do I handle the tiles that will go from the top of the door to the ceiling? I have bullnose, but I don’t think that will be even with the door. Will that look odd if it sticks out a little over where the door frame ends?
Next, I’m wondering where is the best place to start the tiles. I could swear I saw you answer this question somewhere, but for the life of me can’t find it. I’ve watched videos that start the tile in the middle and work up, then down. Then I’ve read other sites that say to start at the bottom and work up. Most of them say to use mastic (which I know from you I shouldn’t), so I can’t really trust their instructions. Which way works better?
Thanks once again!
Hey Renea,
Most all of my showers, unless they are subway tiles, are normally larger format 12×12 or larger. I always draw a level line one tile up from the lowest level of the tub or shower base and tile the bottom row first. Once that is up everything else should remain level as you stack it.
The bullnose tile should stick out on the outside of the shower door. The shower door in my showers normally go directly up the grout line between the field tile and bullnose – almost the entire 3″ bullnose piece is outside the door. So no, it won’t look funny.
Not sure if this is -exactly- the right place for my question, but it’s to do w/substrates so here goes.
I’m finishing a downstairs bathroom which sits on an level, as-yet fracture-free 40 year old slab on grade. I’d like to use Suntouch heat mat in the portion of the floor fronting the vanity, toilet and shower. In this situation Suntouch recommends a thermal barrier above the slab, leading to final buildup of cork, their electric mat, thinset and finally tile.
Assuming I go ahead with this heat option, I plan on adding a vapor-barrier thickness of Redgard under the cork so as to avoid moisture infiltration from the slab.
I’d also like to avoid raising the finish level of the floor too far so as to avoid transition problems at the door threshold.
I’ve read a datasheet from a cork underlayment vendor recommending using tile not less than 4″ in an application including cork.
What I’m wondering is if pebble mat would be compatible with cork underlayment, which the cork vendor’s sheet implies probably won’t work. I’m also wondering if you have any opinions, tips or gotchas to relate regarding cork underlayment in general? Finally, any steer on whether 3/32nd or 1/8th cork are strongly preferred?
Now for a heaping trowel of rich flattery… your site is such a breath of fresh air when it comes to reading about tile in general. Entertaining, with comprehensive and highly specific advice, coupled with a lack of suffocating catholicism when it comes to picking components. -Some- sites seem to answer every situation with “Kerdi! Kerdi!, you absolutely must use Kerdi, plus a traditional membrane if at all possible!” While Floor Elf’s dog may burst into flames from time to time, Floor Elf is not dogmatic.
Hey Doug,
I’d use kerdi on that.
(Just trying to fit in).
I actually don’t see much advantage over a 1/32″ layer of cork as a thermal barrier unless you’re speaking of an area larger than about 300 square feet, short of that I wouldn’t think the 1/8″ cork would be much of a difference.
I would not use pebbles or pebble mats over cork. You need to look at the point load that a given product will place on the substrate. Although the pebbles have a rounded bottom and don’t necessarily come to a point, the total weight of any live load condense to a very high per-square-inch force. A woman in high heels actually has a higher point load than a corvette – another reason to get divorced and buy a hot-rod! (Just don’t tell my wife I said that). The recommendation to avoid smaller than 4″ tile comes down to the average point load the substrate can reasonably handle without failure. With pebbles or rounded stone the point-load increases exponentially. I would avoid those in that application.
The above paragraph would be about the extent of my tips or gotchas for cork underlayment – I honestly don’t use it that much. I do know with any substrate you should figure the dead-load as well as the live point-load that will be applied. That will let you know whether it is suitable long-term. I don’t think pebbles would be with cork.
Unless you cover it with kerdi.
J/K
Thanks for the kind words.
Thanks, and that exactly figures. Why nails work, come to think of it. I was sort of hoping you’d wave your magic elf wand and make it right.
In this case we’re looking at about 35-40 square feet of heat going into the slab. I’m pretty neurotic about this sort of thing but I think if I adjust my medication just right I’ll be able to forget about the little extra loss into the slab.
This is a guest bath anyway, so the heat won’t be on much. Come to think of it, I could put a coin slot on the thermostat and do ok, especially in the winter.
Thanks again, for your swift reply and your site!
Long story short, we brought in an expert tile man to re-do the floor of the shower that was improperly laid in our new walk-in shower (it sloped AWAY from the drain). He discovered that, contrary to the builder’s representations, there is NO waterproofing material behind the tile (travertine) wall. The builder is paying to fix it, but wants to have the wall re-done only to the extent of the bottom 12 or 18 inches, saying code doesn’t require waterproofed walls. But, it’s a high-end house and I’m not being limited by “code.” I want it done correctly. My tile man says that the waterproofing/vapor barrier needs to extend as high as the shower heads (there are 3 – it’s a big shower). Do you agree?
Hi Wayne,
Absolutely. Walls inside a shower need to be waterproofed at least up to the shower head by either a vapor or moisture barrier behind the substrate or a topical membrane on top of it. I bet there wasn’t a pre-slope beneath your liner either, was there?
It sounds like your tile guy knows what he’s doing – most would have simply fixed what they were brought in to fix and collect a check, he obviously cares about what he does – keep him around. 
dear roger,
two years ago we had our shower tiled. the last two months it leaked into my office, ruined a couple of my wood planks on the floor. the wall was also damp. my buddy came over and regrouted the whole shower with silicone. then the leak stop. it started up again, stopped then started up again. its driving us nuts!! we want to replace the wood on the floors, but need to get the shower fixed. what can we do?
thanks.
cindy.
Hi Cindy,
Your shower is leaking constantly, it is not an intermittent thing. Once enough water from that leak gets into the substrate it builds up enough pressure to begin to run out into your office. Once that pressure is negative on the shower side – your leak stops (into your office, anyway). Every time you use the shower it builds up more pressure (additional water leaks into the substrate) on the shower side until you reach a positive pressure point on that side – it begins to leak. That means when there is enough water on the shower side in the substrate to create more pressure than is on the office side it will leak. As it leaks it adds more water to the substrate until the weight (pressure) of that water is no longer held back by the wall. The only reason it is doing this rather than leaking constantly is that regrouting with silicone (???) SLOWED the leak – it did not stop it.
Unfortunately the only solution for a leaking shower is to tear it out and rebuild it. Leaks in a shower are due to a compromised waterproofing method in the substrate – behind the tile. It has nothing at all to do with the tile or grout. There is nothing you can put over tile and grout to make it waterproof again – your waterproofing is behind the tile. If it’s leaking that’s what needs to be repaired.
If you can pinpoint the source of the leak – exactly – you may be able to only remove the tile above or in front of that portion, repair the waterproofing, and re-install the tile. That, however, is a hit or miss deal. And it’s my experience that if a shower leaks in one area it does, or will, leak in another area. Most shower leaks, short of a blatant compromising of the substrate (think axe through the wall) are due to improper construction. Showers are not improperly constructed in one area of the substrate – the whole thing is usually incorrect. If it leaks in one spot it will likely leak in another eventually, if it isn’t already.
First off I love the whole consept of your website, it’s great and you seem like the kind of person I would kick it with.
Okay, I am planning on redoing my bathroom. There is some kind of fake marble looking particle board on the walls at the moment. The edges by the tub and around the fixtures is starting to become saturated and the board is falling apart in small brown pieces that must be cleaned out of the tub before you can use it, EVERY TIME you use it. I know it needs to come out and plan to tile the walls. I am a little nervous about what I might find under the board, how can I tell if the studs are damaged? If they are then what?
Keep in mind this is my very first remodel that included more than paint and replacing hardware. I am determinded to do it myself. I am really good at following directions just need a good website where they have step by step directions on how to do it all, from the water proofing to the grout and everything in between.
Hey Red – I’ll kick it with you.
Once you take down that fake marble looking garbage (it’s probably pressure-treated ply with a ‘waterproof’ covering – which isn’t waterproof) look at your studs. If there is any moisture in them you need to let them dry out a couple of days. There probably will be since it sounds like it’s all disintegrating on you. Once they dry out – poke ’em with your finger.
If they’re soft you need to replace them or install ‘sister studs’ next to them. Those are just replacement studs placed right next to the current ones without taking out the current ones. (My college English teacher just choked on her toungue!)
If they aren’t soft and there is no visible disintegration they are likely just fine. Just take your time. It’s easy – hell, I do it.
Hi Roger,
I have a problem with a tile installation. The tile has been installed, but there was no vapor barrier installed….so I have a leaking shower! I was wondering if there was a remedy for this issue by coming from the other side of the wall (where there is no tile). Cutting away drywall is much easier than ripping out tile. So, is it possible to use Redgard on the back of the backer board to create a vapor barrier? That would make things much easier.
Thanks a bunch!!!
Hi Jeff,
Unfortunately there is no way to waterproof from the backside of the wall. You can get the redgard on the back of the substrate itself but you won’t be able to get anything between the substrate and the studs. Water wicking into the studs is where most of the problem lies with a leaking shower – in the wall, anyway. The studs will also wick that water all the way to the floor and cause further damage.
Waterproofing on the backside of the substrate causes what is known as a ‘negative’ pressure barrier – basically the water you are trying to contain is pushing against an unsupported membrane (no substrate on the opposite side of the membrane from where the water is pushing) so even coating the backside of your substrate will fail eventually. You need a membrane with full support behind it to create a positive pressure barrier.
I got a lousy shower install job. I am trying to figure out what they did & what I can salvage. I have a pro recommended by the tile supplier that I used coming by later today to look at the situation, but I am also trying to educate myself to figure this out. (Installer was a sub, that I didn’t deal with directly.)
I am looking at a shower with a crooked wall, blotchy/light-colored grout, and a floor-to-ceiling corner crack, which is the leading-edge issue right now. The tile was installed in November, so far I have never turned on the water. At the contractor’s suggestion I purchased all the tile & the matching grout (TEC Accucolor XT) from recommended supplier so it was in hand when the job started. Because it’s a very small, tight bathroom I didn’t watch the tile sub that closely; they are the only sub that I didn’t know from prior jobs, and were introduced with high praise –haha. And I don’t know tile stuff.
So today I pulled the trim off the corner of the shower so I can see the shower wall in cross section & what I think I see is (in sequence) stud, greenboard, backer-board ( ? it’s gray), adhesive, tile (or grout).
Can’t tell about membrane/waterproofing or whatever. I don’t know what to think about the greenboard being in there, even tho the tile isn’t attached to it directly. I’m hoping that if there is proper waterproofing that it will be ok, but it just bothers me wondering why it is even there.
Also, the floor-to-ceiling crack occurred because a workman cranking up a fixture braced against the back wall and it popped, so I’m concerned about what effect this may have had on waterproofing at that joint.
I’m guessing the tile sub had a “handyman” doing the tile, and that he probably did not read the mixing instructions, & either didn’t dry-mix before doing a partial batch, got the mix wrong, or didn’t let it slake properly, or all of the above. (See, I’ve been trying to learn something after the fact ;-( ) This might account for the weird colors, but I also have to wonder about the integrity of the grout job, esp in that cracked corner.
Any comments/suggestions/advice about how to proceed?? (I’ll post what gets said by the new guy as well.) All of this stuff has been going on for months now & I just want to write the check to somebody competent to get it fixed & have some closure.
(And BTW I sure wish I had know before about Kerdi drain … grrr!)
Hi Ms. Pat,
Well, a couple of things going on there.
First, Accucolor XT is a fantastic grout that absolutely requires the directions to be followed. Not just the amount of water in the mix, but the slaking as well as the elapsed time for the different cleaning stages. If there is too much water added, or too much used when cleaning, it will lead to splotchy grout – what you have there. I’m sure it was done by someone with no experience using that specific grout. The inexperienced tend to work it like every other grout and it isn’t, it’s a different animal.
The cracked grout at the corner is also partly on the installer – any change of plane, per specifications, should be caulked or siliconed rather than grouted. Being that it ‘popped’ when someone braced against the back wall has me worried about the stability of the wall itself – it shouldn’t do that (but you already knew that). Regardless, the corner should be caulked, not grouted.
Without knowing how (or if) the shower was waterproofed I cannot begin to guess how or if that compromised the waterproofing in that corner. If properly waterproofed it shouldn’t have compromised it provided the crack or gap isn’t more than 1/4″ or so. So, on to the waterproofing question: I have no idea why in the hell anyone would have greenboard anywhere near a shower, let alone beneath a backerboard. The only warped frame of mind I could guess is that the installer believed that greenboard is waterproof (as it was initially advertised years ago) and considered that their moisture barrier. That’s a stretch, though, since anyone that would take the trouble to use a moisture barrier would not only use a proper one but would know that greenboard shouldn’t be near a shower. So I’m confused as to what you have there, or why it’s there.
I think your handyman theory is probably accurate – just enough information to be dangerous, as most of them are when it comes to shower construction. I would be most concerned with the lack of a visible moisture barrier or topical waterproofing – anything that waterproofs the shower. I have a feeling, as scary as it sounds, that the greenboard is there for your waterproofing. I would pull off the escutcheon (trim ring) from around the valve and look back in there for some sign of a proper waterproofing. Hopefully what you see there simply means the waterproofing was not run all the way to the corner (which it should have been) but it is still present behind the bulk of the shower walls.
Let me know what you find, I’m very, very curious now.
Nice stuff here. I learned alot. But why do you say Redgard is expensive? After looking at the Kerdi it looks like a good inexpensive option?And the backerboard with the vappor barrior methiod. I know the tiles aren’t water proof but in a shower how wet would the backerboard really get? $150 for the Redgard seems worth it to me but with the tile with acylic grout and Backerboard it should hold alot of moisture back? And why do I see all these houses with only painted dry wall on the ceiling? Should that be replace with the shower instal? Thankls
Mike
Hey Mike,
Cost is all relative.
Compared to kerdi yes, redgard is an inexpensive option. Compared to a faced topical membrane it’s a more expensive option. Compared to a moisture barrier and backerboard (which is not topical) – it’s a really expensive option.
The point isn’t necessarily how wet the backerboard will get with each shower. It’s more a point that the moisture will build up over time and is held into the backerboard. When you take another shower it will add more moisture to the backerboard. In a regularly used shower your backerboard will become fully saturated. When you take a shower the old water will flush through and be replaced with new. If the shower is not used everyday this build up will eventually be flushed out simply from gravity, but a regularly used shower gets a lot of water. Redgard is absolutely worth it – some people just think it’s really expensive for what it does. I don’t, in fact I use kerdi regularly.
Painted drywall on the ceiling is one of my pet peeves. But you’re correct, it is completely normal. They should at least have a very good ventilation fan. Ideally the ceiling should be tiled as well, I just can’t talk everyone into that.
What do I use when the joints meet with the Duraroc and blue drywall. Do I use the duraroc compound or regular drywall mud? The area I am most concern with is where the Duraroc meets the ceiling drywall, or the top corner.
Also if i use Kerdi do i need 6mil behind the sheet rock?
thanks for any help.
Lyndon
Lyndon
Hey Lyndon,
You can use regular thinset and an alkali-resistant mesh tape for those seams where the durock meets drywall. You can paint directly over it in any areas that the tile does not cover. If you are using kerdi you do not use a vapor barrier (6 mil plastic) behind the substrate – just one or the other.
Hi Roger,
Finally got my Kerdi up and I am ready to tile now. Just want your opinion on tile placement please. I have a a bath tub surround with the back wall having 58.5″ and the two end walls have 33″ of tile space. The tile I am using is 10″ wide so I am going to have to make some cuts and use partial tiles. The spacers are 1/8″. If I use the center line method I am going to have cut tiles on corners and outside edges. Should I put the cuts in the inside corners only or try to balance out somehow. You and your site have been a great deal of help and thanks a million.
Thanks,
Lyndon
Hey Lyndon,
Center your back wall and make cuts on both sides at the inside corners. On the side walls begin with a full tile at the outside corner of the tub and make your cuts on the inside corner against the other cuts. The installation will look balanced doing that since the cuts will ‘wrap’ around the inside corners and you have full tiles at both outside edges.
Roger
I was planning on using backer board only inside the shower tub area then the remaing bathroom I was going to use mositur resistant drywall to those areas outside the shower area but plan to install the tile 1/2 way up the wall around the entire perimeter of the room with a top tile border accent, before I tile I was going to apply redgard to all the walls to (backerbaord & drywall) then tile do you recomend I use backer borad to all the areas that are tiled? or can I just use it in wettest area the shower area?
Hey Bob,
As long as you have backerboard in your shower everything else will be fine. Backerboard is always a better option but as long as you only have the drywall in the dry areas it won’t be a problem.
Hi Roger,
OK, so I took my Hardibacker walls down, pulled down the barrier I had installed, and reinstalled the Hardibacker walls, cleverly using longer Durarock screws (2 1/4) than the original 1 5/8 I had used with the first install. So…now I Mesh fiberglass tape and thinset my backerboard seams right? I am a bit confused about Kerdi? Do I use this over Hardibacker/taped and thinset, before RedGard? Or do I just apply the RedGard to the taped/Thinsetted(?) Hardibacker? Also, when I apply the RedGard (and Kerdi?) do I apply it the corner seam where the wall meets the ceiling? Or just the corner seams where the walls come together?
Thanks so much,
I love your stuff, my kids always ask what I’m laughing at, hard to censor, so I just make something up.
Melissa
Hey Melissa,
Good call on the screws! (Never thought I’d type that unless it had something to do with last night’s bachelor party…)
Redgard and Kerdi are both topical membranes with which to waterproof your shower – only use one or the other, not both. If using redgard you need to tape and thinset your seams and, after cured, apply your redgard. Only apply the redgard in the corner seams where the walls meet the ceiling if you are tiling the ceiling. If you aren’t simply apply the redgard up to that point.
Sorry I’m hard to censor.
Just tell your kids you’re reading a story about a yak and a slide whistle.
Hi Roger,
Great website! I’m updating my tenant’s washroom while he is away and have a question for you regarding waterproofing. The guys ripped off the tile around the tub surround and under the tile there is a thin layer of plaster, then parched cement, then paster and lath, followed by wall studs. They removed the thin layer of plaster but have left everything else partly due to time constraints (we need to have the washroom done by the time the tenant comes back from vacation). They said they would put drywall compound 20 plaster over the parched cement to smooth it out then tile over it. I’m wondering if we should put Kerdi over the drywall compound 20 to waterproof? What would you suggest? The walls of the tub surround are interior walls.
Regards,
Jasper
Jasper
Hey Jasper,
You will need some sort of waterproofing behind that tile over the plaster. Kerdi would be the best, in my opinion, and you can also use liquid waterproofing such as redgard or hydroban. If you don’t waterproof it the plaster will eventually become compromised and begin to disintegrate, that’s no good.
we had contractors come in after house fire. Tile in the bathroom tub/shower was installed directly on Drywall. Can someone give me some information on what is supposed to be used under tile as regulation per Nevada Law. The tile job was very poor. Grout is coming out after only 3 months. Help please?!! I am sure this tile will not last…
Thank you.
Hey Deborah,
Unfortunately in most areas there is no ‘law’ pertaining to shower waterproofing. It’s either done correctly or it isn’t – no one ever checks and there are really no ramifications, short of a lawsuit, for the ‘contractors’ building them incorrectly. There are standards and guidelines for correct shower waterproofing via the TCNA handbook, but they are the standards for professionals and aren’t necessarily upheld by any commissions or laws. If it’s on drywall it’s done incorrectly – but you already knew that.
There are several correct ways to waterproof a shower. They are all described in my free ebook named, strangely enough, Choosing a waterproofing method for your shower.
You can get it here: Waterproof shower manual. Read through that and feel free to ask any questions you have at all.
Hi!
Thanks for answering my question under a different threat about using Mapegum…at your suggestion, we are planning to use the Kerdi membrane to waterproof over drywall that has been painted with latex paint (5 years old) before tiling our shower walls. A couple of questions for you…
– Do we need to do anything to prep the wall (since it’s painted) before applying the Kerdi membrance using mortar?
– Do you have a thread regarding putting up the Kerdi membrane? If no, any words of wisdom?
– To be sure we are on the right track, the drywall comes down right to the edge of the tub; we need to put up the membrane from where the tile starts high on the wall right down to the edge of the tub, correct? Then seal (do we leave a space for grout or use caulking?) along where the tile meets the edge of the tub?
– How do you deal with needing to have a hole dead centre in a tile for where the piping comes out of the wall…is there a way to drill the tile to make a hole? The last thing I want is to have it piece-mealed together.
Also, one more question…do I have to allow time for the mortar to dry between putting up the Kerdi membrane and putting up the tile? Nothing on the Schluter website and instruction pamphlet specifies. Thanks!
Me again…I went to the tile store today to discover that the product that the tile guy was talking about is actually Mapelastic HPG. Familiar with this? What I was told is that I can use it over the painted wall, need to prime over where the wall was just drywalled to put in the piping for the shower, must use fiberglass tape in the corners where the drywall meets and was taped and mudded and that the application will be successful and easier than Kerdi. My lack of belief in most people who work in sales positions made me feel checking with you might be my best option!
Hey Kathryn (again
)
Mapelastic is not recommended for drywall, it is only approved for concrete, masonry, cement board and engineer-approved, exterior-grade plywood – nothing else. You can read all about it here: Mapelastic HPG just click on the name of the product. Personally I wouldn’t use any liquid membrane on drywall, that’s just me, though. If you can find one that is approved for drywall it is easier, I just don’t trust it on drywall.
Hey Kathryn,
Nope – you can install your kerdi and tile immediately after. It’s one reason I use it.
You will need to rough up or sand down the painted surface so the thinset will grab. You cannot go directly over the latex paint.
I don’t yet have anything about kerdi specifically – it’s a specialized installation and it’s difficult to make short posts to cover everything. Just take your time – Schluter has installation videos and information on their site – you can check those out before you start.
Start the membrane at the horizontal surface at the top of the tub rail and go up. Use 100% silicone to seal the back side of the kerdi to the tub flange. Leave the tile 1/16″ above the tub and caulk that joint when you’re done.
They make diamond or carbide-tipped drill bits to make holes in your tile. I actually do have a post about that: How to drill a hole in tile.
Thank you so much for your help! Kerdi it is then! Hopefully that will be all the help we’ll need!
Would you use 100% silicone or urathane caulk in a new porcelain tile shower? Also i took your advice and scraped the Z flash idea reinstalled the hardi-backer on the walls. The hardi- backer rides 1/8 ” above rim of plastic shower pan 8mill plastic comes down over lip, now can i hang my bottom row of tile down 1″ to cover plastic? And will my thin set stick to it? I just don’t want my grout to fall out on my bottom row.
Thanks for all your help this site is AWSOME and a life saver!
Joe
Hey Joe,
You can use the urethane or the silicone – either one is fine. Get some silicone and use it to stick the backside of the plastic barrier to the flange of the tub. Your bottom row of tile can simply hang down over the flange – you don’t need to use thinset to stick it to anything – it can just hang over that gap and you can grout and caulk it as normal.
Thanks soo much for easing my mind and responding so quick!
I’m using kerdi in my shower, and schluter says never use anything but unmodified thin set. I am setting 12 by 12 marble tile. Do I have to use unmodified? Have you experience with latex modified thin set and kerdi?
Hi Jonathon,
Yes, I do it all the time. The modified works fine – you just need to give it an extra day or so to cure before grouting as the latex in the thinset requires air to dry. Please note that if you use modified it will void your warranty from Schluter.
I am tileing a shower, I put 1/2″ hardi-backer on 2×4 studs with 8mill plastic between. Do i also need redguard on walls before tileing? some sites say both and some say one or the other. will just plastic be enough with seams and corners taped and thin set? also do you recomend a Z-Flash between plastic shower pan and hardi-backer?
Thank You
Hey Joe,
You do not need redgard also. The plastic will work just fine. You also do not need the z-flash. As long as you have the plastic overlapped at the flange of the pan it will be fine. The water will run down the plastic and into the pan.
WOW! Thank you very much for responding so quickly! I guess the rest of the info I provided is OK so we’re going at it properly.
This is an amazing website! So MUCH information! And you do all this for FREE??! What gives? All I can say is thank you so much — in your own way, you are making a little difference in the world — helping so many faceless people!
God bless you!
You are very welcome Tina.
Thank you for the kind words.
Husband is re-tiling bath-shower. Grout failed on several tiles & he had to remove tiles exposing the hollow back (looks like green board!) He is planning to replace the backing & after cleaning the old tiles, grouting them back on. I’ve cleaned the tiles. He says the hardened stuff on the back of the old tiles must be removed too, but how? Using a coarse wire brush attached to a drill has not worked. Is there any way to dissolve it? Obviously we’re trying to save $ by doing it ourselves. The rest of the tiles are OK. At present we have a 3’x4′ open space where the tile was, exposing the back & can’t use shower, but can take bath. Need this resolved asap. Thank you for your kindness in helping us. -Tina
Hi Tina,
It depends on the type of adhesive on the tile. If it’s yellow you can heat it up with a heat gun to soften the adhesive and scrape it off. If it’s white you can soak it in water to soften it and scrape it off. If it’s gray you need to chip or sand it off. A vibrating sander with really coarse sandpaper will work.
The previous owner of our house took out the bathtub and put in a tiled shower. Water collects in the rubber membrane behind the shower wall . (One section is accessible through a door where you can access the plumbing and I can put my finger in the membrane and feel it collecting there.) We tried resealing the grout and it took the water level from coming up about 3 inches in the membrane to 1/2 inch but it is still there when we use that shower and it starts to stink. What is the cheapest/easiest way to fix this?
Hi Kris,
Unfortunately the only reason water would collect in there is the lack of a pre-slope beneath it. It sounds to me as if the liner is just setting flat on the floor beneath it. Through this door can you see the bottom of the liner? The outside of the bottom? See if it is sitting flat on the floor or if there is a deck mud (concrete) slope beneath it. If not (and I can nearly guarantee you there is not) any water below the weep holes never has any way to drain – it’s below the drain. And that’s why it stinks.
Sealer is not going to help. It will only slow the absorption of moisture into the tile and grout – never eliminate it. The fact that you slowed that down by sealing the tile may have, in fact, made the smell worse. It is no longer getting fresh water in there as much as it used to. Stagnant water is what is causing the smell – that derives from an improperly constructed shower floor which would drain all that water after each shower.
Unfortunately the cheapest/easiest fix would be to tear out the shower floor and rebuild it correctly. Sorry.
Rodger, I recently re-built a shower for my in-laws. Its a full tile (floor and walls) stand up shower (no bathtub) I did not leave a weep channel. Where is the best place to put on? Do I even need one? I’m assuming I can just go back and remove a little section of caulk from where the wall meets the floor? Another question I just thought of…. I tore out the old tile shower and rebuilt using hardibacker 6′ up the walls, my mother in law decided to add another run of tile to the top so the top 8″ is set directly onto the sheet-rock, above the shower head. Will this cause a problem. There is a moisture barrier behind the sheet-rock.
Thanks
John
Hey John,
If you have a tile floor you do not need weep holes at the change of plane between the walls and floor. Provided your waterproofing, whatever it is behind the walls, runs down and over the front of the membrane from the shower floor (which should run from the floor up the walls about 12″) any moisture getting back there will run down the wall and into the shower membrane and down into the drain. As long as everything is overlapped correctly you don’t need additional weep holes.
The tile on the sheet rock above the shower head will be fine – it’s not going to cause you any problems.
Can anyone tell me what to use to make plastic coated fiberboard in our mobile waterproof again? Around the top of the shower pan all the plastic has come off and the fiberboard is soaking up the water and starting to swell in those areas. Can i use acrylic enamel?? any help will be greatly appreciated. thank you dona
Hi Dona,
I’m sure someone could tell you how to do that – not me, though.
If you did find some way to make it water resistant again it would likely simply be a temporary solution. It apparently never was waterproof or it wouldn’t be doing what it is doing now. Acrylic enamel would end up washing away eventually. The easiest and cheapest way to correctly fix it would be to remove that fiberboard and replace it with something like sheet acrylic – the white, plastic-like material you see in showers. You can buy it in just plain sheets and cut them to size, put them up with construction adhesive, and silicone all the corners and to the pan.
Hello
I will be re-tiling a shower that has a tiled roof. how will i keep the tile in place while the adhesive dries?
Hi Michelle,
It will stay there all by itself. Just read my post about How to install tile on a ceiling.
Hope that helps.
Walk in shower, New construction. Read alot, confused. Can I plastic sheet vapor barrier, green board sheet rock, hardie board, acrilic thin set or mastic and ceramic tile. Pan, walls and ceil. Wife works at Lowes and being told a way. If I am wrong, what is the right way?Money is running out but want done right. Any Help Thanks, Terril
Also, I person that did tiling for friends put a vitchathan sheet pan seal in, grouted with thin set?, and put a black paint in vapor seal all over everything, thin set and tile. Is this right?
Hi Terril,
Wow, either someone at Lowes is trying to sell you guys a crapload of unneeded stuff or you are waaaaaaay overthinking this.
No green board, NO mastic, thinset does not need to be acrylic (unless by that you simply mean modified).
From the wall studs you want the vapor barrier, hardie board, modified thinset, then tile. That’s it. Really.
As far as the shower base or floor, go here: How to Create a Shower Floor For Tile and get a copy of my free ebook with instructions on how to create a shower floor. After you create that shower floor all you need above it is modified thinset and tile.
As far as ‘vitchathan’ I believe you mean bitchathane and the black paint vapor seal sounds like one of various roofing products, it sounds to me as if a roofer built a shower.
Bitchathane is not approved for shower floors – ever. It may last and it may not, I dunno. What I do know is that there are products made specifically for showers and they should be used. So to answer your question – no, it is not right. The only thing I have ever used bitchathane for in a shower is to waterproof studs behind wire lath on a mudded wall. Beyond that it really doesn’t belong in a shower at all.
All you need is plastic for your vapor barrier, hardi, screws, modified thinset, tile, the rubber membrane for the floor (in the ebook), sand, cement, and 2×4’s or bricks for your curb. That’s it, don’t let anyone tell you that you need any of the expensive crap or extra crap. My list of crap is enough crap to build a shower.
Hope that helps.
I have a leak coming out of my garage ceiling due to the bath/shower upstairs above it. I have isolated the leak to be caused by pointing the shower stream of water to a particular spot where the tub meets the cultured marble wall (the seam around the tub that is normally sealed with caulking). The spot is in the long side of the tub (i.e., not in the short side where the shower head is). However, the “leak” is coming down through the ceiling at a point a few inches past the edge of the tub on the short side where you stand/kneel to turn on the controls. My theory is that water gets into the seam in the long side (due to a caulk hole or caulk failure??) and because there is likely a lip on the tub, the water then flows around the tub along the tub lip down the long side … around the corner … down the short side … and finally (due to no kick-out) down to the floor and into the wall on the short side of the tub toward the toilet next to it. I am getting ready to re-caulk this seam between tub and marble wall. I have read a lot about leaving weep holes in this seam when the wall is made out of tile since tile is not waterproof and water needs to have a way to get back into the tub. My question is, what if the wall is essentially three pieces of cultured marble (two short side pieces, one long side piece)? Since marble is waterproof, water should not be getting back there … so should I just seal it tight where it meets the tub lip? I’ve read advice that says water getting into the weep hole should come right back out … but this is obviously not happening here (assuming my problem is a hole in caulking where I am spraying water into) … the water is trapped and running around the tub … what is supposed to “kick” the water back out into the tub via the weep holes? In my case, the water seems to run all the way around the tub lip the edge of the tub (i.e., where you kneel to turn on the water or bath your kids) and into the wall??
Hi Scott,
I think (and that’s all I can do since I can’t see your shower from here
) that what you are dealing with is a pressure issue in the flow of water along your tub flange. When water gets into the ONE (that part is important) hole in your seal along the tub, as the shower head forces more water into the hole, the water that is already behind your seal needs to make room for it. If the pressure being applied from the outside of the hole or break in your seal is greater than the pressure from behind, which it will be because there is no pressure from behind, the water will simply find the path of least resistance. In this case that would be the area that it is running down the wall on the short side of the tub.
Once it hits that opening on the short side of the tub and gravity takes over, rather than pressure, it takes much less pressure to force water along that path. You now have essentially a water path or ‘river’, if you will, behind your caulking between the caulk and tub flange. Since gravity is on one end it takes almost nothing to ‘pull’ water into that space now. The simple act of taking a shower will cause water to be ‘sucked’ into that space – but you know that because your garage ceiling is leaking.
There are a couple of things you should understand when dealing with cultured marble. Showers and tubs that have cultured marble installed in them are (99%) not waterproofed before the cultured marble is installed – the product itself is the waterproofing. Cultured ‘marble’ is a misnomer – one that irritates the shit out of me. Cultured marble IS NOT marble (and real marble is not waterproof). It is not natural. It is not even stone. It is what is known as an ‘engineered composite’. That is a man-made mix of different materials to create the component. In this case it is (usually) a mix of polyester resin (as the main component) and ground up marble dust (for coloring and to give it the look of marble.) For all intents and purposes cultured marble is a sheet of plastic. Given that – the only places it would not be waterproof are at the seams and along the edges (at the tub). All these spots need to be SILICONED (not caulked with acrylic) to make the installation waterproof.
You do not need weep holes in the silicone for cultured marble shower walls. You do need to regularly scrape out and replace the silicone with new silicone about every two years to maintain a water-tight installation. Your best course of action (short of replacing it with tile
) would be to remove all the silicone in the shower and resilicone the entire installation. This means all the seams and corners as well as the seam along the tub – entirely, no weep holes. Once you do that your leak should stop. If it does not you should have your shower valve pressure checked to ensure there is not a plumbing leak.
But I don’t think the plumbing is the problem. But I can’t see it from here.
Once you do that and the leak stops be sure to resilicone the shower every couple of years to prevent the same problem.
Hope that helps!
So I have a problem I think
some of this was done by my tile guy while I was gone.. so I’m hoping to keep from having to rip out the walls. I have a shower ready for tile.. the cement board is on the wall with 6 mil plastic behind it on the studs. There is also a niche with 2 coats of RedGard… the tile guy got a little zealous and started rubbing the Red Gard all over the shower… I think he managed to get only one coat. and it only extends up 3/4 of the walls. Will this cause a tile failure in the future since I also have plastic behind the cement board? Should I scrap off as much of the RedGard as I can on the walls? RedGard says it takes 2 coats to be “water proof”
Hey Travis,
You should be fine. The walls are not sealed up enough to create any trapped moisture between the Redgard and the plastic so you’re good to go. The only issue with plastic and a topical membrane is trapped moisture – you won’t have that problem. You can leave the Redgard as it is. Just make sure there is enough Redgard on the niche to make that waterproof.
Don’t panic, it’s just tile.