I get a LOT of questions from my readers about basic shower construction. I understand that my readers don’t consider this stuff basic and there’s no problem with that. The problem is that I end up answering the same questions over and over and over… So, to save what very little is left of my sanity (which is a number roughly equivalent to absolute zero) I will cover some basic things here so I can simply reply ‘read this’.
If you’ve been channeled to this page by one of my smart-ass comments please take no offense to it, I’m here to help. Please understand that I currently have over 12,000 comments (questions) on this site (seriously) which I’ve answered – every one of them. I’m just trying to make your life (mine) easier. I will continue to answer every question I’m asked, I’m just super cool like that. 
If, after reading through this, you still have questions feel free to ask them in the comments below.
You can also download my shower waterproofing manual which should answer a lot of questions and cover basic techniques and methods you may be confused about. Go ahead, it’s free. So without further ado (doesn’t even look like a word, does it?) let’s get on with it. (For all my readers who feel the need to correct me: I KNOW it’s actually ‘adieu’ – I was being facetious. Thanks. 
)
Leaks
First and foremost – tile is not waterproof. Grout is not waterproof. Adding sealer to your tile or stone will not make it waterproof. Your shower should be completely waterproof before a box of tile is even opened! No matter which waterproofing method you choose, proper substrate preparation is the only thing that will make your shower waterproof.
If you have a leak in your shower – stop using it immediately if at all possible. If that is not possible (it’s your only shower) have the shower repaired – immediately. If you see water leaking it is likely not nearly as much water as you don’t see leaking into your wall cavity and structural framing. By the time you ‘see’ most leaks the framing is normally already considerably compromised.
No, there is nothing you can put over your tile to make your shower waterproof if you have a leak – not even sealer. A tile or stone sealer is made to make your tile and grout stain-resistant, not waterproof. It does this by sealing the pores of the tile and stone to slow (NOT STOP) the absorption of liquid and prevent staining. It only means you have more time to clean up the spilled red wine cherry kool-aid before it stains anything.
Substrates
Drywall is not an acceptable substrate for your shower unless you are using Schluter Kerdi waterproofing membrane – that’s it. Cement backerboards are the standard and there are also other products such as waterproofed, gypsum based boards like Denshield and waterproofed, foam-based sheets like wedi or kerdi board.
Cement backerboards are not waterproof. They are water stable, which simply means that they will not swell or disintegrate when exposed to moisture or water – they won’t change size. But they are just like your driveway, they will soak in water, hold water, and dry out, just like your driveway when it rains. If using backerboards there needs to be a waterproof membrane utilized as well.
Membranes
If you are using a topical waterproofing membrane such as a liquid like redgard or hydroban, or a sheet like kerdi, do not use a moisture or vapor barrier behind your substrate. If you have a vapor or moisture barrier behind your substrate do not use a topical membrane on the front of it. This combination creates two waterproof barriers with your substrate sandwiched between them. any vapor or moisture trapped between them has absolutely no way to dissipate. This is lovingly referred to as a ‘mold sandwich’. It is not tasty. Use either a moisture or vapor barrier behind your substrate or a topical membrane on the face of it. One or the other – never both.
With that said, if you want to use a topical liquid such as redgard on the seams of your backerboard, after you tape and mud them, you can do so without problems. If your moisture barrier and backerboards are properly installed there is no real reason to do so – but if it will help you sleep at night go ahead and do it.
If you are using a topical membrane and you have an exterior wall with either plastic facing or kraft paper facing you need to cut slits into that facing before installing your substrate. If you do not it will create the aforementioned mold sandwich. Give moisture or vapor somewhere to dissipate.
Shower-tub transitions
There should be a gap between your tub or acrylic shower base and the bottom of your backerboard. If you are using a traditional barrier waterproofing method you do not need to do anything with this gap. Do not fill it with silicone! This will trap moisture running down your barrier and it will have nowhere to go. If you are using a topical method you can fill it with silicone if you want. If you are using liquid you should fill it with silicone. This creates a waterproof plane between your membrane and the tub or base so water or moisture ends up in the drain rather than in your wall.
When you tile you can tile right over that gap. You should not fill this gap with thinset behind the tile – it will crack due to movement. Your wall and tub or base will expand and contract at different rates – it will crack any cement-based product you place between the two. This includes thinset as well as grout. You do not need a solid backing behind your tile over this gap – it should be less than 1″ wide. You shouldn’t normally be walking on that tile in that particular spot. Yes, it can just hang there.
Grout
If your grout is cracking it is due to movement 99.9% of the time. Type ‘cracking’ into the search box up there and you’ll find in-depth explanations for your viewing pleasure.
If you have white, or lighter than normal grout when you’re finished grouting it may be efflorescence. This is mainly due to minerals in the water being left on the surface of the grout when the water evaporates. It is usually indicative of either incorrectly mixed grout or using too much water while cleaning the grout – not wringing out your sponge enough. This is normally only on the surface of your grout. Scratch the very top layer of your grout in an inconspicuous spot with your fingernail. If you have the correct, or at least a darker, color beneath the surface that is the likely cause. The easiest, quickest fix, provided it is only the very top layer, is to get some drywall sanding sponges and go over the grout lines very lightly. Just like burnt toast – scrape it to the color you like.
Corners and changes-of-plane
Caulk.
Disagree with me?
Like any other website I get my fair share of people who disagree with my methods or techniques – it really doesn’t bother me. I am more than willing to have a civilized, intelligent conversation about anything tile related. If, however, you simply attack me personally and act like an uncivilized ass I will call you on it – and not in a nice way. I write this blog in a particular manner, it does not mean that I take my profession lightly – I most certainly do not. If I wanted to be a pompous bastard I currently have 19 letters I can place after my name – all tile related. But I’m not a pompous bastard – you can just call me Roger.
If you are a contractor with a customer who has come here for information and I’ve told them you’re wrong – realize that the extent of my knowledge of that particular project is limited to what I’m told by your customer. It does not mean that I am ‘out to get you’ or anything of the sort. I normally limit my replies to those situations by stating the current TCNA and/or ANSI standards pertaining to what I’m told. If you disagree – please let me know in a civil manner, If you’re correct I’ll back it up – I do this everyday, too! If you’re an asshole about it expect the same in return (It’s the comment by ‘Kanela’ with the bold print before it) – and please have a thesaurus handy to interpret my reply – I’m a very well educated asshole.
That’s it for now. I will likely add to this post on a regular basis. If there is anything I’ve caused confusion with please, for the love of God, let me know. I can change this page since, you know, it’s my website and all. If you have any questions at all please ask them below – I’ll answer, really.
While planning an update for my daughters bathroom (straight out of the 70s, harvest gold EVERYTHING!) she told me the shower is leaking onto the floor. Just with a quick once-over, I found tiles and grout coming loose inside the shower, and a line of tiles coming off the front (outside) of the curb. When I pulled them back, there was moisture behind them.
So now the update will include a total shower rip-out-and-redo. I also found the previous owners must have tried some repairs in the past, noticing slightly pinker (less gold) tile in the bottom 1/3 of the walls. Ugh, call Guedo! 
Doing research for the shower, I stumbled here, and have been hooked. Thank you soooo much for all the great info and your fabulous sense of humor… I love it! So now I have a couple of questions for the Jedi Tile Master.
1. I’ve read your waterproofing guide, and I’ve decided to use the liquid topical on the walls and ceiling. I’m debating between the traditional floor pan or the liquid topical floor. With the liquid topical, do you still put the mud slope over it like you do in the traditional, or is it just preslope, liquid, then tile? I’ve found more info on traditional, but the liquid sounds easier with fewer steps. Which way would you suggest (so I know which of your manuals to get!)
2. The shower is in an alcove with walls on 3 sides. The current tile wraps around the corner and onto the drywall outside the shower like a picture frame, but I don’t like how that looks. I’d like a sleeker look with tile strictly inside the shower, ending at the corner. How would I do that transition from tile to wall at a corner so it would look finished without raw edges?
I’ll stop here for now, and I PROMISE I’ll use the reply for any other questions I think of! Thanks again for sharing all your knowledge!
Hi LL,
1. The liquid floor is just a single slope with the redgard, then the tile. I prefer the topical floors over the traditional, but either work just fine. The topical is easier, but you do need to have a topical drain. There is a method to do it with the regular drain which is included in my manual if you choose to go that route.
2. Most tile is available with the bullnose trim. It leaves a nice, clean transition.
Whattsa matter with gold tile???
I’m replacing my shower stall. The existing walls are tile, and I’ve bought fiberglass walls for the new shower. Can I glue the new fiberglass wall panels onto the existing tiles, or do the tiles have to be removed? The tiles go higher and wider than the existing shower, and I would like to keep this look, if possible.
Hey Jeff,
You may want to check with the manufacturer of the fiberglass walls. I know of no method where those are approved for use over tile. I, however, don’t install fiberglass shower walls – I tear them out.
Before I got online and researched how to do it, my husband had already installed a membrane/liner FLAT on the floor of our shower, then liquid nailed durarock to the studs (also added roofing nails). I have now informed him that a sloped mud bed was suppose to be installed UNDER the liner. So obviously, we cannot remove the liner because the sides were nailed to the studs which are now under the durarock. First I thought well, we can simply put the mudbed on top of the flat liner, then put redguard over it. However, I think I now understand that would make a “mold sandwich”?. What should I do now?
The only 2 options i can think of:
1.Will the durarock come off the studs without everything being destroyed?(He thinks it wont because of the liquid nails)
2.Or should we accept our losses and cut out the almost $100 worth of liner and glue? Then install a mud bed and apply redguard..
Do you hopefully have another solution?
Hi Leena,
You can cut your backerboard 2 feet above the floor (or however high your liner is) and remove that portion of the backer. You’ll need to replace that because it likely will not come out in one piece. At that point you can remove your liner and install the pre-slope, then your liner and replace the backer. You’ll only be spending what you need for maybe one piece of backerboard to replace what you removed.
You can not do the redgard – it requires a different drain as well as creating a mold sandwich.
ok thanks!
So am I understanding that using a topical liquid membrane requires a different kind of drain than a traditional pre-slope with a liner?
Yes. A topical drain has no weep holes in the lower portion. Your waterproofing goes over the top of it, if it had weep holes it would defeat the purpose.
Roger, thanks for sharing all this information. So far it’s helped me avoid a ton of mistakes. Unfortunately, I keep finding new mistakes I might make. This one is about pencil rail tiles. I’m nearly ready to install my 12″ x 12″ ceramic tiles with 1/8″ grout lines in my shower stall. I’ll include a mosaic accent strip with the pencil rail just above it. I have two questions:
1. Should I butt the pencil rails up against each other in a continuous line, or leave grout gaps that match my field tile?
2. Since the pencil rail sticks out from the field tile, I’m thinking this is a change of plane and I should have a 1/16 gap above and below it and caulk that with silicone – is that right?
3. Will the thin-set hold the pencil tile in place as it cures? Or should I tape each piece of it to the wall above?
Shoot – that’s three questions. Well, I think I mentioned I keep thinking of new mistakes to make.
If you have any other tips for installing pencil rail, I’d sure appreciate them.
Hi Jim,
1. You need a tiny space between them – minimum of about 1/32″ or so, but you don’t want to butt them.
2. No. The change of plane rule is where the substrate changes plane – it’s what will be moving in different directions. Tile or pencil rails on the same wall on the same change of plane will all move in the same direction at the same time. (How many times can YOU use the word same in the same sentence???)
3. Unless you have one of those huge pencil rails which sticks out more than 1/2 or so from the face of the field tile you shouldn’t need to tape it, thinset will hold it just fine.
4. …Shoot, there is no number four…
In an effort not to disappoint…
4. Do I try to grout in that teeny little 1/32″ gap between the pencil rails?
Thanks for the very quick, quite specific, and extremely helpful info. The explanation on #2 about the substrate is something I hadn’t run across and really helps with other decisions I’m likely to be making in future projects. (I knew, once I bought the tile saw, I was doomed).
Let me change #4. (I think the grout will work its way in). But I really need to understand clearly – I can’t just set the pencil rail on top of the mosaic tile, right? For the same reason I need a gap between the pencil rails, I need a small gap between it and the mosaic below and field tile above. Right? I doubt they make 1/32″ spacers, so I just eyeball that (sigh) – right?
4.2 (beta): You can have a regular grout line, or smaller, between the mosaic and pencil. The 1/32″ space is between the pencil rails themselves. They do make them, but you’ll lose ’em. (I do – they’re really small).
So, up the wall, mosaics, regular (or smaller) grout line, pencil rail with 1/32″ or larger between each one, then whatever you have above it. Let the thinset cure behind the pencil rail before you stack more tile on top of it.
4.1 (beta): yes.
If it’s any consolation once I bought a tile saw I was doomed as well…
Oh, jolly (from lots of chocolate milk) Floor Elf:
I’ve completed the shower up to and waiting for tile. (I’ll have to send you some pics). The Mark E. QuikPitch made the pan a breeze, and your help with the construction and the use of RedGuard made the rest a cinch.
Funny thing, though: I can build a shower with your help, but I can’t search a site for nothin’! I’ve tried to find the pages that mention substrate and didn’t find what I was looking for. There’s a song in there somewhere…
I’ve used Hardibacker for the shower walls and ceiling and the tub surround. Do I use regular sheetrock for the rest of the smallish bathroom, or greenboard?
Thanks for your help, again!
Hey Joel,
Either one works just fine. The rest of the room is considered a dry area, you can use nearly anything.
Awesome! Regular wallboard, at 2/3 the cost, it is! We are planning to tile the floors and walls clear up to the ceiling. Any special considerations for vapor barriers etc, in this circumstance? I know we need to make sure and use a good quality primer before painting the ceiling. Yeah, I’ve skipped that step in the past and found that the ceiling paint “bubbles” with hot showers… But anything else to consider? Thanks again, and rock on, mighty Elf!
Nope, everything else outside the shower can go directly to the drywall all the way around.
Roger, I am trying to set the toilet flange I hearing mount it on top of finish floor, flush with finish floor? not really sure what is right. Also I have been told to shim the flange with plywood to finish floor level an area just big enough for the flange to be secured? I know that to low can be delt with with shims and too high your screwed but I would like to do it right the first time. My main problem is figuring out the finish floor level. when I dry fit the backer board and tile I get 5/8″ but grout under both will raise that some? I am also putting nuheat custom mats they are very thin but they also thinset down and they say a skim coat on top can be done to make make it flat and easier to tile but its not necessary. they wont extend under the toilet but I would imagine I will need to feather out the edges a ways to make everything flat. your thoughts?
Hi GEM,
If you want it perfect then set your tile first then set your flange, the flange sits on top of the tile. Other than that set it at 3/4 and you’ll be fine. The heat mats will raise the entire floor, provided your floor is flat when you’re done. You can’t feather out a tile. You can feather out the substrate beneath it, but you’ll have incomplete coverage somewhere beneath the tile if you do that (provided your tile installation is flat).
Thanks for the quick answer and sorry I wasn’t clear I was talking about feathering out the substrate. When installing the mat I was wondering if I could feather out the edges of the areas where there wont be any mat verses putting a coat of thinset over the whole area where there isn’t any mat installed and again IF I do a skim coat on top of the mat prior to setting the tile. I understand the thinset when setting the tile has to be the same thickness everywhere in order to set the tile properly. The only reason I would do the skim coat is if I feel it is not flat enough for me after installing the mat prior to setting the tile. I was thinking I could feather the edge of the mat when I install it just like the seams in the backer board. I think the thinset will actually be thicker than the mat. the mat is about the thickness of a paper bag but stiffer and the wire is actually a little thicker. I am not sure it is even 1/8″ total by itself. Thanks again for all your help!!!
I would still set it at 3/4″, skim coat or not. I would skim coat the mat just to ensure a good bond, get the thinset into the mat really well to achieve a good base.
Can you PLEASE (!) post any follow up questions as a reply so I don’t have to search around for your previous questions. Thanks.
Thanks Roger! Sorry I didn’t know that was a link and now that I started looking to see what I was doing wrong…Clueless….I think I have seen you tell other people this and thought “glad that’s not me pissing him off” again….Clueless…. I also now see the ***PLEASE THIS READ FIRST!*** message I have gone by every time I post a question. Sorry I am such a Dolt……
Don’t wait so long to tell me to shape up if there is something else! It will save you a lot of frustration and I have thick skin so have at it. Again thanks for all your help and I will get straightened up….
Please help me!!! I live in South Africa so our walls are brick and mortar. My bath/shower unit leaks-badly. My bedroom wall on the other side looks like an Italian Fresco! The plumber told me that, yes, the water is leaking through my tiles and grout into the wall. We want to rip out the bath/shower combo and just put in a shower, but what must we do to our walls so that they are waterproof? I understand we will probably have to rip out the tiles where we want to put the new shower, but what do we put behind them and on the floor? Please help as the help I get here is….. well lets just say they believe tiles are waterproof here, and a silicone sealer over the grout fixes everything! I have a budget and don’t want to have to redo the shower when I am done. Thanks
Hi Marcelle,
Your best bet would be a product like redgard. I don’t know what you have available but an elastomeric membrane would be ideal for what you need.
Hi, I was told by the sales person at floor decor in Arvada that if I used the tile dr admix to my grout I would not need caulk in the corner seams of the shower , that the grout mix would be fine. What do you think ? Thanks you have been so much help. Betty
Hi Betty,
That is incorrect information. The admix is to prevent staining of the grout – you still need silicone in all changes of plane. If you grout them, even with the admix in it (which does not lend any flexibility to the cured grout), it will crack.
Thanks that is what I thought. I have a medium tan shade , non sanded grout for the walls. White silicone will look awful. Should I use clear ? Any other ideas?
If you google ‘laticrete latasil’ you’ll find 100% silicone that will match nearly any grout you have.
I just looked at that site I have emailed them and requested a printed color chart so I can get a sealant as close as possible to my tile and grout. The floor with the pebbles turn out great, now I am doing the shower and room walls with 4×4 ceramic. Thanks again, Betty
Hi again, This shower that I built for my granddaughter has a shelf the length of the shower , a seat/bench across the back of the shower and 3 cubbies for shampoo and stuff. That means there are a lot of areas that need silicone instead of grout. Can I silicone first then grout or do I have to grout first. I was just thinking that keeping grout out of all those planes will be difficult. Thanks again, Betty
Hi Betty,
You can silicone first then grout. It’s a lot easier in a situation like yours.
I received the color chart from Laticrete Latasil but their caulk is Arcylic not silcicone. Will that be a problem ? Thanks again. Betty
never mind the company that sent the chart answered my question. yes the latasil is silicone.
Okay.
They have silicone as well. The acrylic is just fine, the silicone is better. There should be a key on your chart, all the colors with triangles (I think) next to them also have matching silicone. They all have matching acrylics.
This shower/bathroom I am doing is for a teenage girl. I think the silicone will be best. Can’t get a perfect match but close… better than white. Betty
I am mixing the grout with the Tile Dr Admix 2 instead of water. I did it with the sanded for the floor now I am mixing with the nonsanded grout for the walls. Do I still need to seal the floor and the walls (grout seams) or does the admix 2 do that ? The guy at the store said the admix 2 would seal the grout but he also said I didn’t need caulk in the plane changes so I question what he said about sealing too. Thanks again. Betty
The admix seals it. No need to seal when using admix.
On outside corners where a bull nose meets another tile do I grout or Silicone ? Thanks
Hey Betty,
Grout works fine there.
Hi Me again. Well tile is done, grout is done tomorrow I silicone all the plane changes, Any helpful tricks for keeping a smooth caulk line ? do you tape or do you use alcohol with a finger or both ? Spray alcohol ? rag with alcohol or just dip you finger in alcohol ? Gotta get it good the first time. Thanks
Hi Me Again,
I lick it.
Just kidding. I use denatured alcohol in a spray bottle.
Hello! I realize this isn’t exactly what this section is about…But hey, I don’t know who to ask…so I recently tiled my shower with slate tile and has a white Jacuzzi Tru-level shower base with a honey comb pattern to make it slip resistant. I used stone sealant on the walls and didn’t realize it got on the shower base until the spots turned a brownish color. It’s all in the honey comb crap and looks filthy. I have scrubbed and scrubbed. Also I’ve used stuff that says it will remove clear coat..but used a tiny amount because I didn’t want to damage the base, it did nothing. Any suggestions? It makes me sad to look at it. Thanks!! Jessica
Hi Jessica,
I normally use a citrus stripper (Not Diamond from that joint down in Florida – a different citrus stripper…) to remove any mishaps with sealer products. I do, however, highly recommend that you contact the tech department from the company which manufactures the sealer and ask them what you should use or whether the particular stripper you have will harm anything. The acrylic in those pans are very durable and will not likely be affected by it, I’ve never seen it, but you need to put it on an inconspicuous place first to make sure of that before spreading it all over the floor of your shower.
Hey Roger in regards to your answer to Heidi’s question:
“You can tile one wall completely leaving about 1/8″ from the adjoining wall. When you install the wall up to it only leave about a 1/16″ gap then silicone that change of plane. If you leave a full grout line width the silicone bead becomes large and looks like hell.”
Would you do the same between the floor and the wall? Personally I was on the fence as to follow your advice on changes in plane since there is two very different camps on this subject, but I like this much better than a big silicone seam. how often should I expect to need to remove and replace this silicone seam?
Hey Gem,
Yes, I normally only have a 1/16″ gap between any materials I’ll be siliconing. The frequency of changing the silicone depends on a lot of factors including humidity (or lack of) as well as the amount of abrasion and use to which the installation is exposed. It’s normally not more than 2-3 years in showers and 5-7 years in dry areas.
This is awesome information. Thank you for the time and effort.
Actually, it is “ado” that would be correct in your 3rd paragraph. You can tell me to eff off and all.
Tell that to my French readers!
Hi Roger,
Back again. Have used this site off and on for 2 years and cannot say enough about the knowledge you give others. ( I don’t want to get too mushy but it is true).
Doing another project for a friend. They are thinking of putting in tub surround but have never done this and would like your advice on good waterproof product(surround) to use and is waterproofing method the same as tiling(durorock-redguard) and then surround and will that be placed over the lip. Totally different then tiling. Thank you in advance.
Paul M.
Hey Paul,
I don’t like surrounds, but I’m biased.
The surrounds themselves are waterproof when properly sealed with whatever sealant the particular manufacturer requires. Some surrounds are installed to the framing and some do require a substrate over the framing first. It just depends on which surround they choose. There is no need to waterproof it, as I said, the surrounds themselves are waterproof. Some require cement backerboard and some are fine with drywall. The different brands are installed in different manners in relation to the tub as well, so it’s difficult to give a general installation techniques.
I’m a lot of help, huh?
Everything is going to depend on the particular brand of surround they choose. I’d talk them into tile, but I’ve already mentioned the bias thing…
Thanks Roger. One more question.
I have tiled my own bathroom with your help and was very pleased. Without your assistance I would not have had confidence in installing proper water barrier.
I did have a tile man do the base (mud and liner) because I did not feel I could do it properly. I do have your manual on water proofing a shower and would love to try my daughter’s in a couple of months.
The kerdi method for whole shower appeals to me because you say it is best but still intimidated.
I have drywalled ,etc. but kerdi method for base and walls is different for a first timer who has tiled 2 baths but never used kerdi just hardi and vapor barrier on both.
Thanks,
Paul
Hey Paul,
It can be a bit intimidating but as long as you take your time and pay attention to detail there isn’t anything difficult about it, it’s just the unknown that’s difficult. You may also want to check into kerdi-board for the walls, I like it. A LOT! It’s how I’m starting to do most of my walls now.
Roger,
We installed a fiberglass base and then tiled our shower walls. We left the cement board short of the base, but overlapping the lip (vapor barrier etc. all there). When we measured for our tile though we ended up installing it flush to slightly below the cement board and now currently have a 3/8″ to 1/2″ gap. I’m not worried about the water so much as the goo (technical term) that can grow in there. Do you have any suggestions on whether or not to fill the gap? I’m just worried that the mildew and such will grow up behind the wall. Thanks!
Hey Kelli,
I would just silicone the gap between the back of the tile and the flange. No need to fill the entire gap – water will run out of it. As long as you have the bottom, back of the tile sealed to the lip then nothing will get up in there to grow.
Thanks for the quick response.
I am assuming from your response that the answer is no… but that means I shouldn’t fill the gap with the acrylic sanded caulk that matches my grout, or grout (knowing it would crack), as that will likely cause problems? I just know that there is mildew (or whatever the pink stuff is) on the ledge of the shower base that I need to clean with a toothbrush, and I would like to eliminate that if possible.
If that gap is open water will drain out of it. If you seal it up with any of the products mentioned it will trap water in there in some form, at least for a little while. You’re mildew problem will be bigger if you seal a 1/2″ gap.
Hi Roger.. great website, great tips!
Question: When installing durock around a tub, should the cement board cover the lip of the tub by a bit?
Thanks
Hey Keith,
If you can do it without the board butting out from the plane of the wall when it goes over the flange. To remedy that you can either shim out the backer along the studs or stop it directly above the lip of the flange. As long as your waterproofing overlaps the flange either way will work fine.
I always have the 6mil waterproof barrier covering the lip as well, and always shim the studs but obviously its more time and work. In a perfect world, which is the preferred or ‘right’ way?
Also should the waterproofing sheet be siliconed to the lip?
Thanks
I prefer shimming them out and going over the flange. However (!), as you know, that may create problems meeting up to the regular drywall in the rest of the room. The layout of the room and what you are butting against dictates it more than the ‘right’ way.
The back of your barrier should be siliconed to the front of the flange.
Roger, I like your mold sandwich comment. Actually I need your advice. I demo my bathroom and noticed some things. I need to know how to handle the remod. In my bathroom I have one wall that is a very uneven cinder block wall that had furring strips and batting insulation and drywall and then tile over that wall. It had about a inch of gap for the batting insulation. The other two walls were your typ 2×4 with drywall and no vapor barrier or insulation with tile. These two walls I am fine with how I am going to re-model as per your entry above, but how should I handle the first wall (cinder block) and avoid the mold sandwich. I don’t want the outside moisture coming in nor do I want the inside moisture going out. My materials are : 6mil plastic, dry lock, cement board, furring strips, kirdi, unmod thinset, screws, Dow 1.5″ thick solid insulation. This bathroom is upstairs. Its a brick home built in 1977.
Hey Mike,
You can use the drylock on the cinder blocks, install your furring strips and cement board, then kerdi. If you want or need insulation in that wall go ahead and use it, it won’t cause any problems. The space between the cinder block and kerdi will not cause a mold sandwich. Do not use the plastic if you’re using kerdi as your waterproofing.
I appreciate your answer. I didn’t see double barriers covered in my researching. Thanks.
Roger- I am getting ready to renovate my 27 year old bathroom and plan to use a pre-formed shower base to replace a 30×60 tub. The available space will alow me to use up to a 34×60 base and I am curious if you have found any particular units/models/manufacturers to be superior/better than others or any that I should avoid? Also do you prefer acrylic, fiberglass or other material. I just downloaded your Liquid Wall Waterproofiing and TT and am looking forward to reading both. Thanks!
Hey John,
If going with a preformed base they are all fairly comparable in my opinion. Unless you’re going with a pan that gets tile on it they are all the same (well, to me anyway…
). With any of them, whether they specify it or not, be sure to place thinset or concrete beneath it to fully support it.
A bit off topic, but couldn’t find a good page for this. What do you think of this product? (Link Removed)
I have some tiling experience (DIY) but am scared of preparing the bed. Seems like this might help, no?
EDIT: I have removed the link to the product. I do not endorse products I have not used and will not link to them on my site.
Hi JSM,
First of all I removed the link to the product. I do not link to products I have not personally used or that I feel are not beneficial to my readers. Please don’t take it personally, I don’t know who is actually asking for advice and who may be simply trying to spam free links from a reputable site. I’m sure you understand.
I have never used, nor spoken to anyone who has used, that particular device. It seems like a good idea, but it’s geared more toward someone who builds numerous showers. People who do that don’t need a device such as that in my opinion. The same thing can be accomplished (proper slope) with products such as Quick Pitch, which I have used, works very well and is likely MUCH cheaper for someone doing their own shower.
No problem thought maybe I missed something but then thought I had to much chocolate milk
and wanted to make sure. Have they changed it on the grout or is silicone still the standard there for changes in plane?
I do have a couple more questions.
1. As I previously mentioned my tile has wavy edges (I obviously don’t know what the hell they call this type of tile) and you told me how to keep them straight but what would be the smallest grout line or better yet spacers to use at the corners? I am using 18X18 on the floor and 6X6 on the shower wall?
2. On the outside corners bench edge, shower door edges etc.. if I lay the tile edge even with the surface how much of a grout line will the thinset for the bullnose give me? the tile box does not mention what size trowel to use. this would be the 6X6 porcelain. I could see this would be an easy screw up if I don’t figure this out first.
It’s still, and likely always will be, silicone at changes of plane in the tile.
1. I normally use 1/8″ spacers on those tiles.
2. It depends on the trowel size. Normally the installed height of the thinset will be 1/2 of the trowel size. If you use a 1/4″ trowel your finished height will be about 1/8″.
Roger, I am a little confused I see you told Heidi you recommend tape and mud in the corners for the backer board but in the topical book you recommend silicone did I miss something? I have siliconed my corners but I have not yet waterproofed and just want to do the best I can. should I pull it out and tape and mud?
Heidi has asked several different questions in several different threads here – her project is different than your project. If you have silicone in there then it’s fine. If you want to tape and mud them then there’s no need to remove the silicone, you can still do that.
I have recommended silicone here – a lot, and it is in the manual. The standards now dictate taping and mudding them, so I’m beginning to get away from that. Either way works, in my experience, but it may not work in all climates. So I now recommend taping and mudding all corners and am slowly moving towards that. The standards in this industry are changing every year, I keep up with them. Silicone does not, and has not to my knowledge, failed, but the standards dictate taping and mudding so I go by that where I can.
I know, I’ve confused the issue, I’m an unintentional jackass sometimes…
I would like to verify that I only use Caulk in the corners of the backerboard. I should use just Caulk, no tape?
Either silicone with no tape or tape and mud. Either way works. I recommend taping and mudding all corners.
A taping I go. Thank you
I am sorry I have several questions under different threads. I will be reading and come up with a question which I ask on that page. I will try to find this thread from now on.
I look forward to reading the new posts that come to my email every day. Many times my questions have been answered there. A few times I get confirmation on what I just completed. It has been great!
With all your invaluable help, I am now to the point of tiling. From the bare walls to the final mud bed, everything looks good per your instructions. I even impressed myself of how flat I got the final mud bed! (My husband is also impressed with the entire job so far!) I am using 13X13 porcelain tile. I plan to use a thinset and 1/8″ grout lines. I think I get the basics. My question is the corners/change of plane. I am not sure how to phrase my question. Do I meet the tile in the corner equally or can I install one wall completely to the corner and then have the grout line spacing on the side wall? If I can install one wall completely how much space do I leave between the tile and the perpendicular wall?
Hey Heidi,
You can tile one wall completely leaving about 1/8″ from the adjoining wall. When you install the wall up to it only leave about a 1/16″ gap then silicone that change of plane. If you leave a full grout line width the silicone bead becomes large and looks like hell.
Thank you. You know what I will be doing this weekend!
Okay my big head has been deflated!
I built the niche almost the width of the back wall of the shower. The plan was to build the height so that the finished grout lines of the niche will line up with the grout lines on the side walls using the full 13X13 tile. The back of the niche is to be tiled with the 13X13 tile. One side is good. The other side of the niche is about 1/4″ too low. The 2X4 that I used to build the niche is out of square. I have roofing felt underneath the 1/2″ Durock. The roofing felt is a continuous sheet along and around the niche. I attached the roofing felt to the 2X4 using Gardner Wet-R-Dri All Weather Plastic Roof Cement. (This worked great. After curing it would not pull off.) What is my best option here? Does thinset adhere to roofing felt? If yes, this will solve everything but I assume not. Therefore, I was thinking to reduce the thickness of the Durock, which I was able to do using the tile saw. Now of course, there is not enough Durock to hold the screws. May I use the Wet-R-Dri to attach the Durock to the roofing felt or should I use Liquid Nails Shower Adhesive or some other “glue”? Or should I do something else completely? Another thought is to cut the tile on the side walls so that the grout lines will line up. I would be cutting off about 1/4″, I think. What is my best and easiest option?
The top of the niche is not square.
Get a sheet of 1/4″ backerboard and use it for the top of your niche. The low side will be the correct thickness and the other side can be shimmed down to where you need it. And you can still screw it up there.
Thinset, liquid nails and wet-r-dri will all bond to the roofing felt, but you’re still bonding your substrate to a piece of paper – that won’t hold the tile. While you’re getting your 1/4″ backer you may want to pick up a level and a square while you’re there.
Just kidding.
Not really…
Thank you. I have those tools. I just didn’t use them properly! Lesson learned. As my father-in-law used to always say, “Measure twice; cut once”. I need to measure three or four times!
Roger,
In the process of a master bath redo and have a couple of quick questions….
Using a 12 x 24 porcelain tile for the walls and wondered if there was any general guidelines as to the notch size for the trowel. Does it correlate to the size of the tile?
Also, is there any generally accepted thickness for the substrate for the walls? The issue for me is having to shim the studs to allow the substrate to extend down over the shower base flange. This makes for an interesting join back to the old sheet rock at the top of the wall unless I use a thinner substrate.
Great information site and thanks for all your work and assistance.
Hey Dave,
I use a 5/16″ u-notch trowel for wall tile that size. It just depends on the flatness of the substrate and the quality of the tile. Whatever trowel will give you full coverage is the correct one.
Most wall substrates are 1/2″. Why are you going over the flange, that’s not really necessary. Although it’s preferred, if you can tie the waterproofing into the tub the substrate can stop right above the top of the flange and the tile just hangs over the face of it.
Roger what size trowel do you recommend for the thinset under the backer board on the floor?
It depends on how wavy your floor is. Normally a 3/16 x 3/16 or so works fine.
Thanks Roger, I have a 1/4 X 3/16 v-notch for the topical and its a new subfloor so no real issues, I’ll use that. Thanks for all the help!
yet another question, The doorway between the bath and bedroom.. I bought a metal strip to install with the tile which sort of caps the tile edge only to find out when I got home that the carpet in the bedroom has a metal edge glued to the concrete floor which is curved. What do I do at the doorway ? Help Please.
Remove the carpet strip, install the tile with the metal edge and put tack strip in front of it. The carpet will tuck between the tack strip and metal edging.
the carpet and the strip are glued to the concrete floor ? If I can get them up do I glue the tack strip ?
You can get tack strip with concrete nails in it. They are very short nails which drive right into the concrete.
Thanks I will try and get the old stuff up.
sorry 2 more questions, I finally got the old vinyl tile off the concrete floor and it looks and smells like they held some of them down with liquid nails . Still sticky, will that have any adverse chemical reactions with thinset ? Question 2, I bought floor tile at floor decor in Aurora I also bought Sanded grout with polymer, they said instead of mixing with water I should mix with “grout admix 2” and convinced me to buy it. Is that a mistake ? Thanks again, Betty
1. It should not have any chemical reaction with the thinset at all, but the thinset will not bond over it.
2. It is not a mistake at all, but it’s not necessary in my opinion. It does what it says it does (sealing the grout, etc.) but it makes the grout difficult to work with, especially for people who don’t work with it all the time.
so i guess I have to scrap the liquid nails off the concrete for the thinset to bond to the concrete ? How does the mix make the grout more difficult to work with ? I am using the pebble tile sheets on the floor to make a walk way from the shower to the sink. That is what my granddaughter wants. What problems can I expect ? Thanks again.
Yes, the liquid nails will need to be removed. The mix makes the grout stickier and more difficult to clean up. If you properly prepare the substrate you shouldn’t expect any problems.
The pebbles will use a LOT of grout.
I am scraping with a razor blade scraper to get the liquid nails up. The tiles around the edge of the floor are ceramic, the pebbles are just about 10 sq ft of a walkway from the shower to the sink. I am sealing the pebbles before I grout. I did get extra grout. How much do you think 10 sq ft of pebble tiles will use ?
Probably about a full 25lb. bag.
OK Help, I have spent hours scraping with a razor scraper, I have spent hours brushing with a wire brush, I have used a round wire brush on an electric drill. The concrete floor is still sealed by whatever the previous owners used. How do I get the concrete to bond with thinset ?
You can either use a grinder with a cup wheel (grinding or diamond, not wire) or use a chemical etcher. If the concrete was sealed you need to be more and more aggressive with it until you find what works. Not all concrete sealers give up so easily. I know, it’s a pain. You need to get the concrete to where it will soak in water when you splash it on there. If it just sits on top and beads up then the thinset won’t bond to it.
Hi I used a grinder today. It will take a lot longer to clean up the dust that is EVERYWHERE then it took to grind away the sealer. The floor now soaks up water.. Ye Ha
Hey Roger,
I’m sure you have answered this else where, but I haven’t found it yet. When I’m tiling I want to use spacers to keep my line even. I’ve seen some people leave them into the thinset and grout over them. And I’ve seen people stand them up on the tiles and remove them after. Which way is correct? And is it different for walls and floors?
There are spacers made specifically for leaving in the installation and grouting over. I don’t like them. Some people leave regular spacers in the installation and grout over them, they should be smacked with a board. Always remove your spacers, they compromise your grout.
Thanks Roger, that’s what I thought.