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.
Doug,
I have never written to any website like this before. I have managed apartment buildings for almost 40 years and now own and live in a 7 unit.
One of my apartments which I completely remodeled the bathroom on–the tile person floated the walls with cement. I have no idea if it was a membrane or what but he left a somewhat bigger gap where the tub meets the walls and he grouted it. I would not recommend his work again. I see now that silicone caulk is better so after 3 years and it was very stained from a tenant not ventilating the bathroom by opening the window–I had it completely dug out this evening. We removed the grout all around the tub, and up the corners.
The reason I had to do this was because after the last tenant left I was advised to just clean the grout and then use a textured caulk over that cracked and still dirty after scrubbing looking grout that would match the grout but was not silicone. The stains that I thought I had scrubbed away–I did not use bleach just natural cleaners–came back and bled through the textured caulk and the new tenants cried “Mold!” They are now gone for 4 days and I had the grout removed this evening and also the textured caulk that I had applied over the grout in a quick fix effort.
My questions are these and please if you can answer me soon as the worker is coming back in two days.
1. We dug out the grout around the tub–the gap is rather large like for sanded grout–can we just use a silicone caulk and does it need to be pushed back into the slot as far as it can go–or just a big bead that seals well on all sides of the area. I hope your understand what I am saying.
2. Because of the black mildew that we got almost 100% out anyway but we decided to spray some bleach into the cracks or gaps where the grout was. I am letting at least 35 hours go by before we seal it with silicone and I left the window open with a fan to circulate in the bathroom for the next day and a half.
3. Should I also rub the area with alcohol before caulking?
4. I used Snow White Custom grout before but I called Custom and they do not have a silicone to match and they sent me 2 tubes of their just on the market “bright white” silicone caluk. Do you know any brands of good quality silicone caulk that might be like snow white?
5. Can I caulk the edge in front of the bathtub where the tub hits the tiled floor? We scraped the grout down and there is an open crack there now–a thin very thin one –but I would like to know if the caulk can be used in the crack and then some on the grout that is staple that we did not scratch out?
6. Some of the grout lines or gaps again are large and is it okay to use this silicone to make sure it does not leak?
7. If some of the silicone caulk gets on the grout that is there I see where you say it sticks to anything so I am hoping it will look fresh and clean again around the tub anyway.
Most of my apartments are all caulked and we live in earth quake country so I am glad to hear it is the best way.
If you are not too busy and can get back to me as I am working again on this job on Friday morning.
Sincerely,
Lisa Olson
Santa Monica, CA
Who’s Doug? I’m Roger.
(I’ve been called worse)
1. As long as your silicone beads makes good contact at each edge it does not need to fill the gap all the way to the back. A better option would be to install some foam backer-rod and silicone over that.
2. The only thing that kills black mold is lack of moisture (and some very, very nasty chemicals you don’t want to play with). Bleach only makes it white – really. Just ensure the area is completely dry before closing it up.
3. You can rub it with alcohol to get it perfectly sterilized, it will give you a better bond with the silicone.
4. It is extremely difficult to cross-match manufacturer’s colors. There’s always going to be a variance. If what they sent you is 100% silicone it will be fine. Perfect, in fact, in every aspect except a shade difference. It’ll be the closest match you’re likely to find.
5. Silicone would work there, acrylic-based caulk would eventually dry out and shrink / crack. Silicone does not do that.
6. Yes, but a crack or gap in your tile installation should have nothing to do with a leak – ever. Proper waterproofing in a shower is installed and completed before tile is even touched.
7. Yes, it will be fine on the grout.
Thanks so much! I don’t think he’s totally convinced about the plywood, but to keep me happy he’s taking it off
It is sort of like wasting a whole weekend of work, but I’d rather fix the issue now and NOT when the tile is falling off/molding/etc.
Thanks again!
Yup, a weekend now saves weeks and money later. Easily resolved.
HELP! We are redoing our masterbath, (tub/shower combo side by side) and I have been doing a lot of reading, and have a couple questions.
1. For the shower, my husband decided to put whole sheets of 3/8 plywood to attached to the stud instead of fur strips. As we are using 1/4 inch Hardiboard as he is worried that leaning on the wall will make it bend and the grout will crack (for a variety of reasons, 1/2 is wouldn’t work.) Is 1/4 hardiboard strong enough to lean on/fall on and not bend the wall? It is attached to 16″ studs. Can we just use fur strips on studs instead of the whole plywood sheet? (it’s what I would prefer to do…)
2. He is uber worried about water seeping into the plywood (I’ve told him if we remove the plywood, this won’t be a problem…). He want to put redgard on the plywood, and on the backer board. From reading your site. I believe this will set up your “mold sandwich, no?
3. We’ve built a little ledge between the tub and the shower, really just for the shower glass to sit on. It will be tiled of course. So far, it’s 2×4’s and backerboard. I’m thinking I’ll redgard it, but do I put the thinset and mesh tape on first?
Lots of questions, sorry so long. Love my husband to death, but he will drive me to drink before this remodel is done!! (just so you know, in the house, he builds it, and I “finish” it.!)
Hi Mary,
1. Good God almighty – get rid of the plywood!
It’s plywood, it has no business inside a shower whatsoever. Ever. 1/2″ hardi attached to 16″ o.c. studs with tile installed over it WILL NOT MOVE! I guarantee it. I’ve tried to kick through them – I’m a 210 lb. former Marine (really) and I can’t KICK through it. It’s sturdy. Just shim out the studs, use 1/2″ hardi and tile it. If you don’t believe me, after you do that I’ll come over and try to kick through it. And you can laugh at me.
2. He should be uber worried – it’s plywood, it has no business inside a shower whatsoever. (did I mention that?) Yes, that will make you a fine mold sammich.
3. Yes, redgard it. No need to tape and mud unless you have seams on the same plane (middle of the wall).
Roger, I have a question about the point at which the cement backerboard nears the top of the tub. I understand I should leave a small (perhaps 1/8″ gap) between the bottom of the substrate and the top of the tub. Should the substrate overlap the tub lip which is 1″ tall? Or, should it stop short of the top of the lip and then have the tile be the only item that overlaps the lip?
Also, the tile shouldn’t touch the top of the tub, right? It should have a calked gap, right? The builder actually placed the tile on the top of the tub. This caused a movement problem when someone stood in the tub it pulled the tiles away from the wall.
I hope this is making sense.
Thanks
Hey Doug,
You can do it either way so long as your waterproofing barrier overlaps the flange (1″ lip). If you want the backer over the flange you’ll need to shim out the studs above it so it will sit flat from top to bottom, otherwise your wall will bow out at the bottom. Yes, there should be a gap at the bottom filled with silicone. That pulled the tile away from the wall or away from the tub? If it pulled them away from the tub just fill the tub with water and fill that gap with silicone, let it cure, then empty the tub. That will give you a complete seal.
Roger, yet another question. My son’s tub/shower was poorly installed by the builder. Water got into the back (5′ wide) wall and caused a bunch of mold and destroyed most of the cheap green drywall the builder used. As I started pulling down the tiles and the crumbling drywall (and molded insulation) of the wide back wall, I have determined that neither of the side (3′ wide) walls of the tub/shower are damaged. So, the question is, can I simply replace the whole wide back wall and leave the side walls alone? The thing that concerns me is the area where the walls join (at the corners). I haven’t figured out how I will be able to seam and seal the corners joints of the new cement board wall with the side wall drywall since the drywall and tiles are already in place on each side wall. I was planning on using the liquid topical method described in your most excellent how to manual.
Am I screwed? Do I have to replace both side walls?
Yes, I’m hoping for a cheap/easy way out (e.g., not having to do all three walls)!
Doug
Hey Doug,
Sorry, no easy way out of this one. Two main reasons: the side walls are likely built just like the back wall – which failed. And all that water that was continuously feeding the back wall? Once the back wall is properly waterproofed it’ll try to go somewhere else. It’s a good bet that it will go into the side walls rather than down the waterproof wall and into the tub. There is also no really good way to tie those walls to one another that will last long-term. Silicone may do it, but it also may not.
Hi,
My floor is flat but not level, it slopes away from the shower at about 3/8″ over 2′ (perpendicular to the drain). I don’t need the whole floor to be level, but do need it level under that shluter shower tray. What is the best way to fix this? Leveling compound? Deck mud? Any particular product that you recommend? Will need to apply this over plywood.
Thank you!
Hey Kios,
The best thing for that would likely be a leveling compound. Deck mud needs to be a minimum of 3/4″ thick, you can’t feather it out, it’ll crack. I prefer Laticrete products and their SLC is no exception – it’s good stuff. Whichever brand you use make sure to get the primer with it and install that on the plywood first.
Thanks for the info on the leveling compound, that did the trick! Will keep the dog off while it’s drying next time. No flames, but it was close!
Okay, I’m ready to tile the shower floor. Can’t believe I’m asking this question, but I’ve been putting off getting started since i’m just not sure. So tile has to be flat, but what happens around the drain? Shouldn’t the tiles slope towards it? I’ve installed a schluter drain which has quite a dip. I’ve watched the schluter video over and over, and it looks like the tiles are installed so that everything is level. Maybe I’m confusing flat and level?
Hope this makes sense, not sure it even does to me.
Hey Kios,
Will keep the dog off while it’s drying next time literally made me laugh my ass off – thanks.
Your shower floor will slope all the way from the perimeter of the shower to the drain. The schluter pan does this. As long as the bottom of it is level against your floor (you’ve done this – paw prints and all) then it will have the proper slope to the drain. If you place the pan down and look closely you will see it’s shaped like a very, very shallow bowl – that’s your slope. Since it is so shallow your tile will look flat, but it really isn’t, it follows the shape of the pan. If you get it installed and place a level on it you’ll notice that it is not level – it slopes toward the drain.
Hey Roger just wanted to write and say thanks. Because of your ceiling tile tips my dog did not burst into flames and i did not get hit in the head with falling tiles. I am now drinking a beer and getting ready for the wall tile.
Have another beer – those wall tiles aren’t goin’ anywhere.
Roger,
I have a multi question on 2 separate bathroom I’ve demoed (one 3 wall alcove tub & one walk-in shower). I am planning to use Kerdi for applications with standard drywall.
With the tub, the 3 walls happen to be exterior walls (2×4 studded) with fiberglass batt insulation with the paper vapor barrier facing inside. I hung up the drywall on all 3 walls including the ceiling. I planned to Kerdi all 3 walls and the ceiling to fully waterproof/vapor proof it. After watching Holmes on Holmes last night, Mike Holmes mentioned only Kerdi 1/2 up the wall (he was using durock with Kerdi) on the exterior walls as those exterior walls need to breathe which makes sense. So do you think I’m creating a moisture sandwich? Basically the construction from outside in is: cedar siding, felt paper, insulation with paper barrier, drywall, kerdi. Or am I overthinking this?
My other question is regarding the curb for the walk-in shower. I’m planning to use 3 stacked non pressure treated 2x4s screwed together as my curb. Again, I will use Kerdi. Since wood is not a recommended substrate for Kerdi, should I simply use liquid nails/screws to drywall around the wood curb for the Kerdi? Additionally, will thinset be sufficient to adhere the wood curb to the concrete subflloor? Or do I need to mechanically anchor the wood curb to the concrete?
Thanks Efl man!
Sam.
Hey Sam,
You aren’t overthinking it but you are not creating a moisture sandwich. Mike Holmes works in Canada, they have very strict building procedures regarding wrapping of the outside of the house walls. Due to the harsh weather up there they wrap them up like a birthday present before they put anything on them. So yes, up there they likely need to breathe. I never only kerdi 1/2 way up a wall and have never had problems. FULL DISCLOSURE: I always say that when guys that say they haven’t had problems that doesn’t mean it’s done correctly! So I will add this: I have also NEVER heard of problems with that from any other tile contractors. And I regularly talk to about 30 of them from all over the U.S. on a regular basis. So I don’t see a problem there. Now you have me overthinking it.
Regarding your curb. If it is on concrete you should not use wood. Wood will wick vapor from the concrete and eventually begin to warp or swell – just like pressure treated. Get some bricks (I prefer the gray concrete bricks without holes) and simply thinset them to the concrete to form your curb. You can then wrap kerdi right over the top of them.
Roger,
Thanks for the reply. Regarding using bricks to make the curb…great advice. I’m guessing to can simply use the thinset as “mortar”. Would using Ditra-set (dry set) to “glue” the bricks get your blessing? I figure I’d stack them 2 or 3 high (staggered pattern). Is there a recommended height of the curb?
On a different matter (if you don’t mind)….in building a shower niche (again Kerdi), the niche is built within the 2×4 studded walls with the back wall of the niche being the drywall of the outside wall (ie dining room). Hope that makes sense…I plan to thinset and Kerdi this back wall for the niche. The only foreseeable problem I see is if one needs to take down that dining room drywall, the back of the niche will go with it. Any thoughts Elfman?
Ah one more…if end up using a slab of granite for the top of my shower bench seat and the top of my curb (both sloped properly), how should the granite folks properly adhere the granite to the kerdi? Silicone? Also should the granite overhang slightly (how much) over the seat and curb OR be flush with the vertical walls of the bench seat/curb?
Again maybe I’m over thinking…..
Thank you for your service/consultation of Great Wisdom.
Sam.
Hey Sam,
Yes, you can use ditra set for the bricks. And yes on the staggered pattern.
I always put an additional layer of drywall or backerboard in the back of the niche. Both for that reason and the fact that most bullnose is 3″ wide rather than 3 1/2″. I helps it line up with the front rather than slivers.
Granite can be installed with ditra set as well. I would not install it to kerdi with silicone, it would likely come loose eventually.
Hi!
) The wall tiles from the shower continue around the bathroom 2/3 of the way up the wall. I’ve read it’s a good idea to go with CBU (although it may be overkill), so am planning to go that route. My question is regarding mortar. Willl use ditraset where there is kerdi, but will I need to switch to a modified thinset for where there isn’t kerdi? If so, what happens where the tiles overlap kerdi and cbu?
Before diving in to a new project, I’d be delighted to get some input on a bathroom renovation. No clue how to do a mud pan, so went with the kerdi/shluter setup (besides, saying Shluter Shower Shystem makes me feel like I’ve had a few drinks
Also a second question, regarding the post below, would silicone still be used for kerdi or do I need to get kerdi fix (or similar)?
“Do the back wall from edge to edge leaving about 1/16″ – 1/8″ then butt the side walls to it leaving about 1/16″ gap, then use silicone in that gap”.
Thanks a million!
Hi Cat,
No need to switch thinsets – you can use ditra-set for everything else as well. And silicone would still be used for those changes of plane.
Hi,
Thanks for your time, really appreciate your input. So I demo-ed the floor, which consisted of vinyl, 2 layers of linoleum, mosaic tile, 2 inches of concrete, tar paper and floor boards so rotted that I’m surprised that no one has taken a one-way toilet ride to the basement (aka Midnight Express).
Will replace the planks and lay down a layer of – 5/8 plywood? 1/2″ cement board? Is there a preferred substrate for kerdi/ditra? All the literature says that the substrate must be properly installed but not finding any info on how to go about that. How much of a gap is needed between plywood or cement sheets, and around edges? I’m guessing 1/8″ inch.
Thanks again!
Hey Cat,
Sounds like you had a couple of layers there.
You actually don’t need to replace the planks. If you are down to the floor joists all you need on top of them is a total of two layers of plywood totaling a minimum of 1 1/8″. I usually use one layer of 3/4″ and a layer of 1/2″ for a total of 1 1/4″. Your ditra can be attached directly to the plywood. You need a 1/8″ gap around the perimeter and between the sheets. The top layer needs to be offset (the seams) from the bottom layer and only screwed into the bottom layer. In other words – don’t screw the top layer of plywood into the joists – only into the bottom layer of plywood. That will give you a nice, properly built solid substrate for your tile installation.
Great thank you! My new favorite toy is a hammer drill
Need to replace some joists too, it”s been a messy job but that’s part of the fun.
Speaking of messy, here’s my quandary – would love to take my time with the tiling, but we have only one shower/bath. So here comes a stupid question: since I’m kerdi-ing (is that a word?) everything, can the shower be used before tiling and grouting are finished? Would be great to take a week or so to get every tile just right, but lugging and cutting tile on a hot humid day and lack of bathing could get unpleasant fast. I don’t quite fit in the kitchen sink!
Hey Cat,
Not really a good idea. The kerdi is indeed completely waterproof but there are a couple of problems you may run into. The biggest being soaps and shampoos negatively affecting the bond of the thinset in the seams. Also the abrasion of the water against the thinset may wear it away and compromise your seam. Maybe a bigger kitchen sink?
Hi there!
Ah I knew that would be too easy. Yes, I need a much bigger sink since there’s no room for my ducky!
Back to the age-old, tired question about thinset. Just to be sure I’ve got this correct: use modified thinset between wood and ditra as well as between wood and schluter shower pan, and unmodified thin between tile and ditra/kerdi. Makes my head hurt, time for a beer.
I’m looking for a good modified thinset and many seem to recommend Versabond, but since it’s only slightly modified, should something else be used?
Also, I have a big, old stupid vinyl window smack in the middle of the shower. The bathroom is on the first floor and faces the street (what were they thinking
); and yes I can see who’s at the front door while in the shower – but that’s another story. What is the best way to attach kerdi to the wood framing and vinyl?
Thanks a bunch, you’re the coolest tile elf ever!
Hey Cat,
You’re correct, modified below, unmodified above. Versabond is fine for most applications – that being one. If you want a better one mapei’s ultraflex II is good as well as Laticrete’s 253 Gold. Dunno what’s readily available around you. Use kerdi-fix or silicone to attach the kerdi to the framing and window sill.
Your guidance on this blog has helped tremendously as I have progressed through my shower tiling job. As I start tiling the back wall first I plan on using a shim of about 1/8″ between the tile and the shower pan. Should the gap be larger and, secondly, should I caulk the gap of the tile overhang and the pan? Thank you.
I should add that my 4 mil plastic overhangs the pan lip and that my concrete board siits obviously over the plastic and on top of the pan lip. The plastic is held in place to the pan lip with a bead of silicone so that it doesn’t walk anywhere, like behind the pan lip. I want any moisture to roll into the pan.
Hey Charles,
1/8″ is fine. Caulk around that gap leaving weep holes in the caulk line in a couple of spots so that water behind isn’t trapped there and has someplace to run into the tub.
Roger: Perhaps you can help me with my dilemma. Damn. In placing the shower valve escutcheon over the tile I see that it requiires two holes for the screws to fasten to the valve assembly itself, which is now behind the concrete backerboard. Damn. Okay, so now, it seems to me that I need to get a carbide tile bit and drill through the ceramic tile and the concrete board. Place some tape over the tile and drill? Damn.
Or…since the screw holes are only like 1/4″ from the 1 3/8″ hole for the valve, perhaps I can use my Dremel tile cutter biy and just notch the tile and finish the job with a masonary bit to drill through the concrete board???? Ya know, I was sooo damn proud of the nice hole I made for the valve assembly. Clearly a lack of forsight on my part.
Or a dremel. That will work too. It will also cut through the backerboard.
Hey Charles,
Damn.
A tile bit will work just fine for that. You can place tape over the tile to make your marks and get them in the right spot. No need to put tape on your drill unless it’s falling apart.
If you happen to own a roto-zip it’s perfect for this type of situation.
Not that I would know anything about that.
Damn.
The dremel tool bit worked great in creating the notch in the tile and concret board to access the screw holes. Jeez. Now, last question…for this project anyway. My wife picked out a trim for the shower that contains small rectangles of a variety of materials, including stone and glass. Can I use sanded grout on the glass? I am wondering if the glass will scratch no matter how careful I am. The gap between pieces is about 1/16″. Finally, thank you for all of your help on this site. You are now added to my favorites. Don’t you feel special now?
Hey Charles,
I use sanded grout on glass all the time without problems. It’s always best to test a piece first to make sure it won’t scratch, but it actually rarely does. With the glass and grouts I use anyway. You should be fine.
And yes, I do feel special now! (But not because of that, I just cracked open a fresh six-pack!)
Hi Roger, thanks for answering yesterday’s question so quickly. Your site ROCKS!
Now, for a dumb question…
How do I do the corners of my tub with the tiles? Do I apply tiles along the long wall from edge to edge and then have the perpendicular side walls overlap the tiles on the long wall (butt up against them)?
Or, do I space the tiles at each of the corners so that they create an even 90 degree angle to each other? This would leave a tinly seam of empty space behind the two corners of the three walls.
I hope I’m making sense in this question.
Doug
Hey Doug,
Do the back wall from edge to edge leaving about 1/16″ – 1/8″ then butt the side walls to it leaving about 1/16″ gap, then use silicone in that gap.
Thanks, that’s exactly what I needed to know!
Doug
Roger,
My bathroom tub runs alongsidfe an outer wall of my home. The tile leaked and I ended up with tons of water behind my shower for God knows how long = mold = stinky. So, I’m about to replace it all (the builder used that green dry wall crap and it toally disintegrated).
My question concerns the insulation I have to replace between the studs. It appears that the builder didn’t use faced insulation. If I use faced insulation it won’t cause a problem will it?
Doug
Hey Doug,
Not unless you are using a topical membrane such as kerdi or redgard to waterproof your shower. In those cases, if you do use a faced insulation with a topical membrane you want to cut slits in the face paper to allow trapped moisture to dissipate. Other than that – no problems at all.
OK, so I’m planning on (from out to in):
1) faced insulation with slits
2) cement board
3) redgard
That works, right?
Doug
That works perfectly. Read through my redgard post if you haven’t already and it will explain how to prepare a ‘primer’ of sorts so you don’t use as much redgard and get a good bond to the backerboard. It’s here: http://floorelf.com/installing-redgard-on-shower-walls-for-tile
I’m finally ready for the last step in our tile job…caulking, and of course I need some advice. I did one corner from floor to ceiling and just don’t like it. It’s not that it’s messy, it’s that the only brown color in 100% silicone is too dark. Now I can live with it if I have to, but I did use Spectralock and was wondering how risky that would be to use where the walls meet (not around the tub). It’s a 100 year old house, the bathroom is about 20-30 years old. So no new settling, but I know that the studs will expand and contract seasonally. The silicone wouldn’t bother me so much if it was a skinnier line, but I had some wider gaps to fill.
And speaking of wider gaps, I unfortunately made a huge goof around the tub. We started one row from the bottom, so when we put the bottom row in, I had miscalculated and have about 1/2″ gap between tub and tile…UGH! I don’t know if it will work to try to cram in some grout and get it to stick to the tile but leave a small space beneath for caulk. I hate to think of putting all that white caulk there that will look a mess in a matter of weeks. Any advice?
Other than those imperfections, I’m pretty happy with how it came out. Thanks soooo much for mentioning spectralock all over your site. I was terrified to use it, thinking it would be so hard. But it came out a million times nicer looking than the junk Home Depot stuff I used on the floors. Wish I had been braver to try it first!
Hey Renea,
You CAN use spectralock in the corners if you want – I simply don’t know how much your shower is gonna move. I can’t see it from here.
That determination is only one I could make looking at an installation in person. It’s up to you, and goes against the specs, but it can be done. Another option: did you know Laticrete makes 100% silicone which matches all their grouts? It’s called latasil and can be ordered over the internet. It may even be available to you locally. Google it.
If you place a solid spacer, like a 1/8″ plastic strip, under the bottom row of tile you can use spectralock to pack that space, then you’ll need to time the firmness correctly, but you can pull that strip out when the grout stiffens enough, but before it cures too much, then silicone the small gap you left with the plastic strip. The spectralock will stay provided you pack it in there.
I told you there wasn’t anything to be skeered of.
I love spectralock!
Here you go Renea, this is where I order it when my supplier is slacking: Laticrete Latasil 100% Silicone
very comprehensive info here roger. thanx for doing it. my question has probably been answered, but if it has i cant find it. Ive been working on retileing the master bath for TWO YEARS! im an awful procrastinator. but now im in the home stretch. ALL the tile is up, flaws and all. it looks a little crumby, but im moving ahead. on my grout bucket it says “wait 24 to 48 hours after tile install BEFORE installing grout.” not to be a pain, but my weekend ends day after tomarrow. can i go ahead with grouting less than 24 hours W/O disaster? or shld i just do what it says? also can silicone be used for poor cuts and gaps in upper corner tiles? or rip ’em down and find some wierd corner piece?
Hey Jamo,
As long as you used thinset (powdered in a bag you mix with water) and not any type of pre-mixed mastic then yes, you can grout it now and your dog won’t burst into flames. Silicone would be the better option for your corners and gaps if need be. As long as you’re only talking about a MAXIMUM of about 1/4″ (and even that is huge) then silicone can fill it without a problem. It probably won’t look spectacular – but after two years who’s gonna say anything, eh?
i got fed up w/ the powdered stuff and got a bucket. ive still got a huge bucket of dried stuff i cldnt use. and some gaps are definately bigger than 1/4 in. but w/o splitting hairs its been 24 hrs now and ill just have to cut the silicone tube small eh? ive got to finish this one so i can do the other one. wall is wet and falling out. thanx again.
Sorry about the spelling. No real excuse except rushing. Thanks
Hey Dick,
You do not need the cement (thinset) thicker over your tape. As long as you have the tape embedded in the backer it’s fine. You need to be concerned with flat rather than coverage when taping seams.
Peel those tiles off of the mesh and cut them individually. The glue that holds them on the mesh is normally water-soluble and the individual tiles make it difficult on a saw if you aren’t used to it. You can peel them off and cut them one at a time.
Hi Roger,
Just beginning to tape joints on hardibacker. When dry I can still see tape. Should I put on cement thicker? I am then going to put redguard on seams only because I do have a vapor barrier. Also.what is the best way to take off 1/4 of an inch on 2×2 small tiles on shower floor. With mesh is difficult. Using wet saw. Thank you again
Dick
Hi Mr. Elf,
I finished my marble job with ditra over plywood and I’m quite please with the results…even though it is not perfectly flush like on your pictures, not too bad for a diy’er.
I’m getting ready to tackle my shower, and am currently in demo phase…That durock + thinset + porcelain that was used is sure hard to get rid of…
I’m planning on using the entire schluter ”kit” including the kerdi board, , the shower pan and drain, kerdi fix…kerdi band and kurdi shoes, gloves and cap.
What is your view on kerdi board? And what about using the whole schluter kit. My main objective is to minimize the amount of sh** and f*** that come out of my mouth during the installation AND during the next few years!!!!
Hey William,
Love the kerdi board (except for the price), great stuff! I am not fond of the pans at all. They are installed all the time and I haven’t heard of any proper installations failing – ever. So they do hold up. But I’m an ass like that and prefer an old-fashion mud deck for all my showers. Nothing wrong with it, though. If you do use the pan and curb DO NOT kneel down on the curb or any part of the pan before the tile is installed and cured. The bare pan does not tolerate point loads (like your knee) well and will compress. After tile is installed, however, you can LITERALLY drive a forklift on it.
Seriously – I’ve seen it.
It’s a great system, you just need to take your time and follow all the directions. Don’t be worried about the words that fly out of your mouth during installation as long as when you are finished with the installation that no longer happens.
Hi ROGER
The other day I wrote to you and mentioned that I screwed hardiboard into the CPE liner on wall of shower 1 inch from the mudd job floor. You said to take it out and seal the pin hole but did not mention with what type of sealant.
Do I need to get the noble sealant for 30 dollars or is there a cheaper way out like silicone., tire patch substance or plumbers goop. Waiting till I get an answer from you. I respect your opinion with all tile questions and will not just put in anything until I hear your suggestion. Thanks for all info.
Dick
Hey Dick,
100% silicone will work as will a 2″ square patch of the same material your liner is made from. Either one will be fine.
Thank you, Roger. I used noble 150 in a tube with patch from material taken from folded corner. Seemed to dry well and seems fine
Dick.
I was told if you use Porcelain tile and epoxy grout. Since it’s impervious tile .05% and the grout is the same. Water won’t get though? s that correct? How much water would 0.5% be?? Thanks
Mike
Hey Mike,
Yes, true porcelain and epoxy will allow less than .05% penetration. How much would that be? Well, that would depend on the amount of water the tile is subjected to. Take that number, then divide it by .05%.
Thanks. There is wonder board and laticrete hydro-ban. But the bottom or top of the tub the weep holes weren’t installed. Should I still put them tre by digging out the sanded chalk? Or do you think it won’t have much water penetration to worry about?? TIA
You should be fine as it is. If you notice the tile or dark getting darker toward the bottom of your shower, an indication of water retention in that area, then go ahead and dig out some weep holes.
Hi Roger,
Installing hardi but went too low and put a screw into CPE liner on wall(1 inch from floor). Am I screwed or will I be okay? Last piece of hardi and was ready to tile. Is it necessary to take off board and seal where screw went?
Thanks,
Dick
Yes, you need to remove it and seal the puncture. The liner must be intact up to three inches above the top of the curb. Anything below the curb definitely needs to be sealed.
I am taking the board down and should seal it with what product? Was ready to tile and feel what next. should I worry about plastic behind the hardi that has screw holes in it.
Thank you again.
Don’t worry about the plastic. Ideally you should patch the hole with a 2″ square of the liner attached with the proper adhesive (pvc or cpe). In a pinch you can use 100% silicone.
Hi Roger,
I am putting up hardi backer but was wondering if the plastic behind it is seperated on all 3 sides not continuous because I had to take out 2 sides of plastic due to wall not being level. I already have hardiboard on furthest wall but but the right and left side I had to take down. I have overlapped on left and rt. side with plastic and was thinking of siliconing or strong duct tape at seams. Is this necessary? Will this be OK? Thank you.
Dick
Hey Dick,
As long as you have them overlapped it will be fine. You can silicone or tape it if you want, but no real reason to do so.
when tiling a shower with a cement pan (built in place) should the walls be tiled first and the floor second, or vice-versa?
Hi Greg,
As long as your shower is properly waterproofed it makes no difference which is installed first. I think it looks better with the floor installed first and the wall tile on top of it, but that’s all it is, just a personal preference.
Roger,
should I place a plastic membrane over 2×4’s then hardibacker and add redguard over entire surface. Will this be the mold sandwich. Am I better off with membrane then hardibacker and redguard on seams only.
Which is better? durorock or hardibacker
Great info. Thanks for the help
Hey Dick,
Yes, that is a mold sandwich. Since you have redgard it would be easier to forego the membrane behind your backerboard and silicone the membrane to the back of the backer around the niche, then redgard the entire face. You can also apply the redgard to the seams only without a problem.
If you ask 100 tile guys which is better, you’re gonna get 50 of each answer.
It really comes down to the application (which is NOT suitable for certain applications like steam showers) and ease of use. The second being subjective. I prefer hardibacker, I think it’s easier to cut and a hell of a lot less messy. I don’t like durock much, especially when I have a choice.
Thank you for your quick response. Again great web site.
Another question: I was ready to place 4 mil. of plastic and I am glad I saw this site(TY). hardibacker to studs 1/8 space between pieces and in corner also or do I butt sheet to sheet(sounds like space from your forum).
I want to make this niche water proof so redguard the heck out of it. Should there be space in niche also with hardi or butt joints?
I am sure I will have more questions. I want to do this like a pro and not have issues later on. Much appreciate the help. I am in New England area. Again excellent
Hey Dick,
You’ll want to leave about a 1/16″ – 1/8″ gap in the corners then use thinset and alkali-resistant tape to fill them in, similar to drywall. Once that cures you can redgard everything to waterproof it.
Roger,
Thank you again. Another 3-4 questions as I move on. There is about 3-4 inches between shower studs and studs behind where insulation and 2×6 studs are for outside wall In that area of 3-4 inches 1. Can I add more insulation or is it fine. I do not have backer for niche. 2. How can I secure backer of wood when I do not have access to nail from back. Also when you say attach membrane to backer once I get it in, 3. Do I use silicone behind wood or in front and then place hardi over plastic? I hope this is not too confusing. Thank you for all your help as I work through this project.
More insulation isn’t really necessary but it never hurts. You’ll need to add the backer to either the front of the 2×6’s and use that as the depth of your niche or cut a piece of backerboard to the proper size and screw two 2×4’s to it, then install it into the wall. It’s a tight fit but if you don’t have access to the back and there isn’t a solid substrate back there you’ll need to basically fabricate your niche then install it or build the niche then install your backerboard. You want to silicone the front of the plastic barrier to the back of the backerboard. The barrier is stapled to the studs, then silicone is installed around the area cut out for the niche, then the backer is installed. If you already have your backer installed just silicone between the plastic and backer once you get your hole cut out for the niche.
Roger,
Thank you for answering. I am still a bit confused. The insulation part I get. For a backer I use 3/4 plywood and silicone plastic to the back of that then place hardibacker board into the niche with screws onto backer and the sides of 2×4’s, then redguard whole area? Is that right?
Also I only redguard where the seams are with the thinset and tape on the hardibacker or do I redguard the whole inside of shower. I know I should not put plastic behind. hardibacker due to mold .Great site and terrific info. Thank you for your patience
Roger
You are getting me through this project step by step and I do appreciate it. I sent off a question last night and have another one and you haven’t even answered my question from last night so I do apologize but want to do this totally right.
The mudd for pan was sloped and has been in a week. I did not put hardiboard in prior to last mudd job after liner. What is best option now and how far can I bring board to mudd floor(1/4 “, 1.8 or all the way to floor) I will be doing tiling myself. The person who did job was great. Thank you again. I am sure more questions will follow-here it is. When cutting out hole for shower valve, how do I waterproof that area? Thank you. Dick
You can take hardi all the way to the mud if you want to. I would leave about a 1/8″ gap at the bottom to compensate for any movement – that would be a better option. Use silicone to waterproof your shower valves. The same way you silicone the barrier to the backer around the niche – do that around the valves as well.
Hey Dick,
Yes, redgard the entire inside area of the niche. If you have plastic behind your backerboard only redgard the seams if you want to (not necessary, but doesn’t hurt). The only time you redgard the entire inside of the shower is if there is no barrier behind your backerboard.
Hi Roger,
when we initially talked there was a mention of a mold sandwich if I put plastic onto studs then hardibacker.
This is what I plan to do step by step:
1. 2 outside walls to shower and 1 inside. I am going to place hardibacker against studs then tape seams and redguard seams when taping is dry.
2.place hardi backer i/8 inch from final mudd job on floor(got that)
3. When making nich-prefab with 3/4 inch plywood for back and 2×4’s
then take plastic size of 3/4 and w/silicone place in in between hardibacker and plywood.Is that right?
4. Make hole on hardi backer just large enough to go over shower valve(one)-I do not understand where I would silicone plastic as you mentioned to make water tight around valve.(I am more of a visual learner but please try again. Plastic or no plastic is a bit confusinfg to me. 2 ways have been mentioned. If you were doing this which would you do to take away no mold sandwich without using kerdi
I believe if these questions are clarified I will be on my way.I hope. You should write a tile book. Great information.Thank you so much. Best site around. When you say backer do you mean hardi or wood backer? Thanks
Dick
Hey Dick,
When I say backer I’m referring to the cement backerboard. I believe there is a misunderstanding about what creates a mold sandwich. If you put plastic over the studs then install hardibacker that’s fine. If you install the hardibacker to the studs and redgard the whole wall – that’s fine. What creates a mold sandwich is installing plastic over the studs, then hardibacker, then redgarding everything. The two barriers – the plastic and the redgard – with the hardi in between them is the mold sandwich. You want one barrier or the other – not both.
If you install the backer directly to the studs you without the plastic you need to redgard the entire shower. If you install plastic first you do not want to redgard the entire shower. All your questions I’ve been answering have been under the assumption that you’ve installed plastic over the studs, then installed hardibacker. The hole for the valves also assumed you already had plastic over the studs, this is what you would silicone to the back of the hardi. The niche also assumed this. The plastic installed over the studs would be siliconed to the back of the hardi, then the inside of the niche would be redgarded. The plastic would already be installed over the studs on the wall – this is what would be siliconed to the hardi.
Roger,
Thank you for your patience and all your advice. It has made this tiling job enjoyable and yet I know it will be done properly. This is a great site and I appreciate your getting back to me promply.
I will probably be asking more questions but I am more than impresses with how you do your work.
Thank you.
Dick
Hi again Roger,
While using a grout saw on thinset between my shower tiles, I put a nickle sized chip in one of my shower tiles. Of course, it was on the bottom bordering the tub, so not an easy one to get out. I’m wondering the best way to get it out without damaging the backerboard or redguard. If I could find the chip, I’d just try the epoxy glue on it, but I can’t since there’s too much crap in my tub. Have any advice?
Thanks
Yup – I have advice – find the chip.
Short of that you can take a hammer and beat the crap out of that tile until it is cracked into a bunch of little pieces and pry each one off. You will likely take the redgard off with them. Run a razor knife or blade around the tile so you don’t compromise the seal on the edge of the adjacent tiles. You can then just reapply the redgard behind where that tile was all the way to the edges and reinstall that tile.
And quit twisting your grout saw.
Here I am again! My tile job and shelves (thank you very much for the directions) don’t look anywhere as great as yours, but it’s going to have to be good enough. We are ready to do the side with the plumbing now, and I’m just wondering how to handle that huge hole for the valve (as far as waterproofing goes). Once again, I can’t find a site that explains how to handle that. If we tile up to the edge as far as possible, the tile covering the open area in the wall won’t be waterproofed. Since tile isn’t waterproof, that would allow moisture to permeate through the tile to the back, right? I’ve read to use plumber’s putty to seal the escutcheon, but that won’t keep water from permeating the tile outside the escutcheon, and potentially leaching through that area. So I just want to make sure all my waterproofing (redguard) wasn’t in vain by letting water seep into that hole. How do we handle that?
And once again, thanks for your patience in constantly answering questions for novices like me!
Hey Renea, long time no see!
As you tile, before you place the tile around that opening, run a bead of silicone around it. Make sure the bead is thick enough to contact and seal between the back of the tile and the redgard. Then when moisture runs down from above that opening it will run around the bead of silicone and continue down into the drain. Let the plumbers play with the plumber’s putty.
Roger, is there a current TCNA and/or ANSI standards pertaining to installation order for showers & bathrooms. In other words is it recommended to do the floor 1st and then the walls? Thanks
Hi Brantley,
Nope, strictly dealer’s choice. One or the other is not going to compromise your shower tile installation provided the substrate is properly prepared. I actually do both, depending on time and layout leads me to chose one over the other. It always looks best (I think) if the wall tile covers the edges of the floor tile – but that’s all it really is, aesthetic.