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.
I just found your website and I’m hoping you can dazzle me with your brilliance for a few questions my contractor couldn’t answer. I’m having a new shower built, and right now, everything is done and ready for tile. I initially was going to use regular porcelain or something like that, but after researching, I really want to use (I know it’s strange) real pennies as the shower floor tile. I’ve seen it done on multiple websites and there are instructions and everything on how to do it. Problem is, my contractor says the pennies are too thin, and the drain is now too high or something or using the pennies would mess up the slope (there were a whole host of complaints about the request to use the pennies). Isn’t there some way that he can (a) lower the drain (it is the adjustable kind) to compensate for the thinness of the pennies or (b) reduce or increase the slope to the level appropriate to accommodate the pennies ( I read a post on your website about using ditra to make tiles with different thickness even)? I don’t want him to tear everything up and start over because I think there should be some way to salvage this. After all, I didn’t have to pick out the specific tile I wanted before he did the shower floor slope or anything, so he should be able to put any kind of tile on there and make it work, right? He said that he could tile the shower regularly and then i could put the pennies on top of the shower tile and re-grout or something crazy like that. that didn’t sound right to me. I’ve looked at your website extensively and it looks to me (for what that is worth) like he did everything properly with the slope, waterproofing etc. But I really want this penny thing to happen if possible. Please help!!!
Hi Kris,
You don’t want the ditra used on a shower floor, and it shouldn’t be used on any floor with tiles (or pennies) smaller than 2″ square (or round). The biggest problem is that the height of the TOP of the drain is more than the pennies. Even at only 1/8″ it still towers over the height of the pennies. Once the top slope is done you can’t really make the drain top flush with, or lower than, the top of the deck. The deck can be built up, but it would need to either have the top deck removed and redone higher or built up 3/4″ higher than it is now (provided there is enough upward movement for the drain). You can not put a thin layer of deck mud over deck mud, it will flake away.
Roger…Roger…Roger…
Your ebooks are wonderful but I made the mistake of showing your site to the wife otherwise know as “She Who Must Be Obeyed”.
So….I’m just sitting around have a Root Beer after taping and finishing off the Durock walls in my traditional shower and she sends me a link for a border that she wants. Listello Tile Mosaic Borders.
Four inch or so with a wavy line in it. Very small pieces. I mean really small.
I think I can do it but I have no idea how I’m going to cut them at the corners to continue the wave thing.
Any thoughts? Wet scroll saw maybe?
Signed
Three Fingers…don’t ask.
Hey Pat,
If by ‘wavy’ you mean in the z-axis – 3d – then they should be exactly the same pattern from tile to tile. In one corner miter two pieces so they fit together pattern-to-pattern. If you’re lucky the opposite corner will end on a full tile (but it won’t). If not then lay one tile over the end piece until the pattern matches and that’s where you’ll miter that corner.
The vapor barrier on the outside of the house, I recently bought a new home that was built in 1941 I think it had car siding on it originally but it has vinyl on it now the thing is I think it was a year with innovative new product choices and instead of lath backer for the plaster they had a ⅜” x24″ drywall backer. Previous owners of some year had the walls core drilled and blow in insulation put in all the exterior walls and the attic area but there is some kind of exterior sheet that’s 24″ wide layer horizontally kind of like a cellotex or foam but this stuff is black it feels like a hard plastic and im not sure if its a vapor barrier or insulation or what the properties of it really are maybe you might know. Its a story and a half with a 9/12 pitch on the main roof A frame and the back of the house has a hip roof that is 12/12 to accomadate the stairwell. I’ve built a shower before out of rubber membrane material and sand and porland cement mix but it didn’t have a window but im reading here that the cement board above the rubber membrane is not really water tight at allots not on an exterior wall but sense the rubber floor pan stops a foot or so does that mean nothing above that is water tight
Hi R,
Yes, if you only have backerboard above the rubber membrane then it is not waterproof. Is the product on the shower side of the studs or the exterior side of the studs? Either way if backer is up there it is still not waterproof if there is not a continuous membrane directly between the studs and backer.
Hey Roger…..I have tried to contact the manufacturer with questions without any luck I want to use the spectra lock but have never grouted before so here goes.
1. Their grout calculator at 18 X 18 X 1/4 with 3/8 joint and the mini shows 31ft sq do you know is this 31′ of grout line? Also I don’t know what size the store has but the color part is like a quart milk container size. I was thinking of using the smallest one since I have never done it before and I don’t have a scale to split it up into smaller sizes.
2. I am using bull nose as base board should I grout the floor before installing the bull nose or install and grout all at once? Same question with the shower floor?
3. If I need multiple grout packages do they have lot numbers to get the same batch or do I need to worry about that with this product.
4. when applying do I screed off level and it shrink when it cures or do I finish it by pushing hard with the rubber float to get the level I want at finish with out shrinkage?
Thanks for all your help Roger I don’t think I could have pulled the trigger on this project without your site to help!
1. It is 31 square feet of tile. The quart-sized container is 1/4 of a full unit – a mini-unit.
2. You can do either. The transition space between the floor and wall needs to be siliconed, not grouted.
3. Yes, or you can just mix all the powder together to ensure consistent coloring. You should do that anyway.
4. Just like regular grout – clean it level (or the finish you want).
roger I was intending to install bullnose as baseboard trim and assumed I could do it right over the drywall that was finished and painted then I started thinking about what assuming usually gets me and thought I’d better ask and if I can is there anything I need to do in prep and what size trowel would I use for that application. thanks again for all your help
Nope, you can go right to the painted drywall with base tile. Won’t hurt anything at all.
Do you recommend thin set for the bull nose base board or should I use an adhesive and calk gun for for this to the drywall? I have seen both done but then you can find anything on the internet…….
Thinset.
Roger I can’t seem to find anything to let me know how long I need to let the spectra lock cure before I turn on the floor heating. I can find about fullysubmerged applications, shower and staining but not floor heat. and I can’t ever seem to get through to technical supportand the impatient half of our home doesn’t want to wait to 7 days I was going to wait.thanks again for all your help!
Hi Gem,
It needs about seven days. Whether everyone wants to wait or not.
It’s not so much the spectralock as it is the thinset cure – if you rush it you may weaken the bond.
Thank you roger for the quick response I have way more than 7 days on the thinset that but only 3 1/2 days on the last batch of spectra lock and I can find anything on the spectra lock specific to floor heating
You should be fine. Three days is enough for the spectralock.
Hi,
I am trying to fix my intersecting plain joints and tub line for a porcelain tile backsplash. The gaps are 1/8″ to 1/4″ at the tile and similar at the tub. at some points these are 1/2″ deep. I used 100% silicone sanded grout, but it peeled away from the sides of the tile in places just enough to get a little yucky. Now the silicone is cleaned out and I need to replace it. Is there a place to go to see how to correctly do the seal so it does not peel back again? like a cross sectional view of how the joint should look. (I had it looking like grout the last time, parallel with the tile.) I planned on using the silicone again, or maybe not sanded.
Hi Kevin,
There is no such thing as sanded silicone grout. I have no idea what you may have used there. If your gaps are that large you should have backer rod in there, which is round foam you stuff in the gaps to fill most of it. Then the silicone goes right over it. Without that large of a bead in there it is not nearly as prone to shrinkage. I don’t know of any cross-section view like you describe. I’m sure one exists, I just don’t know where. You should use 100% silicone.
Hi,
The product I used was called Color-Sill from Color Rite inc. I like the finish texture and look of it. The web site is:
http://colorriteinc.com/color-sil.
My question concerns the best way to form a bead when you silicone a gap between the tile corners and the tub. Here is an image I have drafted at photobucket:
http://i1104.photobucket.com/albums/h334/wraiththe/Shower%20Project/cornerbead1.jpg There is an insert of the failed caulk after cutting… and then a corner during cleaning.
Unfortunately I tried to do it using 30 minute 100% Silicone from GE. I will have to do it over. Feel free to browse around if possible.
They can (and obviously do) call it whatever they want but all it is is sanded silicone. The grout portion just indicates that it is colored to match grout. I’m assuming the caulk portion is just to get people to know what it’s for. Silicone and caulk are two completely different things. What you have is 100% silicone with sand in it. I don’t like the sand portion, but there’s nothing wrong with it. The third and fourth examples – which look identical to me – would be the proper way to do it.
My Bad, I had very little sleep. I should have said Sanded 100% silicone used to caulk the tub and match the grout. Thanks for the input! For the record, the Color Sil looks so much better. The difference between a luxury hotel highly professional look and a Joe Schmo cheap contractor look.
Kevin
It wasn’t you, Kevin. On their site they actually have “100% silicone SANDED grout caulk”. I believe the grout caulk is simply to describe what it’s used for, but I don’t know the reasoning behind calling it that, it’s a group of words that don’t belong together. It’s their bad.
Greetings:
I need to cut tile (1″x6″) arount tub edges between the tub and the wall tiles, but I do not know how to cut the little corners.
Can you please help?
Thank you
Hi Angel,
I can’t really tell what you’re trying to do. I don’t know why you would need to cut in tiles between the tile and tub. Do you mean the bottom row of tiles that go down to the tub? A wet saw or grinder is about the only way to cut inside corners out of tile.
Hi Foor Elf,
I plan to tile over ceramic tile in my shower. The existing tiled walls are very sturdy and have been well constructed so I don’t want to rip them down.
For the new tile, I plan to use 1″ x 1″ glass tile, so I am interested in what specific adhesive you recommend.
thanks
Steve
Hi Steve,
You need to get a thinset approved for such an application. Mapei ultrflex 3 and laticrete 255 are two such thinsets, although there are other. However (!), I WOULD NOT install glass tile over existing tile. No specifications explicitly prohibit it, but they also don’t specifically prohibit installing tiles made out of rice paper. (Just because a particular installation is not prohibited in detail does not mean it’s an acceptable application)
Any advice on adding a flange to the 4th side of a Kohler cast iron shower base? I want it to be a walk in, doorless shower. We want to add a partial pony wall to the 4th side. Thanks!
Nichole
Hi Nichole,
You really can’t add a flange, but you can still waterproof it by attaching the backside of your waterproof membrane (whatever that may be) to the horizontal arm.
I am about the install a kerdi shower system using drywall as my backer substrate. One of the shower walls is an exterior wood framed wall with R13 insulation. Am I correct in interpreting the above article in that I should slit the insulation in various places to allow any water vapor to evaporate through the facing of the R13? I was under the impression the kerdi is 100% waterproof so how would water vapor get behind the kerdi to the drywall and then behind the drywall to the R13?
By the way I love your website.. very informative and full of good reads!
Hi Tim,
Yes, slice it in each stud bay. There is always moisture in building materials. It normally dissipates with no problems. If, however, you have two barriers like that the moisture can get trapped between them which will lead to mold.
Hi Roger, I’ve bought your books and searched your site but I can’t find something I need. We are building a shower and I want a bench seat. I plan on using traditional method with an acrylic shower pan ( already in place). There is space between the wall and pan to frame out the seat. I’m thinking that I need to treat the studs of the bench seat like a wall, put plastic over the framing, down over the flange of the pan, silicone plastic to the flange and use cement board to create the bench, am I on the right track? Are there any other bench seats posts/projects you can direct me to on your site? Thanks!
Karen
Hi Karen,
I don’t yet have anything about benches. That’s very high up on the list right now. You are correct, though, it’s built exactly like the wall. The only difference is the horizontal portion on top which needs to be sloped toward the shower floor, but it gets treated just like a wall with the barrier as well. Around the corners and edges of it you can use silicone to bond the barrier to itself if you need to cut it anywhere.
Hi again Roger!
Thanks for the feedback. Is there a particular degree of slope to the seat? I don’t want to slide off while I’m shaving my legs lol
Thanks!
Karen
Hi Karen,
Sorry for the delay, been out of town at the new Schluter facility all week.
Technically you should have the 1/4 per foot slope there as well. It’s always best, although you can actually get away with about half of that if you want. Just don’t tell the tile police I said that.
Hello Roger…
Great to get straight up answer. I hope i can get one as well. I attempted a barrier free wet room. And I did not do a great job of sloping. The water goes straight to the bottom of the bathroom out the door. Duhhhh. I was hoping for some suggestions? I am in desperate need of some expert advise. The bathroom is basically completely tiled. The waterproofing was extensively research. I just did a poor job on the slope. I was looking at the Kerdi curb but i can only find it in 48 inches. I found the Wedi curb and it is 60 inches.
My question is, is there any way to put some sort of curb on top of my tile and water proof it as best as possible. Or plan b, cut the tile some how where the curb will sit. Then sit the curb on the morter. Then water proof it as best as i can, kerdi paper or some red guard, and some pan liner? Then put tile on top of that. Please need help!!!
Hi Waziri,
You can attach a curb to the top of your tile, but it won’t do what it needs to do. Mainly – waterproof your room. You need to tie the waterproofing on the curb to the waterproofing beneath the existing tile, otherwise you’re just wasting time and materials and the only thing it will do is destroy your non-waterproofed subfloors (outside the room) more slowly. So you’ll need to remove at least enough tile to tie waterproofing from the curb to the waterproofing beneath the tile.
The bigger problem, I think, is that even if you get the curb and waterproofing tied together all you’ll accomplished is holding the water back and containing it in the waterproof areas. That is only half the need, you still need to allow that water a place to dissipate. Normally a drain at the lowest portion of the floor, in this case being your doorway. So you can contain the water, but it’ll just sit there.
To be honest the only true solution is to remove your tile and slope the floor correctly. I know that isn’t what you wanted to hear.
Hello Rodger,
I have been searching your site, but have not been able to come up with my specific question. I am using regard over hardiebacker for my shower. have not decided between porcelain or ceramic yet. Do I need to use an unmodified thin set? I would think so, but I thought that i read somewhere, regard recommends using a polymer modified? Help.
-Brandon
Hi Brandon,
You want to use modified thinset on redgard. The only product that requires unmodified is schluter (kerdi and ditra).
How high should the Kerdi go up the shower wall ?
To the showerhead?
How high is the showerhead usually?
Hi Edward,
It should be a minimum of 2″ above the shower head. They are typically installed at 6′ – 6’6″, but most of my client’s have me raise it. I normally put it at about 7 feet.
OK, First time doing this, read your comments, but the words are a bit confusing for me. Be patient, first time at this.
I want to install a cast iron Kohler tub (alcove – 3 walls). 2 walls are interior exterior walls, 1 is interior. I plan to use 1/2″ USG Durock Cement Panel and use Firerglass tape for the joints. How much of a gap do I leave between the cement board for taping. USG says to use Type I Organic Adhesive or Latex mortified mortar (dont know what that means)…is this to affix the all the tile including putting either one of these adhevises over the fiberglass tape, and is this all done at the time of tileing?). Do I leave a 1/4″ gap between the end of the cement board and the top of the lip on the tub OR the top the tub surface (dont know which one I should measure from). USG says to caulk the 1/4″ gap below the cement board which basically fills in the space back to a stud or open space (is this correct?). If so, caulk with what? And, it would seem to me that I have to tile before I caulk in that space. My tile will be so that the bottom edge of the tile will be 1/8″ above the tub surface? Do I caulk that space also before the grout? I was going to just grout, and then put clear silicone over the grout. I am attaching their link that I was referencing….pages 6 and 7. Sorry if you answer this stuff already but I dont want to take any chances.
Thanks
http://www.usg.com/rc/system-catalogs/durock-cement-board-system-guide-en-SA932.pdf
Hi Armando,
Leave 1/8″ gap between sheets of backer and use thinset and fiberglass tape (backerboard specific – find it in the tile section) to tape them. Regular modified thinset is also called latex modified mortar – same thing. These are products sold in 50lb bags that you mix with water, like versabond or mapei ultraflex. That portion can be done beforehand or while you’re setting tile, up to you. It’s normally easier before you set tile if you haven’t done it before.
Ideally you leave 1/4″ gap between the backer and the top of the tub arm, it should be placed over the front of the flange (lip) of the tub. You will need to shim it out from your studs in order to keep it flat so it doesn’t bow out at the bottom where it goes over the flange.
The issue of caulk and where it goes depends partly on which type of waterproofing you’re using on your walls, you haven’t mentioned any. If you are unsure you can download my free shower waterproofing manual which will explain the different methods and which may be best for your project here: shower waterproofing manual.
I’m wondering how to set the bottom tile on tub flange – should I thinset or silicone the bottom back of tile where it sets on the tub flange?
Hi Dawn,
I already replied to your email. If you would, please only ask your question once (preferably here where it may help someone else), I will get to it, but I have a day job.
I answer 40 – 50 questions a day, it stretches it out if I need to answer them twice. 
The tile doesn’t need anything behind it at all in that area. You can put silicone there if you want, but it’s not necessary. Do not use thinset there, it will crack out due to differential movement.
Siliconing the space between the (I’m assuming) the bottom of the wall and the tub apron depends on what type of waterproofing you’ve used. If it’s traditional the membrane behind the substrate gets siliconed to the front of the flange, if it’s topical that space gets siliconed and your membrane goes over it – unless it’s a topical board, in that case just silicone.
HI Roger,
I am in the process or retiling my bathroom. I am using kerdi over hardieboard for the shower surround (3×6 subway tile) the bathroom floor will be 12×12 marble. I have put down hardieboard on the floor and wanted to know if I should Kerdi the floor as well (I have extra on the roll). Also should the same unmodified thinset be used for both types of tile. One more thing. How many bags of thinset to kerdi and tile on 65sft on the walls and 25sqft floor.
Thanks
Mike
Hey Mike,
No real reason to use kerdi on the floor but you can put it in front of the shower if you want to, just keeps everything completely dry there. Yes, same unmodified for both. You’ll need about 1 1/2 – 2 bags.
Hi,
My contractor is currently a little confused on a good waterproofing method for the shower floor. As we have been currently using Schluter Kerdi for the shower walls, we would like to use it for the shower floors as well. However, he did come to us with an interesting comment, he said that since he uses cement to build the slope of the shower floor, he’s afraid that the cement he uses will crack over time and poke a hole in the Kerdi membrane. After some rather haphazard research, we have concluded that he should use the Schluter Ditra over the cement he plans to use though we aren’t completely sure that will be ok since using it for tiled shower floors since Schluter Ditra doesn’t seem to recommend installation in shower floors as a recommended usage. I’m very confused. As we are on a tight time schedule for the remodeling, we won’t be able to purchase a whole Schluter Kerdi shower system kit.
Any suggestions? Sincerely,
A very confused homeowner
Hi Raina,
If he’s using cement for your shower floor he’s doing it wrong – it needs to be deck mud. The reason deck mud has so much sand in it is to prevent cracking. Schluter may not recommend it (because they want to sell you a $600 piece of foam) but they don’t ‘not’ recommend it. Until they came out with those pans it was the only option for a topically waterproofed floor – it’s why they have the drains. They were created long before the pans, the pans were manufactured specifically to fit the drains they already produced.
Use deck mud on the floor, the kerdi drain and the kerdi membrane. It’s completely acceptable and one of the best waterproofing methods out there for a shower floor.
Roger,
Is it acceptable for a tiler to make the curb with 2×4’s then bring liner to top of curb, cement board then use nails at very top of curb then water proof with hydroban on whole floor over curb. LOOKING FOR YOUR EXPERT OPINION. Tiler doing mud job with liner with slope
Thank you again.
Paul
Hi Paul,
There should not be a liner, a mud bed, then hydroban. It creates the two waterproof surfaces (mold sandwich). A liner can be used on the floor then hydroban over the curb as you describe, but the hydroban should only be installed on the floor 2-3 inches out from the wall or curb, not the entire floor.
Roger,
I think I know what you are saying. Mud job with liner on floor. No hydroban on floor except for 2-3 inches from walls and curb and seams in floor.
Tiler says no need for mud and lath over curb. He waterproofs it bringing liner to top of 2×4 curb, cement board(nails or screws are at very top of curb, then hydroban whole curb. Hope this is not too confusing. I am getting dizzy just talking about the different methods.
Thank you,
Paul
I understand what you’re saying, but it isn’t an approved method. That said – it can be done, and it should work fine in theory. However…
The only thing I would add is probably a bead of silicone at the hardi/liner transition so the water does not wick up the backside (not waterproofed) of the backer on the curb. Wicking water through the backer is the reason I would not build a shower in that manner. In all reality a shower curb should not be built like that. The curb is normally the first area that will receive and show water damage, piecing together different unapproved methods there is not a good idea. The transition of the hardi (or whatever backerboard) to the liner and floor is where problems will arise. Backerboards wick water, even if they’re waterproofed on the surface. If there is not a watertight seal between the topical waterproofing and water exposure you will have water in the backerboard behind your waterproofing.
Roger,
New situation. Vinyl window with a wooden frame that protrudes out beyond vinyl about an inch. The window is in a shower area that is gutted and soon to be tiled. Was thinking of cutting back wood (with a feinmaster tool) flush with vinyl window .
What will be best way to waterproof this window when tiling?
Would love to send a picture so you can comment. Where would I send or do I need to?
Thanks Roger.
Paul
Hey Paul,
The best option would be a liquid waterproofing membrane like redgard or hydroban, kerdi works as well. Tile can be installed directly to either.
You can upload pictures here: photo upload.
Roger,
I just purchased your Kerdi Waterproofing 3pk Bundle of eBooks and I am still in the planning stages for my shower. I am trying to mentally go through all the steps and the one thing I can’t figure out is how do I apply schluter to ,what I am going to call a inside/outside corner. To explain further, my design has two benches in it. One running along the entire length of the shower and one running along the width. How do I Schluter the corner where the 2 benches meet? (I don’t think schluter can be used as a verb but I hope it works in this case)
Thanks
Hey JC,
Schluter and kerdi both can be used as a verb.
The outside corner pieces that are included with your drain will fit onto that corner. They just go on backwards with the short fold down the vertical corner.
Roger,
I have installed Durock in a tub/shower surround. In the back corner, I have ended up with a gap between boards. Basically a V shaped gap that runs a foot, and ends up about 1/2″ wide. Bad measuring/cutting on my part. I plan on taping the corners with fibatape + thinset. Should I fill the gap with caulk or thinset prior to taping?
thanks,
Chris
Hey Chris,
Thinset would likely be your best bet there before you tape and mud it.
Hi, I have put my membrane in (pan), mud pack, laid the floor but i used the Masonite shower board for the walls (to save), glued to green board, tiled the bottom one foot up but now have the Maronite wicking moisture. I have checked the crawl, no sign of moisture. Is there anything i can use at the cold joint where the wall tile meets the floor from outside (inside of shower) the joint? Thanks
Hi Dave,
Silicone would be about the only acceptable product in that space. You should also replace it about once a year.
Hi Roger! I am currently in the process of taping and applying thin set mortar to the cracks between cement backer we have laid to the floor of our bathroom to get it ready to tile. I am just unsure of what to do with the gap between the tub and the backer. Should I fill it? Leave the gap? Tile over it? Thanks in advance!
Aimee
Hi Aimee,
You need to leave that gap (or fill it with silicone) and tile over it. Leave a 1/8″ gap between the tile and tub and silicone it.
Great! Thank you. One more question as far as where the toilet will go: it isn’t installed yet and there is a small bit of sub-floor showing around the hole for the toilet. After tiling a square hole around that, will it be fine if we instal the toilet right on top of the tile and just seal up where it meets the tile? Or should we do any more to the hole where the sub floor is exposed?
It will be just fine to install the toilet right over it.
Roger
We are using red guard waterproofing on plywood . I am thinking of using wire mesh nailed to this, then mortar to level the uneven slate that varies from 1 to 2 inches thick This is a exterior porch we are doing. thanks Dave
Hi Dave,
Was there a question you needed answered, or are you just letting me know what you’re up to this week?
If the question is along the lines of ‘is this an acceptable method’ then the answer is not really. You can not use mortar to make up for a 1″ height difference. You can put deck mud over the redgard, then a layer of thinset, then beat the slate flat while it’s all still malleable. It’s called the ‘wet-set’ method. It’s extremely old-school and still about the only acceptable method of laying stone with that much of a variance.
Roger, back to working on floor after demo. Two baths
One bath has plywood and was tiled directly to plywood with no problems.(cracks etc.) I do not like to tile to plywood but can I use 1/4 inch hardi or 1/8 ditra, mastic and tile(mastic underneath hardi). The flange right now is 1 inch above solid plywood. Can I dofloor before they decide on one piece shower or tiled shower? will follow up with questions on larger bath later.
Thank you for all your help over the years.
Hey Paul,
NO! Unless by ‘mastic’ you mean ‘thinset’ – two different things.
If you mean thinset then yes, you can use either the 1/4″ hardi or ditra. And yes, you can do the floor while you’re waiting for them to make ANOTHER decision.
Thank you Roger. I did meam thinset. Now for bathroom number 2.
It is down to studs. floor has those older sub planks. what to do to get to code and add tile? boards are in descent shape except by old drain(couple of holes), not as solid. Also have a chance to get a second hand Felker TM-75 for 200.00 on craigs list. What do you think? Thank you again,
Paul
Repair the area where the drain was and install an additional 1/2″ or 5/8″ layer of ply, then membrane or backer and tile.
I would grab that 75 in a heartbeat. I have two of them, very handy little saws.
Roger,
Thank you for all your responses. I am a DYI who loves to tile and always borrowed saw but now have been looking on craigs and as I stated looking at Felker(thanks for response) but also have a chance to get fairly new MK-770 for 250 dollars. MK seems newer. Your advice between the two because I am about to make a move with your guidance. Thank you again. doing backsplashes and fireplaces for daughters.
Paul
Thanks,
Paul
Between the two I would go with the felker. Can’t stand the red screamers.
Roger,
Thank you for responses. I am now doing a back splash and there seems to be plywood that was behind formica. Took off the formica and should I tile over plywood which seems stained or put up 1/4 inch durorock.(plywood is much easier for me).
If putting up hardi or cement board, how will I hide how it comes out on sides? This is new granite counter top. Do I need boarder tile(thin strip)? How to make professional and uniform.
Thank you,
Paul
Do not tile directly over the plywood. Ideally you should remove the plywood and replace it with backer. If you put the backer over the ply you will need end caps (bullnose that cuts back to cover 1/2″ edges, made for mud wall edges) or a pencil trim, thin strips of tile, etc. The professional look would be to remove the ply.
Thanks Roger. Problem is there is horsehair plaster behind and I am afraid I will be opening a bag od worms. Will the pencil trim look OKay?
Yup, pencil trim looks fine down the edges.
Hi Roger,
Getting thinset out of small staggered glass and sone tile for backsplash. What is best way to do it?
Also some of the tiles do not have spacing on bottom toward counter. When grouting will this be okay. The spacing with these tiles varies is this normal?
Thanks, Paul
Hi Paul,
A grout saw you can buy at a big box store will take the thinset out of it. Those smaller spaces will be fine, unless they are between the tile and countertop. If that is the space you mean it needs to be siliconed rather than grouted.