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.
Roger,
Love your site! Thanks so much for all the help for those of us who should have multiple copies of “Tiling for Dummies”. To the questions – I’m (via a well checked out licensed contractor) putting in a large shower (4′ x 7’2″) w/ 2 showerheads in a garage we converted to a master bed/bath. In trying to choose tile for the walls – is it acceptable to use ceramic tile (non-vitreous)? It’s 3×6 beveled edge glossy glazed ceramic subway tile. I was planning to stack it in columns and add in glass mosaics every foot using 1/16″ grout lines. Is it a bad idea to use this tile? Another option is to use all glass tile.
Second question – If I use glazed tile or glass tile on the walls, vitreous glass 1x1x4mm mosaic glass (rough texture – floor suitable) for floors and spectra lock, is there any reason to seal anything?
I’ve been advised of TEC’s Power Grout as the holy grail of grout. What do you think? I’ve also been looking at a product by Bisazza called Neutro Fill Gel that is supposed to dry clear. Heard of it or used it? Is it worth hunting down (hard to find in the USA)?
Thanks so much!
Angelia
Hi Angelia,
It’s acceptable to use nearly any type of tile in a normal shower – your waterproofing is on or behind your substrate – your tile has nothing to do with it.
If you use ceramic yes, it will benefit from a sealer, but not in any type of waterproofing aspect, purely from a cleaning aspect. If you use all glass you likely should NOT use spectralock. The different products have extremely different expansion and contraction properties. Unless it is an actual cast glass tile (read: ridiculously expensive) then the glass may end up cracking. That is not an issue when used as only an accent tile, but an entire shower is different.
Power grout is good, but it hasn’t been out long enough for me to give you an honest long-term durability opinion about it. It’s a very good grout, although it’s a bit difficult to work with if you’re not used to it. No reason at all not to use it. Never heard nor seen the neutro fill gel.
I am in the process of rebuilding my shower and installed a pre-molded tilable shower pan liner with a curb and 4″ sides over which the backer board is installed. Unfortunately, not thinking, I drilled four screws through the backer board approximately 1″ from the bottom of the pan base into the sides of the liner. I am questioning whether I need to replace the expensive liner or if 1″ of height above the sloped base floor will provide enough waterproofing integrity. I plan to tape the backer board (Permabase) and use Redgaurd. Any insight would be much appreciated.
Hi Jack,
Oops.
You can replace it, or you can paint redgard over the penetrations. No, 1″ is NOT enough height, it should be a minimum of three inches above the finished height of the curb. However, if you paint redgard over it that will waterproof the penetrations at the surface, so you’re covered.
Roger,
I need some advice for correcting a layout oversight. When I measured the distance from the top of my tub to my ceiling, I thought I was the luckiest DIY’er because my 12″x 24″ bright white rectified porcelain tiles would fit full tiles, without cuts, leaving a 1/8″ gap on top and bottom for caulk.
Of course I used a level and straight edge and began tiling on the second row to allow adjustments for any out of level areas where the tile meets the tub. That part worked out fine.
What I didn’t account for was that the ceiling was not level and I had measured the “happy spot” where everything lined up. The reality is that the gap from the top of my highest (full) tile to the ceiling ranges from 1/8″ to a strong 3/8″ish.
I’m not sure how to aesthetically compensate for my blunder. Do I fill the gap with a paint-able caulk and paint it to match the ceiling (also white)?
My other thought was to use a single, horizontal, one tile, row of the same glass mosaic I’m using as a vertical racing stripe below my exterior window, and within my niche. I would have to apply it on top of the installed tile, however, the tile is high gloss (no texture), so I wouldn’t know how to bond it. Also, I’m not sure if I really like this idea.
I’m sure that you haven’t made this kind of error before, but if you had, how would you remedy it short of ripping the entire project down and starting over which is not an option?
New rule: Measure twice, cut once. But, always measure BEFORE beer!
Hey Tom,
I only did it once. I normally only do it once.
I ended up taking it all down and redoing it – not really an option. The caulk and paint idea is an option. I normally recommend people get a pencil rail or accent piece to install over the face of the tile at the top of the shower. You can bond it with epoxy. The glass idea will work too, but it may draw too much attention whereas the pencil rail normally won’t.
You can also install plastic crown molding up there. I’m not a fan of the look but it works.
I just moved into new construction and found that there is a gap between the top top of the tile in my shower and the wall. It looks like the wall is not square and when they laid the tile, they tried to fill the gap between the thinset and the tile with grout. That, of course, is cracking and falling out. How do I fix this? Its only half a tile long, and about a finger wide. What can I fill it with? I dont want water to collect between the thinset and tile. Thanks!
Hi Joe,
You can use backer rod and silicone.
Hey,
Just wanted to say thank you for your site. You do a great job and provide a great service.
Cheers!
How do you account for thinnest thickness when setting the floor drain height? The tile is 2×2 porcelain. Using a v notch trowel per the title council specs.
Is the drain height adjustable after the mud bed is dry? Should I wait for the mud be to partially cure and then remove the adjustable part of the drain the assure that I can adjust it after the mud bed is set?
Hi Ron,
Yes, it is adjustable. After you get the mud deck packed just work the barrel (the threaded part) back and forth until you can unscrew it freely. What this does is force the mud out of the way of the little nubs on the underside of the barrel and allows you to adjust it as you set your tile.
Roger,
Great pdf on waterproofing, substrates, maintaining a gap between the substrate and tub, etc.
I installed a new cast iron tub and my chiropractor says it’s ok to begin papering the wall and hanging backer board. What do I do with the transition between the paper (15 lb. felt) and the cast lip of the tub. One youtube post describes using an adhesive flashing (Jiffy Seal at Home Depot) to create a seal between the felt and the tub. What about 20 mil PVC tape?
My second question is once the tile is installed, is it appropriate to use caulk between the tub and tile? After all the discussion of allowing the water to drain into the tub, will the frequent practice of using caulk in this gap cause moisture (and mold) to accumulate behind the wall?
Hi Steve,
If it has a vertical flange siliconing the back of the felt to the flange is the way I do it. That said, either of the options you’ve mentioned work as well.
Yes, silicone between the tub and tile, but leave weep holes.
Hi Roger,
For a neo-angle shower what would be the best way to tile the shower curb for a handyman with not much tile experience? The tile I bought for him is a 12×24 rectified porcelain for both floor and walls. It does not come in a bullnose. I still have not bought the shower floor tile. I’m afraid our handyman may not be familiar with the schulter profiles. Can we use a mosaic, river rock or something other than a bullnose for the angled edges that is more foolproof?
Thanks!
Hi Stephanie,
Not too sure what you’re looking for. I understand the question, what I don’t understand is a ‘handyman’ who would not be able to use a schluter profile. It is extremely straight-forward, you don’t need to be familiar with them at all. He could also simply have the factory 90 degree angled edge along the curb. Putting any other type of tile or mosaic on it would be just as easy as cutting down the 12 x 24’s. Nothing is foolproof, if he can’t figure out what to do on the curb perhaps you don’t have the right person building your shower?
Hi Roger,
I’m currently living in Cape Town, South Africa, so some of the construction techniques might be different here, but I’ll ask anyways! A contractor is doing my walk-in shower with 60cmx60cm tile. The substrate is a concrete wall which he has thoroughly waterproofed which what smells like roofing tar. Unfortunately, the wall not completely flat. His solution is to lay blobs of adhesive on the corners of the tiles to make it easier to make them level. However, this is creating an 2-4mm air gap between the tile and the waterproof layer. I’m concerned that this might allow mould to grow behind the tile. Should I be concerned?
Thanks,
Andrew
Hi Andrew
That is known as the five-spot (or however many they’re putting on there) method and should not be used for walls in a wet area, or a floor, or anywhere else for that matter, for the reason you stated. Open space behind your tile is not a good idea.
Hi Roger
I am gutting a shower to make it barrier free (i.e. wheelchair accessible).
I have to decide between installing an acrylic shower pan or having the contractor do a mud-fill and then tile. The tile is much nicer, but will the tiles come lose or crack because of the wheelchair (the whole weight is on four points only!). I do appreciate your suggestions.
Thanks
Jordi
Hi Jordi,
When properly prepared and installed you can drive a forklift over tile on a mudbed.
Seriously.
Help!! My tile guy is installing tile on walls that he floated a few days ago and the walls are cracked. I mean they are beyond hairline and in many, many places. He has all the usual stuff underneath it, aqua bar, lath, etc. and his tile work is very good. But I can’t imagine that this would be acceptable – the substrate is already compromised, in my opinion, and we are adding tile to it? Just doesn’t make sense. Additionally, he does not perform a water test to the pan, and, he does not put any pebbles around weep holes prior to pan float. He is an honorable guy, but…what do you think??
thanks for you prompt reply!
Hi Scott,
I honestly don’t know what to tell you without actually seeing the mud. It will shrink some, but it should be rubbed down before it’s completely cured so it all meshes. There shouldn’t be any cracks visible, although there may be hairline cracks in it. It is a whole different ball of wax to say that the substrate is compromised, though. Although you may see cracks it does not mean that the wall is unstable. If they are from shrinking then they’ve done that all they’re going to, so it may very well be stable.
Some guys test pans, some don’t. All should.
My best advice is to bring your concerns up to him and have an honest talk about your concerns. If he is a professional he will be able to explain what’s going on and put your mind at ease. If he gets defensive about it simply can his ass. Only unprofessional contractors who don’t have a complete handle on what they’re doing will get defensive about a concern.
Hi roger ,
Doing my daughter’s bathroom after other showers and baths with your help. tile man is putting in cooper for 3×5 shower and for curb with 2×4’s . love the cooper for pan but proper waterproofing for curb and for the walls I was going to do kerdi board and have tiler do all tiling and grouting.
Questions
1. When installing kerdi board what do I do with kerdi board and shower floor/ how do i tie in? Silicone?
2. Want this well waterproofed. Using kerdi and cooper showerpan then usinf both Kerdiboard and sheets at edges of board.
3.Can I use kerdi sheet with curb somehow.
Thanks for all the info. I know this dialogue of questions will continue.
Paul
Hey Paul,
1. Kerdi-fix. It’s a urethane-based sealant made specifically for kerdi and kerdi-board.
2. ? no question there I can discern, it’s a statement.
3. Yes. You can build it with 2×4’s and cover it with cement backerboard, then kerdi. Or use kerdi-board – it’s easier.
Roger,
Thanks for the reply. So I can use copper pan and 2×4’s then instead of cement board use kerdi board over 2×4 then thinset and tile? I know you have mentioned you like kerdi board now instead of other kerdi product to cover areas. Seems much easier.
Also bring kerdi board to shower pan then kerdi flex like silicone on bottom- thinset then tile? Do I bring board right to floor or leave an 1/8 of an inch then kerdi flex?
You have converted me to a tile fanatic.
Thanks a million.
Paul
Yes, you can use the kerdi-board. Take it to within 1/8″ of the pan, then kerdi-fix.
I do have to say I have no idea at all why you’re using a copper pan, I haven’t seen one in thirty years. Could be a geographical thing but they’re extremely outdated as they tend to break down over a couple decades of use, due mostly to the alkali in the cement-based products used in tile installation.
Also, if you have any more questions can you PLEASE read the little paragraph between the phrase “Leave a Snarky Remark” and the box in which you post your question? Thanks.
Hi again Roger. I will not use the pan then.(it is used more in northeast) Tile man said it is cheaper but he will do liner if I want.
Where the Noble liner goes over the curb can I do as suggested and place Kerdiboard on top with kerdi strips at seams?
Bring the board to within 1/8 inch of mud then kerdi flex?
I like this product and will probably be waterproofing myself and then have tiler come in. He will be doing the 3×5 floor.
He is much faster than me and has been doing it for years.
I would love to go to Kerdi workshop but not in this area. any suggestions?
Thank you for all your help with all projects I have done.
Nope, if you do a liner you need lath and mud over it on the curb. No way to attach anything over it without puncturing the liner. If someone is doing the liner for you the curb should be part of that shower floor build.
Roger,
If I do the liner and use the kerdi board do I bring the Kerdi board within an 1/8 then kerdi flex to liner then mud over kerdi board on bottom like I would with board? Same with mud curb?
The board seems so much easier than the sheets. I assume the kerdi board goes right over studs?
Do you use the liners and mud method more often than not?
Thank you for all your help.
Paul
No, the kerdi board simply overlaps the liner, which runs up the wall. Gravity prevents water from running UP the wall, no need to use kerdi-fix (it’s kerdi-FIX, not flex. You’re driving my OCD batshit…
) anywhere at the floor. No kerdi-board on the curb, just mud. Again, there is no way to attach the kerdi-board over the curb which will not penetrate your floor liner, rendering it essentially useless. Yes, kerdi-board goes right to the studs. I rarely build showers with a liner and kerdi-board, although it can be done. If I use topical waterproofing in the shower I use it on both the walls and the floor.
Roger,
sorry about your OCD but I am with you. (kerdi fix)
As far as the curb, I understand what you meant. I was talking about the wall coming down to curb where shower door will be. Do I bring the Kerdi board to within an 1/8 of curb similar to wall to shower floor and thinset then tile?
In corners do I use kerdi cut out overlaps? and what about where you use special screws to studs(kerdi fix or thinset) to waterproof them.
Does this have to be unmodified if thinset?
Thank you again for quick response.
No worries, everything bothers me some days.
Yes at the curb, within 1/8″ just like wall to shower floor. Yes, you should use kerdi-band or pieces of kerdi, or kerdi-fix to waterproof and mesh tape and thinset to lock it together. The heads of the screws need to be covered with kerdi-band or kerdi as well, although I’ve used both kerdi-fix and hydroban for those. They do need to be waterproofed.
Schluter wants unmodified thinset on kerdi-board as well.
Thank you for all your help. I am sure there will be more questions down the road. There do not seem to be as many tile setters sold on kerdi as where you are.
Roger,
Quick question about shower curb height. I am getting ready to install my Schluter shower base and curb. The 6″ curb that comes with the shower kit looks way too tall. I would like to make the curb as short as possible (even if some may think it “belongs in a slaughterhouse”) and wondered if you had any height suggestions. Of course the shower base is 1 3/4″ high so on the inside I have a curb height of 4 1/4″, but it still seems too tall. Assuming the floor elf gives me his blessing to shorten the curb, can I just cut down the foam curb before I install it? Thanks ~Nick
Hey Nick,
You can cut the curb down to whatever size you want. I normally have a 2″ inside height on the curb.
Hi Roger,
I’ve changed my email address to: rjrenn@att.net
Hey Roger, with the topical method do I need to completely seal around the shower head pipe and controls where they come through the wall or am I just going to put a half circle bead of silicone on the tile under the cover rings so water is channeled around where they come through the wall? I have seen both suggested and if water does get behind the tile and I don’t have the holes completely sealed what would keep water out?
Just a bead of silicone will work in a normal shower. The amount of water that MAY get behind the tile exactly in the spots between the silicone ring will likely evaporate before even reaching the other side of the substrate. You can completely seal them if you want to, though.
Roger,
I bought and read your Basic Design and Layout for Showers and Small Floors manual, but still have a question regarding layout and uniformity. I am using a 32″x60″ Kerdi shower kit including the curb. I am using 12″x12″ tiles with 1/8″ grout lines and an accent “racing stripe” of mosaic tiles. My question is, do the horizontal grout lines for the first row of 12×12 tiles typically match the top of the shower curb? It seems strange to have a 2″ x 12″ first row of tiles for the shower walls, but I am also very annoyed when I see grout lines that don’t line up.
Hey Nick,
That grout line hardly ever matches up. And it’s also never noticed. Having a 2″ strip at the bottom will immediately draw your eye to it and it will stand out – and look funny. If you use a full tile (or close to it) no one will ever notice it. You’ll have differently sized tiles on the shower floor and the curb is a completely different plane, don’t worry about lining that up.
Dear Elf,
1) Unbelievably I screwed up. Forgot to seal with silicone between the bottom of the denshield and the acrylic shower base. I fully realize you recommend not applying silicone between the bottom of the tile and the base to allow mositure behind to escape, except…
2) Every tile contractor I’ve talked with on the job all silicone between tile and tub and aren’t really interested in hearing the idea that tile is pervious to the point of allowing enough moisture behind that it needs to escape. On the other hand, one guy said that by not siliconing, water can wick up from the base on the back of the tile and eventually weaken the substrate.
3} Given that I screwed up and forgot to siilcone, think it would be worth it in this case to do the otherwise unthinkable? Thanks, and fantastic work
Hi MeL,
Actually I’ve never recommended NOT siliconing between the tile and base (???) unless it was a particular circumstance with someone’s project. The only thing that is different than how most do it is the requirement for weep holes in that bead of silicone. Water WILL NOT get into the weep holes and wick into the substrate – negative hydrostatic pressure prevents it.
Just as an aside, the two things I tell people who do not believe that enough moisture will get behind the tile is:
1) I have A HUNDRED photos of installations I’ve torn out that prove you incorrect. (you can see some of them on my FLAWED page)
2) Science is a wonderful thing – it remains factual whether you believe in it or not.
The fact that many ‘contractors’ are not interested in hearing that has kept me in business for YEARS!
Thanks much for the reply.
Roger,
We have a wood subfloor with 3/4″ plywood over the subfloor making a shower subfloor. Then we slope at the proper 1/4″ per foot using 3/4″ plywood over shower subfloor. Am using a 3-piece drain (divot) with a 2″ tall top flange above the 3 bolts and weep holes.
I talked with some RedGuard people who suggested we can use one layer of RedGuard on the sloped 3/4″ plywood up to the weep holes. Then we add the deck mud to within 3/4″ of the tall top flange, leaving room for thinset and tiles. The RedGuard people said they drill 3 new weep holes where the deck mud meets the tall flange. Then they add thinset (per your manual) and the coat with RedGuard. They say both RedGuard layers then can drain into the original and the top week holes.
Do you see any problems with their design?
thanks,
Bruce
Hey Bruce,
If the redgard people of whom you speak work for the tech department at redgard, and they will send you those specs in writing I see absolutely no problem with it. I would also be interested in a copy of that particular method.
I would not trust my shower waterproofing (even the pre-slope) to a layer of redgard over bare plywood. Plywood expands and contracts – a lot, and having a waterproof layer directly on it is not something I would do. Why would you not create your preslope from deck mud? Why are you attempting to create a method which is actually more work than using the divot method with a single slope? I’m confused. The depth of your slope will need to be the same with either method, so you’re not saving any work there, and using twice as much redgard.
Roger,
Thank you for your prompt reply!
“Why would you not create your preslope from deck mud?”
The NorCal general contractors I interviewed create the preslope from 3/4″ plywood at the level equal to the 3 divot holes. Thus, I added RedGuard at the preslope level.
Then the GCs add 1.25 to 1.5″ of deck mud to leaving enough room for thinset and tile equal to the divot top. The idea is to let water drain through the deck mud to the RedGuard and into the 3 weep holes.
Talking with RedGuard technical support, one person says he adds 3 weep holes and a RedGuard layer at the deck mud level. Complete this layering with thinset and tiles over the RedGuard.
I also think the bottom RedGuard layer on 3/4″ pre-sloped plywood is insufficient protection. Hence the top RedGuard layer is required.
But do the two RedGuard layers, each with their own weep holes trap too much moisture? I could remove the lower RedGuard layer.
thanks
It very well could. You are allowing water to get underneath the top layer of redgard trapping it between two waterproof layers. I STILL don’ understand how this is supposed to be a better solution than a regular divot. The plywood with a sloped deck and a divot is one continuous layer of waterproofing. What you are describing assumes that water will drain from the top layer through the three extra holes into the weep holes. There is no guarantee that the water will end up there at all. Once it gets beneath the top layer it very well could (and probably would) wick into the deck mud – underneath the waterproofing. To compensate for that a full additional layer of redgard is used beneath the entire shower floor???
You said: “Talking with RedGuard technical support, one person says he adds 3 weep holes and a RedGuard layer at the deck mud level. Complete this layering with thinset and tiles over the RedGuard” While it isn’t exactly a good idea to drill holes into a drain that’s not really an issue. His description sounds EXACTLY like the divot method, he just drills more weep holes into the top of the drain.
Just remove the bottom layer and use a regular divot method. When tied into the weep holes water will only go down the drain, that’s it. With a topical membrane you DO NOT need a pre-slope. If GC’s are building it like that they absolutely do not understand what a topical membrane is or how they work. The whole point is to have your waterproofing directly behind your tile so nothing else gets wet. Adding additional layers does not compensate for anything or create a fail-safe.
Understand and thanks.
“Just remove the bottom layer and use a regular divot method. When tied into the weep holes water will only go down the drain, that’s it. With a topical membrane you DO NOT need a pre-slope. ”
With the regular divot method, any water getting under the membrane will seep into the deck mud mix. Evidently the bottom membrane is to keep moisture from seeping into the subfloor. Is it better to use only 15 or 30# felt under the deck mud, then use the standard divot method with a clearance around the divot weep holes?
Thanks
Roger,
As a note, the GC’s in this region use the first described method instead of the original “hot mop” method of prior decades.
thanks
I don’t understand what you’re asking me. With the regular divot method ALL of the waterproofing is at and above the weep holes. There is no way at all that water will get under the membrane and, in turn, no way it would seep into the deck mud. If you need a membrane to keep moisture from seeping into the subfloor then the shower and the divot are not built correctly.
The felt size makes absolutely no difference, it is only there to allow the mud to cure without the plywood seeping moisture out of the mix prematurely, weakening the mud. After the mud cures it has nothing to do with the shower.
The bottom of the divot is at the weep holes in the drain. The membrane is then painted up from the weep holes and onto the top of the deck. This creates a continuous membrane from any spot in the shower to the weep holes. I don’t understand why this is an issue or a question? Is there something that I’m missing here?
Am asking if RedGuard is as good or better than using felt under the wire mesh, upon whch we will add the deck mud? Instezad of felt, a RedGuard bottom layer would also
“allow the mud to cure without the plywood seeping moisture out of the mix prematurely, weakening the mud.”
The rest of the divot technique remains as you specifed.
thanks
It will work exactly the same. It will also cost 40 times as much.
OK, we are following this more expensive technique with RedGuard below and above the deck mud. The deck mud will leave the standard clearance around the divot weep holes.
Surely appreciate your prompt feedback and suggestions when using the water-proof barriors (such as RedGuard).
We purchased Roger’s text; found it helpful to narrow our shower designs and his email replies indespensible. Many thanks.
Roger,
Deck mud was easily applied using a ratio close to 5 parts sand to 1 part Portland cement. This deck has a divot sloping to just in front of the weep holes.
Before applying Redguard on the deck mud, I want to smooth the deck surface so Redguard flows over a very smooth surface. Do you use cement leveler or thinset over a deck before applying the Redguard membrane?
thanks,
Bruce
Nothing. I apply it directly to the mud bed. You can use thinset if you want to, though.
Sorry I can’t find my old thread. I mixed my grout with the admix 2 by Tile Dr, How come when It gets wet it still changes color. Is it not sealed well enough ? Should I seal it again ? Thanks for all your help. Betty
Hi Betty,
If you sealed over the grout after you mixed it with the admix that may be part of the problem. A common problem with grout admixes is the grout will change color when wet (as it would if mixed with straight water) but the discoloration at times is due to what looks like latex leaching. If the discoloration is lighter or almost white it is due to the admix. If that’s the case the only solution (of which I am aware) is to regrout. I would call the tech line for the admix and see what they say.
I did not seal it after installing it because I thought it was sealed because of the admix . It doesn’t get white, it is a almond grout and it gets dark brown. Most of it lightens back up to the normal color but on the seat it doesn’t seem to dry. My granddaughter took a shower friday morning and was away all weekend and tonight it is still dark. There is a glass door so there is not much air movement. any ideas ? Thanks again
Well, ventilation is important in any shower, so if you can remedy that you should. If it is on top of the bench then it is likely that the water is not draining off the top of it quickly enough. Did you slope the top of the seat correctly (beneath the tile – the substrate)? Water should run down the wall, over the top of the bench then down into the floor and drain. If water remains on top of the bench for any significant amount of time the grout will remain darker there. As long as you waterproofed everything correctly it won’t hurt anything, but I know it looks differently and it probably bugs you – it would me.
yes I did slope it and I have my granddaughter wiping it off after her shower, today I told her to leave the glass door open. Yes you are right the color difference bothers me. If it is nothing to worry about then I will try and stop obsessing about it. (easier said than done) . Would her shampoo or conditioner effect the color ? Thanks, Betty
It shouldn’t with the admix. The other option is to remove that grout and regrout it without the admix. That would allow the grout there to dry out. The admix will cause water to be retained beneath the grout as well as keeping it sealed on top.
I think I will see if it dries with the glass door left open before I remove the grout on the bench top. Thanks
Roger,
I’m thinking about getting frameless glass walls and door for the shower surround (two walls curb/bench to celing). I have the Schluter shower system where you get the curb (no bench – Im gonna build mine out of wood) as part of the kit. Now seeing how the curb is made of expanded polystyrene and not wood, how would I have to prepare the curb for the framless glass hardware? Is it better to dich the polystyrene and make one out of wood, or will the curb be rigid enough. I’m gonna tile the shower and curb with 3/8″ polished porcelain and the subfloor is plywood. I have your books, but you only show wood curbs and not sure why.
Thanks,
Mike
Hey Mike,
The styrofoam pans and curbs are products I don’t use. They are rigid enough for the glass hardware or nearly anything you want to put on them, I just don’t build showers in the sizes they make available. If it were mine I would use wood for the curb, but the kerdi pans work just fine. I’d use wood because I’m a stubborn bastard.
Hey jolly young elf:
Did Mike say he is using “polished” porcelain tiles? On a floor? A shower floor? Shouldn’t he be using something less slippery?
Just sayin’….
Joel, I’m using 1×1 inch polished porcelain along with 6×24 inch porcelain wood like tile. With the grout and wood like porcelain tiles, being slippery is not an issue, I would think. The wood like porcelain tiles have a textured wood grain feel adding traction, so I think I’m ok. I would say 80% of the shower pan would have wood like porcelain tiles and the rest being polished porcelain accent. Now the rest of the bathroom including the ceiling (except the bathroom floor) will be 20×20 inch polished porcelain tiles.
Hey Joel,
What Mike said.
Also, just because a particular tile is described as ‘polished porcelain’ does not necessarily mean it’s slippery. The COF number of the tile is what you need to be concerned with, not how it looks. I’ve seen tile that looks like polished porcelain and feels like sandpaper. Size and frequency of grout lines also adds traction to a shower floor.
Marble baths in Rome are tiled completely in marble – it’s slippery too.
How can I unsubscribe? I am done with my building project and want to unclog my email. I accidentally left the below box checked
Laura
Hi Loo,
With every email you get with updated comments there is a link at the bottom to unsubscribe. Just click on that and take yourself off any list you’re on with my site. There may be one on this email that says ‘manage subscriptions’ or something similar, but I don’t know – I don’t get your email.
I do know if you get another update for the thread you’ve subscribed to it will be at the bottom of that. Or if you have any of the ones you’ve already received.
Hello Roger,
LOVE THIS SITE!!!!!!!!
I am now planning my tile layout for our bathroom remodel with a three wall bathtub/shower. I am using a 1/16 spacer for 12×12 tile for the shower walls. I am wondering what my spacing should be in the corners….1/16 or larger? I thought I read something here previously but couldn’t find it.
where the 3×12 border tile meets the border tile going up the shower wall, I am figuring that I just make a 45 dergree cut since the 3×12 tile has a beveled edge?
I am also using the same tile and spacing on the floor….my first bathroom tile DIY, scared to get too fancy, with some 3X12 matching border tile for the wall and floor change of plane, would that be the same spacing at the corner as well?
One more question,
Thanks for your help,
Robert
Hey Robert,
1/16″ in the corners. Yes, same spacing. Yes, 45’s are typical and look best.
Sorry, I’m not wordy today, not enough beer yet…
I greatly apprciate it!!!! Off to full on planning now!!!
Hey Rog, Wondering which methods you would advise be used or which method you see as more appropriate in shower construction: 1) applying a vapour barrier behind cement backerboard when constructing the walls of the shower and then tiling directly to the backerboard, or forego the vapour barrier and paint on a waterproof membrane on the backerboard and then tile on to this waterproof membrane? will the trowel notches not scratch this membrane? Secondly, do you prefer embedding your backer board in the mud shower pan, or resting it atop the shower pan? 3) in the construction of the shower pan I was thinking this time to forego using a shower pan liner at all and just apply redguard to the surface of the mud deck pan, many coats, so that it is entirely waterproof, however i ve noticed you havent really advised this method so am apprehensive to actually do it this way, Thanks Rog! The floor elf knows best.
Hey Jake,
I prefer the topical methods over the traditional, so the liquid. No, the trowel does not damage the waterproofing. You do not embed backerboard anywhere in your shower floor, in it or under it, so I’m not sure what you mean by your second question. The method you describe on the floor is completely acceptable, but there are things that are vastly different than traditional shower floor waterproofing, the drain being one of them. That method is described in detail in my liquid waterpoofing manual (for floors and walls).
Rog, sorry to be bothering ya a lot these days, well one last question, done the shower/bathroom tile project just finished grouting. Now I think I may have made a mistake, grout went in well and I hit every grout line with the butt end of a marker to give the lines a nice defined clean concave look. Now I foree no problems with this on the wall tile, I also did this, strike the grout lines that is, on the shower floor tile as well? could this potentially be problematic? Grout lines are one eighth inch. I feel I should have not hit the gout lines on the floor with the striker as I look back as water and dirt can pool here. the shower is definitely waterproofed thats for sure! If this was a bad idea, might I be able to grout over the lines or cut them out and regrout? Ah man! hope this isnt to big an issue!! Thanks Rog!
Hey Jake,
Unless the edges of the grout line are not at the same level as the face of the tiles it will be fine. It would take a huge dip to get water to pool in them.
If you have any more questions can you please post them here rather than three different threads? They all show up in the same place in the back no matter where you leave them.
Hi from Leadville!
Bought some of your guides, but didn’t see this addressed yet…
Say I’m a slow DIYer, and I want to do everything above my tub through the hardibacker installation stage, then take a shower (have a beer?), live life and move on to the thinset and tile a day or more later. I figured I could protect the substrate with some nailed up shower curtains… Is this okay for a shower or two?
Hi Katie,
Okay – you’re a slow DIYer.
I suppose if you needed to. Not really the best idea, but the real world rarely lends itself to the best idea, eh?
Hi Roger, can i use the mapei ultraflex 3 for the shower floors and walls over the redguard? i know its more expensive but since im using for the basement floor over other tile,just figured i would use the same everywhere. thanks
Hey Steve,
Yes, absolutely. Great stuff!