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 have a question about the 2 indentations along top edge of the shower pan in my master shower. I just recently had someone replace the silicone grout along the top of the plastic type shower pan where the tile meets it and the guy said that you shouldn’t cover the long little drain holes with the grout. He said the drain hole things are there to let air get up behind the tile to let it dry out if any water ever gets back there. The builder actually covered these indentations with grout so I’m not sure if he’s right or not. Is he?
Hi Patricia,
He’s right, to a point. It’s not to let air in, they are to let water out. They are weep indentations.
Roger, first thank you for guiding me through my shower re-do. Schluter installed and water test successfull, yes!
Time to tile. I read the tile install stuff, but have a question. I want to use some sort of a ledger at the bottom of the shower and make my way up. Thinking about a 1×2 or 2×4. My concern is drilling it to the studs through the kerdi membrane. Is that ok to do and if so how to repair the holes.
Thanks
Roland
Hi Roland,
Yes, you can use kerdi-fix or silicone to fill the penetration holes after you remove them.
I think I will go with silicon instead of the Kerdi due to the cost difference.
Also, I noticed my kerdi shower pan is not level along one of the walls, prolly cause i had to cut it to fit it in the shower space-drain not centered. My tiles are not going to be the same size at the bottom row. Any suggestions on how to proceed?
Thanks
Roland
Draw a level line one full tile up from the lowest point on the floor, then cut your entire bottom row to that line. That will give you a level base to stack the rest of the tile on.
Thanks Roger.
Roger,
Lots of great info here you’re doing us all a great service!
Question (try not to laugh) :
I am installing a new shower and my shower pan is now set (preslope, membrane, cement) I have extra red guard and want to apply it to the cement shower pan and lower walls before I tile it. I know it may be overkill, but is this ok?
Thanks
Hi Casey,
No, do not do that. You are creating a sandwiched mud bed between two waterproof layers which can lead to mold, mildew, and all sorts of nasty stuff. Overbuilding in a shower is not always a good idea. It’s waterproof – tile it.
I bought polished black pebble tiles (mounted on 12-inch mesh squares) to use for a shower floor. After reading the articles here, I just bought the Miracle Sealer 511 Seal and Enhance. Can I apply this to the pebbles before the tiles are laid on the thin set? My contractor is doing the installation, but I thought I could save time and money by applying the sealer myself ahead of time. Everything I’ve read says to spread the thin set, then place the tiles, then seal, then grout, then seal. Can I seal first, then place the tiles on the thin set, then grout, then seal? I’m going to use a dark charcoal grout.
If I want more of a wet look after I use the Seal and Enhance, can I apply a hi-gloss surface coating after using the penetrating sealer? If so, does that need to be done before grouting, after grouting, or doesn’t it matter? And in your opinion, would a hi-gloss surface coating eventually wear off during regular cleaning of the shower floor with a scrub brush? If I use the hi-gloss sealer before grouting, will the grout rough up the gloss surface? I might like the look when it’s fresh, but if it’s not going to last, then I probably won’t bother. Just wondering how durable a wet-look sealer is.
Also, my walls are going to be 3 x 5 standard white subway tile with white grout. Should the walls be tiled before the floor, or the floor first, or doesn’t it matter? My contractor has never worked with pebble tiles, so I’m researching before he starts. Any other advice specific to using pebble tiles? He should use a sanded grout, right? Thanks!
Hi Sara,
Yes, you can seal the pebbles first.
A coating is NEVER a good idea on a shower floor. Water is extremely abrasive, you will notice a wear pattern within three or four months. If you want a high gloss pebble – buy a high gloss pebble. The best thing to do with what you have is a couple layers of the seal and enhance once it’s all grouted.
With pebble tiles it’s always best to do the walls first then cut the pebbles to the walls. Yes, sanded grout.
Thank you! One more question: I’ve seen photos of pebble tile being used for the back of a shower inset (a niche for bottles, etc) and I’d like to do this in my shower. My contractor has already built the inset. Is there any special thing he needs to do to apply the pebble tile in this area, since it will be vertical, or should he spread thin set, then apply the pebble tile and press until it holds on its own? Thanks!
Hi Sara,
He doesn’t need to do anything special, it’s installed just like any other tile back there. He should know that.
My shower has tile walls but a solid floor. I am taking the grout out with a dremel tool and may went too deep in some areas, like into the backer board. Am I screwed?
Hi Todd,
Not unless your walls were topically waterproofed. If you only see gray backer when you dig into it, and not any type of fabric or rubbery membrane, you’re fine.
I am planning a bathroom remodel. I would like underfloor heating and am looking at a rectified tile to use thin grout lines. I’m seeing quite a bit of confusing information. Any advice?
Hi Kathy,
You’ll need to be much more specific for me to be able to help. I could write a book on advice for that installation, which I will do, but not tonight.
If you’re wondering if it can be done – absolutely. I do it all the time.
How high is the kerdi to go up wall in a shower ? Is this a plumbing code issue and/or a building code issue?
M
Hi Edward,
In some places plumbing, in some building. Regardless a minimum of two inches above the shower head covers either.
Roger,
Attempting first shower install ( 3′ / 3′ ) for a friend. She wondered since the existing tiled floor is structurally sound ( and I did inspect it, and appears sound ) if I can chip out old ( 2″ ) tile and replace woth new. I have read some articles on this, but after reviewing your articles I would trust your recommendation. Thanks in advance!
Joe
Hi Joe,
Yes, you can. Provided it is not a topical membrane on the floor which would be damaged when you remove the tile. If it’s nothing but gray deck mud directly beneath the tile you’ll be fine.
I’m adding tile above a fiberglass shower stall. There is a 1 1/4″ flange at the top, and one of the three walls is an exterior wall with a sheet of plastic on it going behind the flange. I assume that the plastic is tied into the shower base, but I honestly have no idea. Because of this, I’m really unsure which waterproofing method to use.
Should I use the traditional method and tie the plastic sheet to the flange of the shower stall? Should I use a topical method and cut slits into the plastic sheet on the exterior wall? I really don’t want a mold sandwich.
Hi Nathan,
Neither, above the shower head you can just bond the tile to the wall without worrying about a barrier.
I bought a home and had the bathroom gutted out.
I will be honest I do not know much about contracting.
So, it seems the people I hired took some shortcuts. Shame on me for not being more knowledgable at the time.
I had the tub taken out, and asked they build me a stand in shower, tiled all the way around except for the ceiling and tiled the shower floor.
The walls seem to be doing great. The shower floor however is not. I asked them if I should buy a pan to have it installed so that they will tile over it (was looking at do it your self videos and saw the redid-pan). I was told I didn’t need it. I saw them pour concrete and build a base, they then tiled over it.
One year later, the grout was cracking on the shower floor, it became dark in some places, and the floor appeared not level.
Water pools in great amounts near the drain, I have to use a water scraper to move it into the drain. It remains damp. I need to mop it up with a huge towel after a shower.
I had someone come re-grout it. He added more caulk to the perimeter saying it is likely that the shower is leaking through the base and walls. He also told me that the drain does not seem to be perfectly aligned.
6 months later the grout has cracked again and in more places. I see thin cracks all over the grout on the shower floor. I wish I never had them take the tub out.
Can I put a ready shower pan over this tile to ensure all the water goes straight to the drain? I am thinking like a plain white shower pan that does not get tiled. Would I have contractors lay cement or thin set or …sorry….and put the pan over it? Is that even possible?
Or would you recommend I have someone pull all the tile up, destroy part of the wall and re-install a tub?
I worry that if I keep it this way, one day the bathroom will fall through the ceiling in to the basement.
Thank you in advance for any advice you have to offer.
Hi Aby,
If they used ‘cement’, rather than deck mud as you stated, that’s the problem. It’s very likely since your floor obviously is not sloped correctly. Your best bet is to hire a contractor who knows how to build a damn shower pan – yours did not. They work just fine when properly built.
Roger : Honestly, I have had nothing but coffee.
Located a linear drain by AOC – Miniklassik grates- Pt # 95165
Have you any experience with this product ?
Do you know where I might obtain same ?
Thanks, Murray
Oh, I’m assuming this is the drain you mean? Never heard of it, nor used it. Google is likely your best bet.
Any idea of where to obtain this linear drain? Thanks, Murray
Hi Murray,
As you have not replied to a specific comment I have no idea what linear drain you may be talking about. I also have over 30,000 comments here (seriously), so it is nearly impossible for me to search through them all.
If you would reply to this comment with the specific type of drain I may be able to help.
Roger : Sober now. Shower, 3′ x5′ on coloured patterned concrete, on grade slab, radiant heat. Want to use a 54″ to 60″ linear [trench] drain along the back wall. Can this be cast in place ? Can I install the trap 5′ from the end of the shower – for access ? Alternately, put the trap at the end of the drain and clean out, if necessary, with a wet vac ?
What, if any, waterproofing should be applied to the concrete ? Murray
Hi Murray,
Yes, it can be cast in place. Yes, you can place the trap there or at the end of the drain, wherever you want it. A topical waterproofing is always easiest with linear drains – and YES, you need it.
Dear Awesome Floor Elf, We are nearing the end of our laid back shower installation . We have the mini subway tile up (above the cast iron shower base) and are about to start grouting with the Fusion Pro bright white between our very white mosaic tile. Now that I have bought the Fusion, I got round to reading the installation instructions. Like a good little student elf, I have followed your instructions about substrates and the change of plane. The manufacturer of Fusion says to NOT use this grout in the change of plane but to use silicone instead. I picked this grout out because of the need for less maintenance and no need for sealing. Is using silicone in the corners going to cause problems with mold or mildew? Is there anyway to apply this Fusion in the change of plan that will prevent a problem. We have used multiple coats of redgard over the hardibacker and used the fortified mortar that cures by chemical reaction, not evaporation. Please advise any choices if any that we have. We are old and battling Father Time so maybe silicone will outlast us. We are very proud of our shower and we owe it all to you. I got a few quotes and was able to see right through the workmen’s plans for installation. We had to do this ourselves. Big hug and kiss! We love our new, in progress, shower. Sometimes I open the bathroom door just to look at it again.
You need to use silicone in the changes of plane. They will move in different directions, the grout can not handle that, silicone can. There should not be any problems with mold or mildew.
I had decided on the traditional method of waterproofing.
I installed the poly to the studs , and then silicones it to the tub.
Now as I am preparing to tile I noticed pretty much ALL of the poly has come unstuck from the silicone. This,actually blew my mind as silicone is a real pain to remove, unless of course it is silicone to poly.
What should I do? Silicone doesn’t stick well to silicone so I don’t know if it’s a good idea to re silicone everything.
Maybe I should abandon the traditional method and switch to a kerdi tub surround?
Hi Brendon,
If the silicone doesn’t stick well to your particular poly you can use sika-flex, which is a urethane based sealant sold in the concrete aisle of any big box store. It will bond to everything.
I have some unused PL premium. It’s polyurathane based. Will that work?
Yes.
Roger: Still planning on the floating slab, with patterned surface. Floor in shower area sealed and sloped 1/4″ foot to drain Walls cement bd joints fiberglas tape and thinset with corners caulked. 2×4 ps sill plate wrapped on bottom and inside with 6 mil caulked to the floor and the 2×4. 6 mil vapor barrier caulked to sill plate, cb caulked to sill and floor, tile installed with thinset, corners caulked, 1/4 gap with 2 – 1′ drain holes in each wall, thru to vapor barrier. Any moisture migrating thru the concrete should evaporate, assisted by the in floor heat.
I’ve installed a custom shower base, about 3×5 in my bathroom. I plan on using 3 inch square tiles for the base. I have siliconed these together with two small beads and 1/8 spacers to make 12 inch squares for easier installation. My question is what impact will the silicone have on stability and strength with the thinset when dried? Should I overdo the thinset thickness or go with the norm?
Hi bh,
Unless you got silicone on the bottom of the tiles it won’t have any impact at all. Install them normally.
Hi Roger,
I’ve installed kerdi-board around a niche tub. The tub has a vertical edge and the board sits above it, with a small gap. I’ve filled the gap with kerdi-fix and glued a kerdi-band on top, as suggested by the schluter video.
I would like to install narrow horizontal tiles around the tub. You suggested not to glue the tile to the tub, however, since the tile is very narrow, the last row would not be supported at all if I don’t glue it.
Any suggestions?
Thanks,
Igor
P.S. I’d like the end result to be something like this (except that the tiles are rectangular):
http://cwremodelcontractor.com/uploads/3/0/2/5/3025096/2802029_orig.jpg
Hi Igor,
Put silicone behind the bottom row.
I am building a small addition 5′ x 10′ with a toilet, basin and 3′ x 5′ shower at one end. The floor of the whole addition will be concrete patterned floating slab with in floor hot water heat. I plan on stud walls for the three sides of the shower, 6 mil plastic vapor barrier covered with cement board, corners filled with silicon chalk, thinset and fiberglas tape on the horizontal joints. I plan on using pressure treated 2×4 for the sill. The shower floor will be part of the whole floor, sloped to the drain. How do I finish the plastic, cement board and tile, in relation to the wall and the floor ? The floor into the shower will have no barrier, allowing a wheelchair to roll directly into the shower. Is the bottom of the vapor barrier, the cement board not fastened to the sill and the gap not caulked ? Will water not be able to wick up into the studs ? Murray
Hi Murray,
In a correctly constructed shower there is absolutely no way for water to wick up into the studs, they are covered by the waterproofing membrane from the top of the wall down into the weeping system below the floor tile. Your shower floor, curbless or not, has to be a separate floor with waterproofing tied into the drain’s weeping system. Short of waterproofing the entire bathroom floor there is really no way to isolate the shower and waterproofing from anything else in the room, especially in the manner you’ve described.
We are replacing the tub in our bathroom with a shower. That being said – the floor area available is the size of a standard bathtub. We would like to have a bench seat at one end (tiled the same as the walls) but we plan on using a one piece shower base for the floor. Do we have the shower base go up to the bench or wall to wall so that it would run underneath the bench. It looks as though doing the former we would have to move the drain to the middle of the base, whereas the latter the drain would stay where it is.
Hi Sarah,
You would have the base go up to the bench, build the bench first.
Question about transitions from shower floor to wall and wall to wall. We were require to “float” the walls by the building inspectors due to possible soil movement. I understand your preference is caulk, which makes sense to me. Our contractor has the tile butted up to each other particularly on the floor to wall transition. I understand his comment that won’t see it because the caulk sticks to the tile, but what I am concerned about is the movement of the floor. How big of a space should we ask him for to allow the caulk to provide a little bit of flexibility? We were thinking of 1/8th of an inch.
Hi Lisa,
You need at least 1/16″ in there for movement accommodation.
Roger, I would really appreciate your advice on a tub installation—-
I’m assuming all drywall is done after the tub is set. So this means no drywall in the areas below the tub deck. Is that OK?
For slab-on-grade with wood framing—I need to install a heavy cast iron soaking tub (no shower) into a 3 sided alcove, with the long side on an outside wall. It will have a granite slab (or engineered stone) deck and front face–9″ wide deck all around. The plan is to use ledgers on the walls and add pony walls near the tub lip to support the deck (tub to sit on 5×5 tubing risers for desired height with no load on the deck support). Do 3 sides, then roll the tub into place with a pallet jack; level and tie in drain; then do the front face.
Questions:
1) Does this sound like a reasonable way to do this?
2)Should I install a 3/4″ plywood sub-deck for stone support?
3)Then 1/2″ cement board on top of that (and on the walls)?
4)CB on the walls up to at least stone height (2′)?
5)Then what? Do the deck & walls need waterproofing since it’s just a tub without shower. Note the simplified mfg. instal, guide shows none.
6)If water proofing is required, what would you recommend? Redgard? Kerdi membrane? I think I read on your site that either will stick to CB, but not to plywood—right?
7)So, now how to attach the stone to the waterproofed surface?
a) Thinset? If thinset, what thickness should I assume (to get support framing height correct)? Guide says to leave 1/16″ gap under tub lip.
b) Silicone caulk? I think I read that this won’t stick to either Redgard or to Kerdi membrane. Please confirm. I talked to one sub who was suggesting just a plywood deck,with no CB, and no waterproofing, and then silicone the stone to the plywood. He offered Redgard as an option (but does silicone stick to it?).–This sounds all wrong.
Hi John,
1. Yes
2. Yes
3. Yes, or ditra
4. Yes
5. You can use a topical waterproofing on them if you want, but it’s not really necessary.
6. Redgard or kerdi will work fine. They will both stick to wood, but the wood moves too much to have a stable installation straight over it, CB is the correct option.
7. a) Thinset at least 1/16″ thick after tile is installed. b) Silicone will stick to both, neither will bond to silicone. I know, backwards. Actually, the redgard will not bond to it, it will bond to redgard if the redgard is cured. Thinset used for the kerdi will not bond to it, but silicone will bond to the kerdi.
Yes, drywall after the tub is set, yes that is ok.
Roger, thanks for the response. Some follow-up questions, please:
1) Summary—
a) 3/4″ CD plywood deck screwed to the support framing; then 1/2″ Hardi screwed to plywood (screwed to plywood only or through to the framing?); 1/2″ Hardi on surround walls & on front face of tub.
b) Stone slabs attached to deck, front face of tub, and 2′ up the surround walls.
c) No waterproofing and no vapor barrier (plastic sheet).
2) I’m assuming that waterproofing is not required because only minimal water splashing should occur onto the stone surfaces, and whatever water penetration occurs into the stone or substrate should evaporate into the room–right?
3) a) Can I bond the stone to the deck with silicone?–essentially gluing it down. Or should I use thinset?
b) Same question for stone surround walls and face of tub.
4) a) I was going to use Hardi on the walls up to just short (1″) of the stone height so as to hide the seam under the stone, then go gyp board from there to the ceiling Do I need to use Alkali Resistant Mesh tape and thinset there or could I use ARM tape and drywall mud? The wall above the stone will be textured with drywall mud and painted.
b) Is the ARM tape required because of corrosion from the thinset or from the Hardi? In general, if it’s outside of a shower, can you tape Hardi joints together with paper tape and drywall mud, or must it be ARM tape with drywall mud, or must it be ARM tape with thinset? For outside corners in a bathroom, but outside of showers, should you not use metal corner tape?
5) a) Silicone bead on all joints around the tub–right? Stone to tub, stone to stone, stone to drywall.
b) Should I also silicone the Hardi wall substrate to the deck stone or would that create a potential water pocket between 2 caulk beads?
c) No weep holes–right?
d) What should I use to seal stone-to-stone seams in the deck (can’t install the deck in one piece). Is it OK to glue these together as you would for a kitchen island top or a vanity top? If not glued together, would you use grout? silicone?
1) I’m assuming you have thinset beneath your hardi on the floor, yes?
2) No, waterproofing is not required.
3) a. You should use thinset. b. Same answer.
4) a. You need to use thinset in the wet areas, you can use drywall mud in the dry areas. b. from the thinset. You can use metal in dry areas.
5) a.Yes b. No, do not silicone the hardi to the deck stone c. Right d. You can use any of those, it is normally seamed with epoxy like a granite countertop.
Roger, thanks for the great advice. Some clarifications, please:
1) Thanks for the thinset reminder. I Will use thinset between plywood deck and Hardi (to insure flat surface for Hardi).
2) Hardi screwed only to plywood deck and not penetrating through to the framing (for wood expansion reasons)—-right?
3) Is CDX plywood smooth enough for my deck? Will thinset fill any roughness/voids? I saw another post (about floors) where smoother plywood was recommended.
4) a)Can you use paper tape and drywall mud on Hardi joints in dry areas (H-to-H, or H-to-gyp)? Or must you use ARM tape?
b) My drywall guy insists that using ARM tape and thinset for Hardi joints will crack. His technique must be wrong. Is there an obvious explanation for what he might be doing wrong?
5) Should I use all this same tub-deck philosophy for vanity cabinet tops with backsplashes? Seems like the same animal.
Hi Roger,
We have found your website and waterproofing guide very helpful. I actually wish I had found it sooner in our renovation (luckily we found it before we hung 4 mil waterproofing AND used redguard). We have a few questions, but first, here is the background:
We removed a fiberglass tub and surrounds. We have installed an acrylic tub. So far, we have hung 4 mil waterproofing, durock and we have bonded the joints with joint tape and thinset. The durock only is where the former surrounds were (5 ft above the tub flange). 1) Should this be higher? The shower head hangs from above this level.
2) The greenboard that was above the former shower surrounds seems to stick out further than the new durock (we had measured it and were confident that it was 1/2 in, but now secured, they don’t seem to line up). Should we replace the greenboard with durock to the ceiling and if so, do we just hang the 4 mil waterproofing so it overlaps in front of the 4 mil waterproofing below it? Or do we need to (dare I ask) start over?
3) When screwing in the durock, there were a few times that I missed the stud. I’ve removed the screws, but is there a chance I punctured the 4 mil waterproofing behind it? And if so, does that mean we should start over?
We really appreciate your suggestions.
Hi Alex,
1. It should me a minimum of three inches above the shower head.
2. Replacing the greenboard would be the best solution. You only need the barrier to three inches above the shower head, but all the way up would be better. Just overlap it.
3. Yes, you likely punctured the barrier. It’s not a huge problem, though. Just go ahead and leave it.
Hello,
I couldn’t find anything on this anywhere on your sight, so I hope im not asking for something that’s already been answered.
We are doing a complete remodel on our 135yr old farm house and some things that my contractor is doing make me nervous! So, he is putting a shower in a bathroom that previously didn’t have a shower in it. I wanted him to do a mud base shower pan. He used #2 thinset…he built the frame, put a thinset sloped base down. Next he put the PVC membrane in. He put about an inch or so thinset on top of that with pea gravel around drain for weep holes. In the process of waiting for my tile guy, the thinset has cracked in several places. Is this going to be a problem? Should I have him redo it? One other thing, he did use aluminum mesh for extra strength.
Thanks for your time,
Jake
Hi Jake,
Are you sure it was thinset? (I have no idea what ‘#2 thinset’ is). He has the lath, preslope, liner and slope correct – with the pea gravel. It is all correct – provided it’s done with deck mud and not thinset. Yes, thinset will cause a problem. The cracking you see now is just the beginning.
After rethinking a shower installation (we took out the mortar bed and bought a Kerdi system) we were left with an Oatey rubber membrane on the plywood substrate.
–We placed the liner down first and put mortar on top which many people said not to do, so out it went. Should we leave this rubber liner under the new Kerdi foam base? Or will that cause the double liner moisture problem?
Hi Doug,
No, you should not. That creates an area in which moisture can get trapped and lead to mold. No reason for it at all.