Drywall and other bad ways to build a shower
Sometimes it’s nice to know what not to do when remodeling a tile shower in your bathroom.
Alternatively, it’s nice to be able to monitor the progress on your own remodel and see if the tradespeople are doing things correctly.
This post covers 6 mistakes that are too common in bathroom remodels.
1. Drywall Shower Walls
Drywall (sheetrock) falls apart when it gets wet. If you want a bad way to build a shower then this is it.
I should mention that there are a couple of companies that will warranty their waterproofing over drywall.
For example, Schluter approves their Kerdi Shower System over drywall in showers. The theory being that moisture should never penetrate the waterproofing on the surface.
So if you insist on tile over drywall in a shower then that’s how you “waterproof” drywall in a shower.
Please keep in mind that liquid waterproofing products are not approved for this purpose.
So, if you see your contractor applying Redgard or another “waterproof paint” over drywall you might want to put a stop to things sooner rather than later.
A properly built tile shower will have the appropriate backer board, waterproofing, and shower pan to properly manage water from the shower head and send it down the shower drain.
2. Not taping and mudding the seams
Cement board is 3’x5′. I’ve walked into people’s homes that had cracks in their tile 3′ high all the way around their shower. This is a result of the walls flexing and the installer not taping and mudding the seams.
Does your shower have a cement board or Hardibacker installed on the walls? If so, you’ll want the seams in your shower enclosure covered with alkaline-resistant mesh tape.
3. No waterproofing
I’ve covered this elsewhere but a shower should be waterproofed. You can either use a waterproof tile backer board, cover cement board with waterproofing, or install some sort of water-resistant sheeting behind backer board.
If there is no waterproofing then your shower is a likely candidate to have issues. Failure isn’t guaranteed, however.
4. Not replacing your old faucet
One of the problems with remodeling is that once you get started it’s hard to draw a line of where to stop.
Take a good look at where the faucet is in relation to your home. What’s on the other side of the faucet wall?
If it’s simply a closet or interior space then it could always be replaced from that side. Usually, this would include patching the drywall but otherwise isn’t too invasive.
If the other side of the wall is, for example, kitchen cabinets or the exterior of the home then you’re going to want to very seriously consider replacing the shower faucet while you have things opened up.
5. Tile mastic adhesive in a shower
Bad ways to build showers include bad products.
Tile mastic is a premixed organic adhesive used for sticking tile to a wall. It comes in a bucket and resembles glue more than a cement mortar.
There are very few situations where mastic is an OK choice. For example, you don’t want to use it:
- over cement board painted with Redgard or other liquid waterproofing
- over Kerdi or other waterproof sheet membranes
- to install tile on a shower floor
- to install glass tile
- to install large format porcelain tile
- to install natural stone tile
The only place it’s OK to use is when tiling in non-wet areas, over drywall, with small ceramic tile. Small subway tile on a kitchen backsplash is one area where it would be acceptable.
Otherwise, you typically want to avoid this product and purchase a proper thinset mortar.
6. Not doing a flood test
If your shower is going to leak, wouldn’t you rather know sooner, before it’s tiled, rather than later? Wouldn’t you like to know that your shower doesn’t leak before you make your final payment to your tile contractor?
A simple flood test will help to determine this.
Conducting a flood test does not guarantee that there won’t be any problems. However, most of the leaking showers that I’ve looked at could have been prevented if a flood test was done.
Consequently, I would write it into your contract with your tile contractor.
Why you should NOT buy a newly remodeled home
Bad way to build a shower- conclusion
Just like baking a cake, it’s the ingredients that matter. If you are paying for a new tile shower and see the things listed above, I advise you to start asking questions.
However, if you went with the low bid, you might not like the answers.
Is your shower already built? Then you’ll want to read this post:
LaNell, I completely agree about the sloping. Not familiar with what a divot drain is but standard 3 piece shower drains are still very commonly installed today and probably will be as long as the bonding flange drains stay 10x higher in price.
Thanks for your comments!
My husband built a tub surround for a 5 foot tub out of ½” in Hardibacker. He used 15lb felt paper behind the hardibacker board.
He wants to use fiberglass tape and mastic to tape the joints before tiling, we will be using an epoxy grout.
1. Should he use thin set for those joints instead?
2. What are your thoughts on applying Regard to the hardibacker before tiling? I have read mixed reviews about using redgard with a vapor barrier?
Thanks, and we appreciate the work you do on this site!
Hi Claudia and welcome back!
You guys definitely want to use thinset for the seams. I know it’s a hassle to have to mix it up but it’s much more superior than the mastic.
And if you already have the felt paper installed then the Redgard isn’t a good idea typically. However, if you have any benches, recessed shelves, or horizontal surfaces of any kind those will need the Redgard over them. Those types of things are extremely vulnerable.
My contractor used green board in my tub shower walls that were then tiled. He is doing my master bath now which is where I saw the green board going up. I am having him change to backer board. How bad is it that my other bath has tile over green board
You definitely don’t want green board in a shower- especially if it has a tile shower pan (like in the photo). But, frankly, it’s not as big of a danger if it’s a tub surround. The lower end is what typically gets the most abuse.
With this being said, I seems to me that green board isn’t even an acceptable product for wet areas any more. Most tract homes are using Denshield which is the cheapest/fastest gypsum-based backing nowadays. So if there’s something in the contract about meeting minimum standards, your contractor probably didn’t with the green board shower. This could give you some leverage to have it replaced if you chose to push for that.
John G says
I am building a new shower in my house from start to finish. House was built in the late 60’s. There was a mortar bed on mesh for the walls, mortar bed on floor & no liner. A hole rotted in the top of the cast iron p-trap. Water would not drain before coming out on floor. I may have a little problem with my new build. I have a brick curb that is 3 1/2 inches high on outside and about 2 1/2 on the inside due to my pre slope. I cut the liner prematurely almost flush with the top outside edge of the brick curb. I already have the drain cut in also. Can I use metal lath & mud to secure liner, then tile it. I know liner was supposed to go over top but messed up. I feel like I need to start over but want to move forward as well. I plan to use the corner dams as needed. Is my shower going to be too shallow after mud bed. My drain will have to be around ½ inch to ¾ since I did pre slope & used up some of my depth. I have pictures. Thanks in advance for any help.
Thanks, John G
Hi John, I appreciate your checking out my blog.
The liner definitely needs to go over the curb. You may be able seam a piece onto the existing part and run it over.
I would encourage you to check out the John Bridge Forum and start a post in the Advice section with the details that you have here. You can upload your photos as well.
They are better set up over there for these types of questions. I participate over the and will look for you.
Tim C says
I want to install a tile floor throughout the entire bathroom and use that same floor running under a glass shower without a curb like I have seen in some pictures. I have homelux gatorgold membrane for the walls and most of the floor? Is it safe to use greenboard behind the shower walls with the membrane? It says no concrete board needed???
Hi Tim, I don’t know anything about Gator Gold waterproofing and am not sure which product that you purchased either. Additionally, I can’t get any of their technical literature to come up.
But you do want the waterproofing to extend out past the shower glass and into the main floor. I forget what the specification is off hand but it might be 36 inches past? The seams would need to be sealed as well.
As far as going over drywall it depends on what their literature says. Schluter is one of the only companies that recommends it. Most don’t. I would rather see people put in a cement backerboard but you could always try calling their number that’s listed on their website. If you were to call it’s not a bad idea to ask them to put their instructions in writing.
Hi, i’m doing a gut rendo on my bathroom and want to know the best way to do the tub surround. I didn’t do a moisture barrier (heard bad things about trapping moisture & mold) and not sure to use Durarock, Hardi Backer Board (and Redgard them) or i heard there’s a fiberglass board but don’t know its name? Also, what’s the best way to overlap the tubs 1″ flange? Should I but the board to top of flange and tape/seal over it with redguard? Or should I fur out wall joist and let board hang over flange to tub ledge & silicone the space along bottom of board? Also, what’s best board to use for the floor over plywood bec I want to use 3″ mosaic marble tiles and heard its best to thinset them before screwing to stiffen floor and prevent tiles cracking?
For the floor, if you use a backerboard for the floor then you definitely want to thinset it down and then screw or nail it also. This goes for either hardibacker or cement board. Make sure to stagger the seams so 4 corners don’t come together in one spot.
For the tub surround I typically set the board on top of the flange and then you can redgard/mesh tape to the flange. Some guys will put a strip of Kerdi band along the bottom board/flange connection and then Redgard from there up the walls.
If you prefer to fir the walls out and set the board on top of the tub then that will work also. Probably a good idea to leave 1/8″ gap where the board meets the tub and silicone it.
Thanks for the questions.
Great site I am putting in a fibreglass shower pan should i drill and anchor it to the studs I am sitting it in a mortar bed under the base
Hi Dave, Thanks for asking but this is more of a plumbing question. For plumbing I recommend Terry Love’s site.
Tracey Doug's wife says
It is killing me, but my husband decided to add a shower to the tub in our historic house. He asked the guy at Menard’s what to do but didn’t read anything. I’ve seen many places to absolutely NOT do drywall.
So below, for the old marble tile, he’s caulking it up with a waterproof caulk. But he didn’t put any other waterproofing underneath.
For the new stuff above, he Redguarded the wall; not nearly thick enough, I didn’t think but I can put more on before we put anything else up. And he’s using vinyl backsplash–looks very cool. He’s using a waterproof caulk between panels and the adhesive they required underneath.
I’m scared to death we will be replacing our wall studs a few years from now. Have you ever seen anyone do anything like this?
Tracey, it’s hard to judge. If things aren’t done correctly it doesn’t mean that it’s guaranteed to fail. It’s probably best to watch for signs of water intrusion and hopefully this isn’t the long term solution for your every day shower.
I am in the of remodeling our shower, I have already put up the hardi board and paln on water proofing it using Redgard. Should I tape and compound the seam using the compound or can I substitute the Redgard for the compound???
If I understand the question correctly you want to tape and mud the seams (mesh tape and Thinset) first then apply the Redgard Waterproofing.
John Sampogna says
Hi Dave, I am removing a tub and building a tile shower. If I use HardieBacker as the underlayment for the shower floor, do I need wire mesh to reinforce the first layer of mortar I use to create the pitch? Thanks, John
I’d say it depends on what product that you want to use. A product like Mapeicem or a feather finish product I think could work fine on their own over the hardibacker. If you use drypack I think it’s best to use wire Lath. I’ve seen people not use Lath and things went ok though. The first layer just needs to slope .
concerned remodeler says
Should our contractor be using green board strips nailed to studs instead of furring strips to level a wall behind a shower surround? What about placing a 2×4 flat as the stud location that is going to hold a 5/8 ” frameless glass shower door? Studs must be no more than 16 ices apart per codes, correct? Thinking I am seeing things that are not to code.
I’m not crazy about the idea of green board strips for flattening a wall. Not to mention that seems like an extreme amount of leveling. But I also don’t know if there is a rule against it.
If the walls are out of plumb that badly my preferred way is to sister studs next to existing studs only make the new ones plumb and flat.
And you’re right, studs are typically 16 inches apart and there should be framing for the shower glass to screw into.
Sounds like the contractor doesn’t care or is cutting corners.
Hi I am moving into a new place, the shower is completely tiled, no shelves nothing.
what kind of product must I use when I am putting shelves in.
will silicon help
Hi, I am installing a tile shower using a pan liner by Oatley. Per the instructions I used top sand morter for the bed but I feel it is too thick. Almost 2″ at the farthest from the drain. By the time I put down the liner and add the recommended 2″ to 3″ more the morter will be as high as the curb. I can add another 2×4 but will the weight be an issue. The floor is 2×10 joist with a 15′ span. I still have to add backer board and tile over the entire floor as well as the shower plus 3/8″ glass doors. One older professional told me he didn’t put morter under the liner but instead put it directly on the plywood sub floor. What do you think? – thanks
Mortar has to go under the liner so that the bottom layer will slope to the drain.
It’s not unusual for the bottom mortar layer to be 1.5 inches at the edge. The top is typically 2 inches. As far as weight, I’m not sure what your house in engineered for but most somewhat modern homes can handle it.
The curb is usually there 2×4’s tall
We are in the process of putting in a new tiled shower and floor. The plumber messed up and put things on the walls in the wrong places, so after the tile was installed, he came back and removed some tile and moved some pieces. In addition, he hammered into the tile floor to remove some tile because he put the wrong part into the drain area and had to change it out. I still see a little bit of the blue liner but the red water proofing material and good concrete is gone. There is a lot of rubble and rocks next to the blue liner and white drain pipe. I can’t see all that he did. I’m concerned. The contractor is saying the tile person will fix it all. I think the inspector needs to come back. What would you suggest?
If youre concerned about it having the inspector coming back isnt a bad idea. At a minimum, I would run water in there and see if anything leaks out.
I would encourage you to head to the John Bridge Forum and start a thread in the Advice section about your project. Post some photos of what your drain looks like. You’ll have a good idea of your options at that point.
We rebuilt a shower and installed Durock. We then taped and mudded the joints with Premixed thinset form a big box store. We allowed this to dry for a few days and then covered with two layers of Redguard.
When the walls were tiled, we used regular thinset that we mixed ourselves.
Do you see this as a problem with the premixed thinset in the joints?
If everything appeared dry when you installed the Redgard waterproofing then I would think that you’ll be ok.
Adam finke says
I’m thinking of using the homelux gator gold also in a shower. I’m just not finding any about pre slope on there website or product information. Did you do a pre slope?
Hi Tile Guy….my friend hired someone to redo her shower. I got in to it with him today because it appeared wrong. He built out the walls to make the shower bigger, and the new section of the wall is 1/4 inch different from the original wall which he says is because one of the walls was set back further. Also he put about a 10 inch wide piece of regular blue drywall from the top of the ceiling down 10 inches, then only put the concrete board from the end of the drywall to the floor AND the drywall is 1/4 inch wider than the concrete board. So he just put tape and a giant amount of plaster at an angle to try and cover the large gap in the two products. This is all around the entire shower. Am I the only one cringing here? He got pissed and walked out. Is he doing it right or should we cut her losses and find someone else? How is that much plaster and regular dry wall acceptable and why would two different widths material be used for a surface to be tiled. He did say he will be using redgart, but still?! What are your thoughts?
There’s nothing wrong with drywall being around the top of the shower. The cement board should go at least to the shower head- usually around 6 ft high or so. My suspicion is that A)He’s using 1/4 inch cement board on the walls or B) that the drywall is 5/8″ thick. This is typical in multifamily construction. If it’s 1/4 inch cement board then that’s not good. It shouldn’t be used on walls. If it’s 5/8inch drywall then he simply didn’t do the work of shimming out the cement board the way that he should have.
Also plaster shouldn’t be used on cement board-to-cement board seams.
Timothy Gomoljak says
Hi, doing shower remodel, have installed new shower pan, next, i will install 1/2 hardi backer brd., can it sit on top of pan flange(w/1/8 gap), so I don’t have to fur out walls, if i fur out shower walls, they wont match up to rest of bath walls. if i can sit on top of pan, how do I seal, caulk pan to hardi brds? use kerdi band?(i know about caulk, dont know about kerdi band) Thank you, Tim
Yes, you can install Hardibacker above the flange like you mentioned. Using Kerdiband is probably the best way to seal around the bottom. Use Kerdifix (sealant) to stick the Kerdiband to both the tub flange and the hardibacker. You’ll have to cut a small relief cut in each inside corner for the tub flange. I usually just fill the cut with more Kerdifix to make sure it gets sealed.
If you are going to use a liquid waterproofing over the surface of the Hardi board I would typically install that first before the banding. It could be done in either order, however.
I have a tile shower with backer board but have had an issue with my tub and removed it and can now access the back of the shower and can see the rubber they used for the floor on the shower. Between the rubber and the backer board it looks wet and is black if you pull it back it doesn’t go any further like it is wicking up the wall.Should I be concerned or is this normal the shower has been there for eight or ten years. Thanks
It sounds like the moisture is contained inside the liner- which is good. But I don’t know that things should be black which would indicate mold.
But if things are contained I don’t know that there’s anything to panic about.
Thanks for your help
I am having a new shower put in. I had the walls done in the Green Board because I wasn’t going to do tile. I now have decided to do tile. I talked with the contractor and he is planning on installing backerboard over the Green board and then applying MAPEI Mapelastic Aquadefense Indoor/Outdoor Membrane to the backerboard before laying the tile. Is this adequate? I have an DreamLine Slimline White Acrylic Shower Base installed already.
I don’t care for the idea of putting in cement board on top of the drywall. I think the way to do it would be
1. Remove drywall and proceed as you’ve outlined; or
2. Go over the drywall with Kerdi.
Schluter recommends their Kerdi product over drywall. It would be faster and easier than the way the contractor wants to do it and probably the most logical step forward. They have easy videos and instructions online if he’s not familiar with the process. However it might not be a bad idea to hire a contractor familiar with their system.
Don’t use the AquaD or any other liquid waterproofer over the drywall. It’s not the same thing.
Hi Tile Guy, I need to fir out my studs 1/4 inch so the cement board will cover the shower pan flange. What is the best material to use for firing strips?
My wife and I have a new construction home that we have been living in for less than 3 years but we are past warranty. We recently had a concern that there may be a leak in our upstairs shower (which is a shower only, fiberglass floor btw). After knocking out 3 tiles (FYI the cement wall behind the tiles got knocked out too because it’s all glued together) so that we could see behind the shower wall, we discovered that it was a false alarm, no leak, everything is OK. Good news! That said, now I need to replace the wall and tile we knocked out and this has created a new concern for me.
The original wall that was untouched is still behind the original tile that was untouched. As a result, when I cut a new piece of wall to replace what we knocked out, I am going to be creating a new seam in the wall that wasn’t originally there because now I will have new wall butting up against old wall behind the tile, make sense? And since the tile is still glued to the old wall, there’s no real way for me to tape/mud/waterproof this new seam that’s being created.
So I guess my question is… 1) How worried should I be about this seam? and 2) what’s the best way to repair this short of knocking down the entire wall and rebuilding it from scratch?
Probably 1/4 inch furring strips would work but you’ll want to make sure your screws are long enough to get into the actual stud. The best is probably to sister studs onto the existing and stick them past 1/4 inch.
I think I understand the question. What you need to do is to create a square or rectangle in the tile. So you need to carefully remove enough damaged tile so that you have a rectangle that you can repair. Here’s the tricky part: there needs to be 1 inch of cement board around the perimeter of the tile. For example: you want to repair four 6×6 tiles. Four 6×6 tiles in a square makes a 12 inch square. You need 1 inch of cement board around the inside of the tiles. So you would have a 10 inch hole in the cement board.
If that makes sense- you then patch the cement board with a 10 inch square piece. Patch it with wood behind it like a drywall patch (you can look this up on youtube). Then use 2 inch mesh tape on the seam and thinset. Reinstall 4 new tiles.
Hopefully that makes some sort of sense. Maybe this would make a good post some day with photos.
we are tiling a shower-bath that has a floor-to-ceiling wooden cabinet at the far end of the shower.
the contractor (who has admitted he had no idea what he was doing) glued and screwed plywood to the cabinetry (to support the weight of the tiles) and screwed that backer board into the plywood.
we are now having tilers fix what he did (he messed up the tile kitchen floor, so we hired tilers to avoid mistakes in the bathroom).
(1) should we remove the backer board from the plywood and cover the plywood in kerdi or other waterproofing material before re-placing the backerboard?
(2) assuming the plywood is covered by a layer of backer board which is in turn covered by the tile itself, how do we edge the tile to cover up the backer board and plywood behind it?
You could simply install a waterproof membrane over the backerboard. Something like the Kerdi membrane or one of it’s competitors.
For the edge, you’ll probably have to install a drywall corner over that edge. You would finish the one edge to match the drywall and the other edge you would Kerdi over.
My contractor used sheetrock behind our shower. He did not use a liner or any other type of barrier/coating. He simply tiled right over the sheetrock. The tile is floor to ceiling. Should I assume there to be issues in the near future? Is it best to start over?
That’s definitely not the best way to build a shower. Many showers back in the 70’s were built with moisture resistant green board and tiled over directly. It all depends, but I’ve seen some of those last 20 years but many fail much, much sooner.
So, yes, it’s best to start over, but that doesn’t mean that failure is a month away either. It’s probably best to keep an eye on it and plan for a redo in the next year or two.
Hi Drew and diytileguy- I agree that’s not not the best way, do you think a sealer applied over the tiles abd grout would help? I’ve wondered abut this if it might have saved my shower too, was too late when I came across mine though…
Sealer certainly can’t hurt things, in fact it’s only going to help. But you really don’t want that to be the sole strategy for keeping water out of your walls.
I understand that you mentioned that it’s too late for your situation. But that sort of a fix is short term, at best.
It’s best to not think about tile and grout and sealer as the waterproofing system. The goal should be to make the tile substrate- the walls- waterproof prior to installing tile.
what is your experience with red guard as a pan liner or any other surface bonded liner for a shower pan? I don’ have a good feeling about these types of shower pans.
Had these guys do what I thought was the pitch base. problem is it is level with my top height of backer board for the tile on the floor out side the shower. ( let me note this is a barrier free shower no curb) as I understand and have helped with pvc liner years ago another layer of mud base goes down first. since it is barrier free should the liner be over the 1/2 plywood build up for the floor out side the shower at least 2 inches opposite of the drain with the top mud base over that part of the liner as well before backer board goes down and tile?
these guys did cut out the 3/4 sub floor and lowered 3/4 put tar paper down and wire mesh before the mud pack. I don’t think a liner is in there and a top base,since it was done in one day.I need to investigate in depth before proceeding further, I am thinking I can grind down the humps and lumps to get it smooth with a diamond cup grinder to solve that part of the problem. no liner means taking it down at least 1 ” and cutting back to the drain weep holes as those would be filled with mud base. or just starting over completely since I will damage the paper and mesh.I could see using red guard as a another save guard on the top mud base before setting the tiles . I am getting two different ways of pan application from two different tile guys. I am a contractor as well, but I have limited pan experience and have done tub surrounds in tile and floors I know these pans have to be done right to eliminate any and all chances of water penetration.
let me also note my primary contracting is carpentry and this shower is part of a 1400 sq ft addition and remodel project. Can you help in any way to help my direction in this matter?
It sounds like this is a problem. But first off, I’ll get into the shower pan.
What you are referring to is two different ways of building a shower: 1) the pan liner (water in-water out) method; and 2) the bonded membrane method. Either one of these is an ok way to build a shower. My personal feelings are not in favor a liquids for shower pans but I do know that they can, and do, work when done properly.
However, for your shower, that is the advisable way of building it simply because it’s a barrier-free shower. The problem with pan liners is that there’s no good way of waterproofing the area where the shower turns into the bath floor. But with a bonded liquid, you can just waterproof over the seam.
What has me worried about this application is that it sounds like they only lowered the floor 3/4 inch which isn’t enough. You need 1.5 inches of “mud” (drypack) at the thinnest spot- which is by the drain. If you don’t have that then the shower will crack over time. It doesn’t matter if there’s liquid waterproofing over it, or not. I’m also curious what kind of drain is used. Is it a standard 3 piece clamping drain that would be used with a shower pan liner?
If so, there should be a depression, or a divot, around the drain. Not sure if yours has that, or not.
You can install a barrier free shower system with a 3/4 inch drop but you have to use a prefabricated foam pan. I like the Wedi Fundo Ligno for this. They have details on how to set the shower up from there.
Anyway, hopefully this has been helpful and please let me know if I can be of further assistance.
We recently had a bathroom tiled including the ceiling. We had to replace some ceiling tiles, then someone pointed out that there is “breathing space” – the ceiling board behind the tile flexes a bit (sagging downward). Is that because the ceiling tile is too heavy and pulling down? Is there any way to correct this without removing all tiles? We currently have center strip of tiles off (due to other repair), Is it possible to reinforce from there?
It’s hard to say but it could be that the ceiling backing is really thin? It could be that it’s a flimsy material? It could be that the spacing of joists are too far apart?
You might be able to cut a section out and install some sort of backing or framing to stiffen things up.
D Williams says
I cant seem to find a source for why you can’t do this…So my friend had an acquaintance hook up her shower plumbing on a shower remodel. Imagine my surprise to to see that the acquaintance had attached all of the plumbing into the backer board,not into studs or other cross pieces. My friend just can’t seem to understand why you can’t screw something or mount something directly onto backer board. Especially if there’s nothing but tile and thinset on the other side of it. The acquaintance had also used copper clamps with steel drywall screws to attach to the backer board setting the whole set of connectors up for galvanic corrosion (also called bimetallic corrosion).
I’m sure that you’re right on this but I’m not sure of where that would be written either. This probably falls more into plumbing code than anything.
You might try Terry Love’s plumbing forum. Those guys would probably know right away.
I’m currently having a shower remodeled. I’ve discovered that the contractor didn’t use any waterproofing on the Hardy backer before he started tiling. And to make things worse, he used Wedi Joint sealant to adhere the tiles to the walls. I’m so angry and wondering if I’m going to have to redo this shower.
I think you’re instincts are right and that’s not the way to build a shower. I think you’re going to have to go backwards a bit before moving forward again.
But at least you investigated and listened to your intuition. A lot of people get further down the road before they realize what went wrong.
Green board and drywall is all molded (black). This stuff is coming out today. What goes back up to waterproof the bathroom?
I have two posts that may be helpful to you:
One is my shower waterproofing crash course
And the other is on backer board
Both posts are accessible through the slider on the main page.
I apologize! I totally skipped the links.
Not an issue. I appreciate your reading my blog and participating.
Paul Potenteau says
I have new 9′ 1.5″ drywall on the shower wall with the window. The rest (3 sides) hasn’t been put up yet. Is okay to continue putting up drywall in the shower area because I will be using the Schluter Shower System Kit and Kerdi membrane? There is no 15 felt paper behind the drywall with the window.
Also the inside wall with the shower door will have a niche with exposed backside of drywall. How should I go about building it with Kerdi membrane or something else?
Paul Potenteau says
Okay, I found the post for the “How to build a niche from scratch” Thanks DTG
You can install drywall in the shower according to Schluter. However, I recommend installing a tile backer board because I think it’s a more sound practice.
Good! Hopefully that’s helpful.
Hey tile guy. Great reads and VERY informative for a novice like myself. I believe I made a bit of a blunder and could use your help overcoming it. I used the good proof system. Prepitch then 40mm membrane then quick pitch. I left a 1/4” at the bottom of 1/2” Hardie backer but during the “quick pitch” step I mudded to the top of the sticks, which means I mudded up the hardie boards about 1.5” I notice others have left enough of a gap for the boards to hover just above the finished bed. I’m wondering if this is a big deal, being that the hardie backer and mud bed are likely bonded at this point. Would it make sense to add another 1/2” hardie backer right over the existing 1/2” boards? Or would that be overkill?
I didn’t put a water barrier behind the original hardie boards either. Should I redguard the outside? Or maybe, if I do add additional 1/2” boards I can sandwich a waterproof barrier between the two?
Technically, you’re supposed to leave Hardibacker above the mud bed but there is an advantage to embedding it in the mud bed: it keeps the bottom of the board from moving too much.
The concern is that Hardibacker will wick moisture from the mud bed up the walls of the backer board. This is a legitimate concern.
But when I was doing this style of shower I would always embed the backer board into the mud- even if it was Hardibacker.
So, I think your ok the way that you have it but the proper way would be to remove the Hardibacker and redo the mud bed.
You don’t need anything behind the panel if you Redgard the surface.
Tim M. says
Thanks for the reply. I’ve got one more for you if you don’t mind. When I did the curb I kind of rushed through it (dumb I know). Now there are a few spots that are rather thin and you can still see parts of the “Kirbperfect” plastic. I’m trying to decide how to overcome these thin spots. They may be the size of a quarter or two. Should I just apply the thinset a little thick?
If the spots are small then I would think you could just use thinset to flatten them out like you mentioned.
lawernce israel says
can I use 1/2 pvc board as my sub board on my bench seat prior to putting down my durarock?
I’m going to guess “no” but with an asterisk in that I’m not certain that I completely understand.
I’m not sure what pvc board is or what the purpose it would serve? If its use is as a waterproofing then wouldn’t you just nail through it when attaching cement board?
If it’s purpose is structural then I’m not sure why one wouldn’t just install plywood?
Please let me know if I’ve misunderstood the question. I appreciate your participation.
Cindy Wagstaff says
My contractor installed densheild covered with Redgaurd, but only just to the halfway mark on a half wall which will hold the glass shower wall. He did use red guard over the drywall for a few inches past that. My question is, the glass company is suggesting I push the glass wall to the edge of the halfwall it will sit on (with a granite topper) so that we have more of an ledge for shampoo bottles, etc. however I know that this will have an inch or so of the drywall inside of the bath enclosure, even though it is covered with Redgaurd. Should I let them? Or should I have the glass sit directly down the middle of the granite halfwall which will mean only densheild is in the shower enclosure?
Redgard over drywall isn’t approved. That doesn’t mean that it wouldn’t work but it’s a pretty big problem if something goes wrong.
Particularly concerning would be how the glass company intends to attach the enclosure to the half wall.
If they intend to drill down horizontally and attach an anchor then I definitely wouldn’t want this done through drywall.
It’s up to you, the contractor, and the glass company whether you want to take the risk, it not. The safe thing would be to have the enclosure over the tile backer that’s waterproofed.
Is the risk really worth it just to set a few more shampoo bottles in the shower?
Hi Tile Guy,
Our contractor built a shower wall for us out if cinder block. He then covered that with Durock and on top of that, cement backer board. I am getting ready to tile soon. What do I use on the seams before tiling? Also, how do I seal the edges of the pony wall before tiling?
Also, is it ok to use a premixed tile set on the cement board?
I think the backer board is that hardieboard
I’m not clear on how this shower is set up so far.
It sounds like the shower is: cinder block then Durock cement board then more cement board on top of that?
If so, that makes no sense to me.
Cement board of any kind shouldn’t be attached to cinder block. Why not tile directly over the cinder block? Was the cement board screwed into the cinder block?
As you can tell, I have a lot of questions. But it doesn’t sound like this shower has a proper foundation by what’s been described.
I was mistaken. There’s just hardie board screwed onto the cinder block
Hardibacker shouldn’t be screwed into cinder block. The best way to attach a backer board to concrete is to use one of the foam panels like Wedi board, Kerdi board, or something similar.
Those can be glued right to cinder block and are also waterproof.
That’s probably the best way to move forward with the set up that you’ve described.
I’m remodeling a large shower after a leak.. It’s located in a corner and enclosed with glass – on one side a large panel sitting on a footrest/short wall and on the other a small panel and door. I am reusing the existing glass panels. Both panels were fasted to the bottom (and sides) with screws through hardware. This seems problematic to me, as I assume the screws would puncture the liner. How does one normally attach glass panels at the bottom without damaging/screwing through the liner/waterproofing?
Also, thanks for your very informative webpage, I’ve learned a lot here!
Ideally, the panels are screwed in only on the sides and not the bottom. Although sometimes they have to be screwed into the bottom- especially if it’s a pivot hinge.
Usually, what they do is use U-channel and silicone it underneath. The verticals would be silicone and screwed into the sides about starting about 3 inches high.
All the penetrations should be filled with silicone.
Another option would be to build the curb and half wall out of 2 inch foam, like Wedi board or Kerdi board. The advantage of this is that punctures into the foam won’t hurt the waterproofing as the foam itself is waterproof.
However, foam won’t grip the screws very well. If this is an issue then something could be embedded into the foam such as aluminum or plastic where you want the screw points at.
Kim Hudlow says
Hello! I am remodeling a shower/tub, and want to install 4 x 16 polished ceramic tiles on the long wall, and I hope to contrast them on the head and foot walls by using a 8 x 32 porcelain (floor) tiles for a decorative effect. The rough dimensions of this space are 34 by 60.75. What offset would you suggest on each wall? Do you foresee any problems with this design?
A 33% maximum offset is what is recommended in our industry. Obviously, if you are the end user and want a 50% offset then there would be no problem with that. These recommendations are from a functional/installation standpoint and not from an interior design point-of-view.
Sharon Coffman says
Hi! We are renovating an old house but also added on a new master suite with handicap accessible roll in shower. We have 10’ ceilings to match the rest of the house. My question is: how far up the wall do we tile the shower cavity since it is open & exposed to the rest of the bathroom, and how far into the room is absolutely necessary?
The tile only needs to be about the height of the shower head typically. In the older homes, it was only 5-6 feet high a lot of times. You don’t have to go all 10ft if you don’t want to.
How far tile needs to extend outside the shower and into the bathroom would largely depend on the circumstances, I think. Being a barrier-free shower you would obviously want not just the floor tile to extend out past the shower but also the waterproofing underneath. The industry standard is for a minimum of 12 inches outside the high point of the shower.
On walls, I’m not sure there is a standard. You’ll have to use your judgment and take into consideration how big the shower is, where the water outlets are, and if it’s enclosed, or not. I think a wainscot that extends outside the shower would be a good idea to consider or at least tile base with waterproofing that flashes up the wall.
Mark Hohider says
HI, I built shower with contractor in 2010 the tile has since cracked and I removed they were 12X12. The shower is 4′ by 6′ and sits on 2×12 floor joices at the end of the house not the center so it should be strong enough. We put a liner under the concrete which is a few inches to 2.5 thick. The reason the tile cracked is that the concrete did under it, I can’t remember if its just concrete I do not think it is it may be some other water proof stuff for the shower. Anyhow, should I address these cracks which are a few feet long and thin in width there are only 2… One site said to use Latex with Think Set and Fiber glass tape over the cracks with a nice smooth coat over the Fiberglass tape before the thin set to place the tile new tile on. Concrete cracks with a structural defect or without in my experience, please advise thank you.
It sounds like the concrete is the shower base? If so, I would replace the base. It may not be thick enough or maybe there is something else. But the cracks are likely to transfer right back through to the new tile so replacement is the way to go.
Hi, im currently tiling around the walls of a free standing tub. I’m using Hardibacker and currently skimming thinset over the mesh tape seams. My problem is I have completed all of the seams but on the last two I had to open another bag of thinset and it wasn’t until I was well into skimming that I realized the product was not acting the same. I looked and found I was using bed mud mortar. Do I need to cut and scrape away these seams, or will that hold well enough underneath the thinset I will be using underneath the tiles?
I don’t think that product works the same. I would remove those areas and redo.
I am redoing my tub surround. Currently there is drywall, a decorative board and a chair rail all around the bathroom. On one end of the tub the wall is flat, the other end the wall turns a corner. I’m wondering if the cement board needs to go all the way to the ceiling and to that corner on the one end of the tub? I am planning on tiling to the ceiling. I’m not planning on redoing the rest of the walls just the tub surround. Also what’s the best waterproofing method?
Cement board should be installed to the shower head height, at least, and going all the way to the ceiling is OK also.
If you don’t want to “wrap” the tile around the corner then you’ll need to keep the metal drywall corner that is on the corner intact. You can install cement board up to it and nail it into the board. The metal corner is underneath the paint.
For waterproofing, I recommend my shower waterproofing post which covers the different methods and products for waterproofing a shower. There are different factors to consider such as your application, access to materials, budget, etc.
Edward Maloney says
I have had a hard time finding a consistent answer to the question whether you can/should attach cement board over existing drywall for a shower enclosure. I finally went directly to Hardee company (Hardeebacker) and got this email response:
“You can put our product over dry wall. Just increase the length of the fastener the thickness of the dry wall. We do not require our product to be waterproofed, nor do we require a weather resistive barrier be used. There are some building codes that will require the weather resistive barrier behind our product.”
[Edited to remove personal information]
It’s my understanding that most companies won’t approve that application but going directly to the manufacturer, like you did with James Hardie, would be the way to go.
Sounds like the Hardibacker people will bless it.
Is it safe to tile over OLD sheet rock? Not the new sheet rock but the thick hard stuff.
I think you are taking about plaster. I think so. The problem that you’ll run into is that the plaster usually isn’t flat enough.
Dave G. says
I am just starting to demo out my tile shower that had cracks in the tile at the base and leaked water, but not out of the pan thankfully. I am finding out the original builder installed the pan to the studs, installed normal drywall over top, and then cement board. The water evidently wicked up the normal drywall about 2 foot and mold was evident. I am assuming they should have never put normal drywall inside the shower pan due to this reason and should have attached the cement board only? I am new at this, but I am noticing several issues with what the “professionals” did when they built the house.
You are correct. The cement board should have been attached directly to the studs or the studs could be shimmed out, or sistered onto, to build the framing out.
Additionally, there should have been some sort of moisture barrier installed and it doesn’t sound like your shower had one.
Hello. In the bathroom that I’m tiling, guys who did the drywall didn’t install it in 90° vertically. So my question is; if I level last two rows of tiles (40x80cm tile, 11mm thick) with an adhesive (20mm) it will weight around 52 kg per m² with this tiles, while limit of a drywall is 32 kg/m². What can happen if do this?
There’s a 5 rows all together, 2 meters.
If you are exceeding the limits of the drywall and it were to fail then I suppose that it would give at the weakest point which is probably the paper face.
If recommended removing the drywall and reinstalling it so that it’s shimmed out properly and you don’t have to build it out with mortar.
I am having a bathroom put in my basement and remodeling my master bath. They just put regular sheet rock behind the tub/shower area that tile will be put over. The contractor said he is putting a waterproofing over the sheet rock before putting tile on it. I am not sure this makes me feel comfortable. Is this ok??
The basement bathroom has no window in it and concerned about moister build up behind the sheet rock.
It should be OK as long as it’s a sheet membrane. Schluter Kerdi and Durock tile membrane both are approved for drywall as a substrate. However, I’m not aware of any liquid waterproofing membranes that are approved for this use.
Your best bet is to find out which specific product that is to be used and look it up on their website and see if the manufacturer approves it for that use.
Lisa Bolton says
We have gutted our ensuite bathroom and will start the DYI rebuild soon. This is our second DYI bathroom. The original plan for this bathroom was to tile the ceiling just over the shower but now we are considering tiling the entire room ceiling for look and consistency with tile. I found a procelain tile that looks just like a stamped tin ceiling that I like but the tiles are 13×48 and I am concerned about how easy they will be to cut and install overhead. I have also seen (much less expensive) options to install styroform tile that would have a similar look, but I am concerned about the potential for mold/mildew and the longevity of using a stryofoam product in that application. And whether styrofoam is code-rated for bathroom applications. I live in Ontario, Canada. Any thoughts or advice?
Bianca Reeves says
I have a question that me and my husband are going back and forth about. When building the shower pan liner I say not to use both a vinyl membrane and Redgard over that membrane. He says it’s just double the protection and it will be fine. I read somewhere that it will create mold in between the layers. What do you suggest?
I would check the stamped tin tiles and see if they are OK for a wet area. If it’s really a metal facing then they may be tough to cut. It depends on the tile.
The styrofoam tiles I have never seen but do the same thing and see if they are OK for a wet area. You don’t want the moisture loosening things up when you are showering underneath.
Don’t use Redgard over the top. I know it seems to be a “belt & suspenders” approach but it really isn’t. A mud pan shower with a liner is designed to have water drain down to the liner. Redgard screws that process up.
Do I have a problem, my house was built 14 yrs ago, we never finished the shower.
Its 23′ in length by 10′ with several 45 and 90 degree angles. It has 5/8 green board and the pan is hot moped.
Not being a tile man I put a vapor barrier, wire, and I am going to mud the walls and then Red Guard them because of cold joints. I can not mud the entire shower at one time, so I planned to stop at the corner and use screws into the existing studs at said intersections and cold joints, I would appreciate your thoughts on this.
If the walls are wired then that should give you some metal to tie things in with. I think the cold joint in the corner would be the way to go as it’s a natural movement point anyway. Seems like a solid plan.
John crisp says
Hi, so my membrane did great on the flood test for 24 hrs but I left it another day and noticed that some leaking had occurred around the drain. Should I be concerned?
Yes, if it’s leaking you should be concerned. The drain is a pretty common culprit so take a good look around there. Also, make sure the drain is well connected to the drain pipe
Jesse Holroyd says
Bad news do-it-yourself tile guy. There are 4 APPROVED methods for putting tile in a shower receptor in the state of California which has some of the strictest standards in the US and green board is one of them. I would never do it myself and have demo’ed green board showers that were dry as a bone but it is approved (it was on the test). As is installing tile over cement board which is what it’s for. BTW, you ALWAYS paper behind the cement board or whatever backer you’re using regardless of whether it’s waterproof or not.
I can see it if it’s a one-step float but I’d be surprised if they approve people sticking tile directly to the green board. The TCNA handbook speaks specifically about this method and says it shouldn’t be done. As you acknowledged, it’s not a good idea. As far as paper goes most product manufacturers say to use one or the other. But maybe this is a California thing? I don’t know.
I have shower stall I’m redoing. It now has a preformed acrylic base that we want to remove, and then we want to expand the shower. Doing so means I will encroach on a marble floor. Question is, can I build the new shower curb on top of the marble tile? To get to concrete would mean removing a portion of each marble tile, and I don’t want to risk cracking. I was hoping to drill through the marble tile and nail the wood down to the concrete floor plus glue between marble/wood.
I don’t see any issues with doing it this way.
Thank you for this forum DTG.
I am remodeling a shower. Demo’ed down to the studs and the concrete (first floor) slab. The old system was mud and mesh over felt paper and greenboard. It seemed to work fine for 25+ years.
I am keeping the existing cast iron drain that protrudes up several inches from the slab.
I have a hot mop crew coming tomorrow for the pan. Along the wall blocks (10 inches high) , they say that it will protrude about 1/2 inch from the face. I wall thinking of using 1 x 2’s for furring strips along this studs above this, but then thought to just use 1/2 greenboard sheets on the entire space above the pan. I plan to use durock cement board over the furring or greenboard.
I was told to use Redguard over the cement board and then tile directly to the Redguarded surface.
I am unsure about a few things…
Should I use furring or greenboard?
Should I use felt paper over the greenboard (or furring strips) instead of Redguard over the cement board. The felt would overlap into the shower pan and funnel water.
Is it wrong to use both? I keep hearing about a moisture sandwich but it seems the best way to ensure moisture drains into the pan. (Perhaps I am worrying too much about water, as the older system seems less waterproof and worked fine…)
I just saw your article on waterproofing a shower.. excellent. I guess that answers the question of not using two barriers.
In this case, I think I would fur out the walls then install the cement board and Redgard on top of that. It would basically be the same as doing a vinyl liner with cement board over it. Also, your cast iron drain probably doesn’t have weepholes and the newer ones do. It’d be nice to have one of the newer versions or at least drill some weepholes in your existing drain.
The hot mop was done a few days ago… holds tight after 24 hrs filled with water to the top of the threshold. It did not come out 1/2″ from the walls, so I will use drywall shims as furring as needed… perhaps an 1/4 of an inch at most.
I did replace the cast iron drain top with a new one.. yes, the old one was clogged at the weep holes. Good suggestion.
Thank you and Happy Holidays!
I’m not sure my last comment went through, so again I just wanted to thank you for your helpful advice.
I appreciate it and glad that this was helpful!
Lee Aimers says
Hello Susan. Check out “Go Shelf”. I have not tried it, but it looks like a great idea!
Hello, I recently used simple set for my kerdi band in one corner of the shower and along the bottom where the board meets the shower pan flange. Thank God I did some more research as I had found out that it’s actually a mastic!!!. So I took off the kerdi band and scraped and sponged off all the wet simple set that I could. There is however some simple set that has dried on my kerdi board thats a strip 8 feet down by 1 inch and some along the bottom. Can I just place unmodified thin set over the simple set to re stick some new kerdi band. Do you think it will affect the adhesion for the tile. They really need to rename the pre mixed thin set to mastic.
Hello, I recently used simple set for my kerdi band in one corner of the shower and along the bottom where the board meets the shower pan flange. Thank God I did some more research as I had found out that it’s actually a mastic!!!. So I took off the kerdi band and scraped and sponged off all the wet simple set that I could. There is however some simple set that has dried on my kerdi board thats a strip 8 feet down by 1 inch and some along the bottom. Can I just place unmodified thin set over the simple set to re stick some new kerdi band. Do you think it will affect the adhesion for the tile. They really need to rename the pre mixed thin set to mastic.
It should work but that doesn’t mean that it will work. I would encourage you to use Kerdi fix as an additional prevention measure just on the edge of the seam.
Most importantly, I would encourage you to flood test the shower and see if it leaks. That’s where you plug the drain and fill it up with water and let it sit for 24-72 hours.
Bryan Kolano says
Hi, I’m going to tile a tub/ shower to the ceiling. I have hardiboard on the walls, all seams taped, and I’m about to apply the thinset. I’m keep the current drywall ceiling. Do I need to tape and thinset the seam between the top of the cement board and the drywall ceiling? Or do you think it’s fine leaving it as it and tiling up to the ceiling? Thanks!
Tom Latcheron says
I plan installing a U-shaped 3z7x8 ft shower within three 15ft * high walls, two of which are open stud walls covered with drywall and one narrow wall is plywood. I contemplate replacing the dry wall on the stud walls in the shower area with Denshild flush with the surrounding drywall and then mount all shower walls with Kerdi board which would give the same tile reveal on all walls but with an unsightly 1/2 inch reveal or alternatively mount the Kerdi board directly to the studs and plywood and deal with a differential 1/2 inch tile reveal only on the plywood wall. How is the best way to handle this wall variation.
You don’t need to tape it but you could if you wanted. If you did, it’s important to tape the tile side with thinset and the drywall side with drywall compound.
What you could do is install 1/8 inch Kerdi board over the plywood and install 5/8 inch Denshield over everywhere else.
Hi Jessie –
I’m currently going through a reconstruction of my shower and master bath after the first contractor failed to properly waterproof the shower (liquid waterproofing over cement board that was not applied thick enough or protected at the seams) and according to California building code you cannot use green board in a shower surround or anywhere it will be in a high moisture environment: “Water resistant gypsum board/green board/purple board shall NOT be used in the following locations:
• In Showers were it is used as the tile base or backer.
• Where they will be direct exposure to water or in areas subject to continuous high humidity
• On ceilings where the where the frame spacing exceeds 12” on center for 1/2” wall board and more than 16” on center for 5/8” water-resistant drywall
It’s on page 7 of the California building inspection checklist and guildlines for “Bathroom Inspection” and if done will not pass an inspection for a permitted shower in the state.
Thank you for this information! Very helpful.
Hi,I’m in the process for tiling my bathtub.
I’m going to use densheild tile backer board.
I have few things to ask,manufacturer said no need to use waterproof membrane on densheilds even on top if the screws.
1. Would it be ok only to use 100% waterproof silicone caulk between the seams and the corners?(Could also use a mesh tape and add silicone on top of it if this will be better)
2.Can I use 12″x24″ porsaline tiles on the densheild? It will be 5 tiles hight.
3. What kind of thin set /adhesive to use for these tiles.
Hope to get a reply..thank you
Denshield simply says to use “flexible sealant/caulk” on the seams but I don’t see where they specify anything more specific than that. So, silicone should be OK but you have to be very careful not to get the silicone on the surface as nothing sticks to silicone.
12×24’s will work just fine and you can use any kind of modified LFT mortar to adhere them.
Mindy Allan says
I recently had my bathroom renovated. The contractor used penny tile on the floor of the shower (as well as all the flooring in the bathroom). After everything was done and I showered I noticed there was a pool of water in the center of the shower. The drain is to one end. And the drain does not appear to be clogged. When I asked my contractor about this he said the water was not flowing smooth/quickly to the drain was because of the penny tile and it was normal. I have done a lot of research and nowhere can I find anything that says water should not drain quickly from a penny tile floor. The contractor said he used the same slope that had been there before. Is it possible to fix this? Thanks.
Your contractor is full of it. The water should drain and not sit inside the shower. What’s you have in your shower we call a bird bath and they aren’t acceptable. He’s going to have to fix it.
john calvey says
Hello my question is ,would it be beneficial to use both 3 mil plastic behind the Hardie board and then also roll on
2 coats Aquadefensee over the Hardie board after taping the seams
No. I know it seems like it would be better but it has the possibility of trapping moisture in between the two layers. You’re better off sticking with one over another. Typically, the liquid is the better choice.
I’m building my first shower in our new master bedroom/bathroom addition. Not thinking ahead, I purple rocked the walls in the 5’x8′ walk in shower. I’ve already installed the sand mix pre slope and installed the 40 mil oatey liner on top of that, extending 6″ up the walls all the way around. I began installing the durock, and that’s where my brain started thinking about possible moisture going through the cement board and getting to the purple board. I have plenty of the 40 mil leftover. Should I remove the few pieces of durock and go ahead and extend 40 mil up the walls to shower head level, letting it overlap at the bottom a few inches? Then continue the durock. Will this trap moisture or serve as a vapor/moisture barrier?
Put the liner on top of Durock all the way up. You could “paint”
the Blue board with the membrane in the bucket stuff to provide
Some moisture protection for the blue board which provides
Additional rigidity for durock. I used the bucket stuff also on
The underlying studs.
I don’t understand why you would have purple drywall and then Durock over the drywall? Is there any reason the drywall can’t be removed and then the Durock over the studs?
Yvette T says
My shower is currently being re-tiled, and several red flags appeared which lead me to investigate deeper and get multiple opinions from other shower installers. Aside from very crooked tiles, the contractor used this dark green-looking paint directly over the cement board in the shower pan and ledge before laying the floor tiles. He admits to “testing for leaks by pouring buckets of water and watching it drain properly,” which leads me to believe he did not actually fill the pan with water and let it sit as recommended. When confronted, he says a shower pan liner was used as well as a water proof membrane. How can I verify this, since tile has already been placed in the pan?
It sounds like it’s not being built by-the-book. The green waterproofing is a good idea and should cover the entire shower unless he put a moisture barrier, like plastic sheeting, behind the cement board.
Additionally, the curb should not have cement board nailed on it with waterproofing over it if he used a liner in the shower pan.
Unfortunately, a lot of showers are built this way and there is no industry standard or recognized method for this type of construction. See if your installer can come up with some sort of documentation to back up their method. They won’t be able to find one.
All of that being said, failure is not a guarantee but the chances increase in likelihood with each wrong step.
Brent Robinson says
I just finished installing tile in a bathroom wall over the top of hardie board that had been waterproofed with red guard using Mapei Type 1. After finishing I noticed that Mapei recommends that their product not be used over waterproof membranes. Any suggestions? Do I need to rip it out and start over?
If you haven’t grouted yet then I’d be inclined to remove the tiles and redo it. On the bright side, removing and scraping off the adhesive should go rather easily.
Then, just keep track of the order they go in and reinstall. It should go quicker the second time because all of the cuts are already made.
First of all. What a fantastic website for tiling information. Thank you, you have already made my life easier.
I am renovating a bathroom and installing a custom tile shower with kerdi and cement board backing. I have a question about where to place the cement board to drywall joint on the walls. I feel like there’s three criteria to take into consideration but want to make sure I’m not missing anything obvious.
1) Where the studs are – both cement board and drywall require solid backing at the joint.
2) Have cement board behind the wet area.
3) Have the joint a few inches to the shower side of the tile edge so you have room to mud a smooth transition on the drywall from the mesh tape.
Sounds about right? In my case the cement board to drywall joint looks to be about where the shower glass will be. I was initially concerned, but the kerdi will extend an inch or two beyond this…so should be okay?
I am positive I am overthinking this (as always) but it’s my first shower.
You’ve got it and thought it out perfectly! It’s OK to have the joint behind the glass and, as you mentioned, the Kerdi membrane will extend past a little bit to make sure the waterproofing extends past the area that will be exposed to water.
Two more if you don’t mind.
1) I usually use 5/8″ drywall on exterior walls (one of the shower walls is exterior). I’m assuming it’s not worth the hassle of mudding the transition down to 1/2″ cement board and I should just use 1/2″ drywall in this case?
2) Do you recommend tapping the joint between the wall cement board and the ceiling drywall? My tile will go to the ceiling and the ceiling above the shower will be drywall. If so I assume to use mesh tape and smooth out the ceiling side with drywall mud afterwards? Just want to make sure there’s no advantage to letting that joint be free.
Questions about using corian in a shower?
I was wondering if I could use 1/2 inch corian as a solid surface for the shower bench, curb and shelf for the niche? I am having concerns about how to adhere it to the waterproof membrane that I just installed over permabond cement board. I have read that you should use silicone to attach corian to walls but don’t think that will adhere to the fabric. Some people have recommended Kerdi-fix but worried about the curing and rigidity. Also possibly Flexbond, but am concerned about using a modified thin set over the waterproof membrane because of the curing time needed (28 days?). Everyone says I need to use unmodified thin set to set my porcelain tile to the membrane, which I used to between the membrane and cement board. I guess I am thinking I might not be able to use it because I read that corian expands and contracts and if too restricted with too much adhesive or non-flexible adhesive it can break. Anyway, looking for some expert advice on whether to proceed or just stick to the tile instead.
1. You can buy drywall shims and staple them to the studs so they make the drywall even with the backer board. They are also nice to flatten walls prior to installing the backer board.
2. If you can tape it without too much trouble then that’s the way that it should be done.
You can use Corian if you like. I’d probably lean towards Kerdi-fix for adhering it but the other products might work too.
I know you’re suppost to leave a 1/8″ gap in between cement board sheets, but what about in between the cement board and drywall (both on the wall and at the ceiling corner)?
You definitely need the gap if you are going to fill it with sealant. Otherwise, it’s probably not absolutely necessary. However, gaps aren’t a bad thing.
When you say fill the gaps with sealant, are you referring to a RedGuard type product? Just making sure I’m not missing a step between taping the joints and putting on the kerdi.
The is nothing wrong in any way with green board with red guard in showers
The substrate matters not , all need to be sealed .
Perhaps your not familiar , and or have been involved with bad jobs .
Ive got showers that have been installed with green board for over 30 years with no problems .
A house I sold in 1990 I did green board , the owners wanted to enlarge/ up date the master , I tore out the entire room. As I expected zero damage .
I’ve always used green board , I’ve used other systems as well as hardy , dura rock , though I use dura rock on floors , To me there is no reason , no advantage to the extra cost which is better spent on fixtures etc and of course the extra work and mess .
Nowhere on the Redgard instructions will you find green board, or any drywall, as a suitable substrate. You are welcome to build showers however you wish but that doesn’t change the fact that drywall has no business in a wet area. It’s ridiculous to recommend installing it in a shower and it’s against building code.
1. Is it necessary to use felt or tar paper behind GoBoard in a shower and bath tub surround?
Or should the boards just be painted with RedGard or HydraFlex.
2. I am building a new shower. I noticed two things the contractor has done; 1) Laid Durock on the shower floor before making the shower pan. 2) Left a section of the old plaster dry wall with chicken wire on one of the shower walls (use to be a closet). From everything I’ve read this seems incorrect. Is it?
It’s not necessary, and probaby not advisable in most situations, to have tar paper behind GoBoard. Additionally, Redgard should only be painted on the seams if they are filled with mortar and mesh tape. If they are filled with sealant, additionally waterproofing shouldn’t be used on the seams.
The Durock on the shower floor is completely unnecessary but won’t hurt anything if installed correctly. The old plaster wall seams like it should be removed.
Dave Lee says
I have a standard fiberglass shower/tub with fiberglass walls. There is about a 12 inch gap between top of fiberglass surround and the the ceiling. That space was filled with blue board drywall and doesn’t get direct spray from showerhead. Could I apply a subway tile between the top of the shower surround and ceiling to the three walls encompassing the shower/tub area? what would be the protocol of doing this? Thanks for your help.
Yes. For something like that, it is considered out of the wet area and you can install the subway tile directly over the drywall.
John Thompson says
Related question. I’m putting in a 3′ corner shower with a glass enclosure in a small bathroom, there’s currently cement board forming the walls of the shower and drywall directly next to it, out of the wet area.
Because the space is so small we realized it would look really great to tile the shower and the 3′ of drywall next to it one of the shower walls the same tile. Seems like the danger would be moisture from the shower migrating through the grout into the drywall. Would it be reasonable to mediate that by putting a moisture barrier (either redguard or kerdi membrane) over both the cement board and then tiling the whole area?
You should have a moisture barrier, like Redgard or Kerdi, over the wet side of the shower enclosure. It’s not necessary to have the moisture barrier outside of the shower.
It is possible for moisture to travel through the grout joints and escape outside the shower but it’s not very likely. Especially, higher up on the wall. With that being said, there is nothing wrong with installing cement board on the wall outside the shower that is intended to be tiled over.
Kevin Oran says
I wonder if you had any preference between Mapei’s Keracaulk S, Keracaulk U, or Mapesil T?
I need to use caulking for both bathroom tile as well as for a movement joint on a tiled basement floor. It’s not clear what the differences are beyond that Mapesil is rated for high traffic areas.
My grout lines are 1/8″ inch.
Thank you in advance,
You definitely want Mapesil T. The other two are water-based and don’t perform. Mapesil is more difficult to use. Make sure that you read this post and watch the video tutorial for how to apply silicone caulk.