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6 Things NOT To Do When Building a Tile Shower


6 Bad Remodeling Ideas for Tile Shower Construction

Sheetrock in a shower and other bad ideas

drywall shower sheetrock
This is how you waste money on a shower

Sometimes it’s nice to know what-not-to-do when remodeling a tile shower in your bathroom. Here’s a list of just a few of those things:


1. Drywall Shower Walls

Drywall (sheetrock) falls apart when it gets wet. Putting a product like this in a shower is just a bad idea.

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” for showers.

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.

Shower Waterproofing Crash Course

Tile Backer Board Breakdown

2. Not taping or 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.

Mesh Tape: Don’t skip this step

Make sure the seams in your shower enclosure are covered with alkaline resistant mesh tape.*

waterproofing fail in shower
Waterproofing is necessary on this half wall and should be flashed up on the wall where it ties in

3. No waterproofing

I’ve covered this elsewhere but a shower should be waterproofed. So if you see a contractor tiling directly to cement board or Hardibacker then check and see if there’s plastic or tar paper behind the wall.

If not read these posts and have a talk with him or her.


No Waterproofing: Will this cause shower leaks?

Is Hardibacker and Durock cement board waterproof?

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.

“Drywall is highly vulnerable to moisture…” Wikipedia

5. Mastic

There are very few situations that mastic is an OK choice. Don’t use tile mastic in wet areas, over cement board, fiber cement board, Kerdi, floors, or with glass tile, large format porcelain tile, natural stone, or most anywhere else. The only place it’s OK to use it is when tiling in non-wet areas, over drywall, with small ceramic tile. These days that’s almost nowhere.

Avoid These 3 DIY Tile Installation Products

shower flood test
Shower flood test in progress

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. Consequently, I would write it into your contract with your tile contractor.

A simple flood test will help to determine this. I would write it into your contract with your tile contractor.


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:

5 signs your new tile shower will leak

*Disregard if you are using a waterproof sheet membrane system. Always read the manufacturer’s instructions.



  1. HI-
    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.

  2. Hi,

    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.

      Good question!

  3. 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.

  4. 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.

    • Tim
      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?

  5. 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.

  6. 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

  7. 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.

  8. 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???

  9. 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 .

  10. concerned remodeler

    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.

  11. 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

  12. 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

  13. 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.

  14. 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?

  15. 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.

  16. 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.

      • 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?

        • 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.

  17. 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

  18. 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.

      Good luck!

  19. 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?

    • 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.

  20. 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?

    Thank you!

  21. 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.

  22. 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.

  23. Hi
    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.

  24. 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.

  25. 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.

  26. Green board and drywall is all molded (black). This stuff is coming out today. What goes back up to waterproof the bathroom?

  27. 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?

  28. 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.

  29. 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?

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