Just look at you! Sitting there with a hole in the wall of your shower. What are we gonna do with you? If you do not happen to be sitting there with a hole in the shower of your wall read How to Build a Niche for your Shower – Part 1 and join all the cool kids. We’ll wait…

There, now you’re one of the cool kids. Now take your beer Pepsi off that niche shelf so we can waterproof it. You have a couple of different methods with which you can accomplish this.

Liquid Waterproofing Membranes

These products are usually readily available and fairly simple to use. Products such as Custom’s Redgard and Laticrete’s 9235, Hydroban, Hydrobarrier, etc. are all a thick, paint-like product which is brushed or rolled on to your substrate to waterproof it. You should only use these products if you are using a cementious backerboard as your shower substrate, they should not be used over regular drywall.

If you do have a cementious backerboard and choose to use one of these products for waterproofing simply follow the directions with whichever product you choose. Make absolutely certain that you get enough of the product in your niche to effectively waterproof it. The specifications vary but the best way I can explain it with a general rule would be the thickness of a credit card. Two or three good coats and you should have a layer on your substrate equivalent to the thickness of a credit card – that would be the correct amount.

I use to waterproof niches this way until I started doing them with Kerdi. Unfortunately I don’t have any photos of a niche I’ve waterproofed with a liquid membrane. Just make certain you have every (literally) pinhole and corner covered very well. For the remainder of this post I will describe waterproofing your niche with…

Schluter Kerdi

Kerdi is now my preferred method of waterproofing a niche, bench, floor, wall, beer Pepsi cooler, just about everything. For those unfamiliar with Kerdi it is the orange membrane on the shower walls in all my photos.  It is a thin polyethylene sheet which is installed directly to drywall and/or deck mud as well as other substrates, to make it waterproof. It is easily cut with scissors or a razor blade and can be folded, molded around curves, etc. and is installed directly to your substrate with regular (unmodified) thinset. A very versatile product.

While there are countless ways to utilize Kerdi to make your niche waterproof I am going to walk you through the way to cut and install it using one single sheet cut to size for your niche. I say type there are countless ways because there is really no *particular* way which Kerdi must be installed. As long as every piece is overlapped 2″ your substrate will be waterproof – no matter how many pieces you use. I just prefer a single piece cut to whatever size I need for the particular niche.

Measurement diagram for Kerdi nicheSo what size do you need for your niche? Here’s how to figure it out. The badly created diagram to the right explains it better than I can with words, you can click on it for a full-size version.

It is basically the width of your niche plus the depth (twice)  plus 2″ (twice). See? I told you the diagram was easier.

For my 13 x 13 x 3 niche the measurement for the piece of Kerdi is 23 x 23. That is 13 + 3 + 3 + 2 + 2 = 23. Width + depth + depth + 2 + 2 = width of kerdi. The two inches (twice) is for the overlap on the outside of the niche. Remember I said kerdi needs to be overlapped 2″ – that’s what that is. 2″ on each side of the niche.

For a square niche both measurements will be the same. If you are creating a rectangular niche the width and height measurements will be different – they need to be figured differently.

Kerdi marked for shower niche

Photo 1

So here is my piece of kerdi for the niche. (Photo 1) You can see the measurements marked out. Take a ball-point pen or pencil and mark the measurement lines on the piece of kerdi.

At the bottom right of this piece I have marked the two partial cuts you need to make in every corner as well as the small square piece to remove. (Hold on to that piece – don’t throw it away)

Cutting each corner in this manner will allow you to fold the kerdi into your niche correctly and have an exact fit. Make sure you do not cut the lines too far, it’s always better to cut them a bit short and fine-tune it later.

Kerdi cut for niche

Photo 2 - Kerdi cut for niche

In photo 2 the kerdi is cut to fit into the niche. After you get it all cut you should place it into your niche to ensure that it fits correctly. Just take the piece of kerdi and place it into your niche like photo 3 here:

Dry-fitting the kerdi

Photo 3 - Dry-fitting the kerdi

Take the inside corners – the ones that go into the back corners of your niche, and push them tightly into each corner. If measured correctly the corner marks on the inside square should fit perfectly. Wrap the top and bottom flaps over the niche and onto the wall outside.

The side flaps then get smoothed onto the sides and all the strange corner pieces you cut out will fold over the top and bottom flaps and outside to the wall with a 2″ overlap. If fitted properly it should look like photo 4 here:

Correctly cut and fitted kerdi for niche

Photo 4 - Correctly cut and fitted

At this point make any minor adjustments in the cuts or remove any excess you may have and make all the folds over all the corners to make sure they fit tightly.

After you ensure that the fit is correct its time to actually install it. Make sure you are comfortable with the way it fits and how it folds into there. Remove it and replace it a couple of times until you are sure you know how to do it. Once you start playing with the thinset it gets really messy very quickly if you need to make adjustments. I became a tile guy because I like playing in the mud – you may not.

Pull the piece out of there and comb your thinset into every corner and part of the niche and about 2 1/2″ around the outside of the opening. You need to make sure you get every little bit covered. There must be full coverage behind the kerdi to make everything waterproof.

Combing thinset into and around niche for kerdi

Photo 5 - Combing thinset into and around niche for kerdi

Placing the kerdi into the niche

Photo 6 - Placing the kerdi into the niche

When you go to place the kerdi into the niche you should fold in the sides as it will be placed into the wall. By folding the flaps over and in before placing the kerdi in it will help get it in the right place with a minimum of mess.

Start with the upper two corners in the back of the niche and press them in there very firmly. Make sure the line between those two corners follows the corner of the wall in the upper back of the niche. This is why you want to draw all the lines onto the kerdi – it will assist in getting the piece all lines up and in the space straight and square.

When you get those corners and the line between them pressed in firmly run your fingers down each side of the back of the niche to make sure the lines follow the niche. The lines you drew on your kerdi should follow the lines of the niche exactly.

Smooth out the entire interior of your niche starting with the center of the back wall and working outward. You need to make certain there are no air pockets behind your kerdi. Once the back wall is firmly in place start with the sides of the niche working from the back to the front wall again ensuring no air pockets remain.

Once the entire inside of the niche is smoothed down and flat start with the main flaps by using your index finger and thumb along the outside edge of the niche to get a nice, square transition around the corner like this:

Smoothing outside edges of niche

Photo 7 - Smoothing outside edges of niche

If you look closely (or click on it for a full-size view) you will notice that only the first inch or so around the outside edges are completely smoothed down. You want to get that nice and tight before worrying about the remainder of those flaps.

After you get the large, main flaps installed and smoothed out flat you can start with the inside corner flaps. Just do one or two at a time and don’t rush through these – they are the point where your overlaps create the waterproof aspects. I do the two opposite corners at a time.

Installing two of the corner flaps

Photo 8 - Installing two of the corner flaps

Finish installing the remaining flaps

Photo 9 - Finish installing the remaining flaps

You want to take considerable time and great attention to detail while installing these flaps. The tighter the seams are together where they overlap the more dependable they will be. Kerdi is made waterproof by the overlapping and attaching of the seams – the tighter the better. Get it all smoothed out and tucked in and you will have an absolutely waterproofed hole in your shower wall. That is, after all, what you are building – a hole in the wall.

Now, if you are anal retentive attentive to detail like I am there will probably be one or two spots which may concern you for one reason or another. Remember those 2″ square pieces you cut out of the corners that I told you not to throw away? There’s your patch. Just comb thinset over the spot that’ll keep you awake tonight and install the patch over it. The outside corners of your niche may be one of those areas.

See photo 9? It’s a frickin’ mess. If you aren’t making a bit of a mess you aren’t doing it correctly. Yours should be a bigger mess than mine. Don’t be afraid of it – thinset is your friend. Besides it looks better after is sets – see:

Finished waterproof shower niche


If you do it the right way you will never have to worry about leaks, standing water or any other fun problems associated with an improperly built hole in the wall. When done correctly you will end up with an absolutely waterproof niche in which to store your rubber ducky! See:

Niche for your rubber ducky

Thought I was joking, huh?

You thought I was joking about the rubber ducky, didn’t you? I wasn’t. I build showers – I like rubber duckies.

In my next post I will describe various ways you can place tile in your waterproofed niche for maximum rubber ducky storage.

{ 236 comments… add one }

Leave a Comment

  • vic

    do all tiles come with a standard bullnose and what size (depth) do they usually come in

    • Roger

      Hi Vic,

      No, not all. It depends on the manufacturer. Standard bullnose is normally the length of your tile and 2 3/4″ – 3″ wide.

  • Tara

    I am about to start tiling my tub surround and ceiling above. I might have gotten in over my head but we shall see. I want to make a rectangle niche that stretch’s the length of the back wall. Is this possible. It would mean cutting the studs.
    Thanks for any advice.


    • Debbie

      Hi Tara,
      A few questions…
      First, is this on an inside wall or an outside wall (and is it load-bearing?)
      Second, how wide of a horizontal niche are you looking to make?
      Third, is permitting required in your area if you are altering a structural component of your home?

      We designed three niches in our shower – but were not nearly as adventurous as you…we stayed within the studs. However, if you want to proceed with your plan, it makes sense that you would need to prepare your niche framing much like you would for making a frame to install a window. Again, look above re: load bearing question. The studs still have to be able to perform their structural duties…so reinforcements between the studs with a header, double sill plate and extra side supports. Nail everything together well. As this could be structural, it is critical that it’s done right…if in doubt, get professional help for this. Good luck!

    • Tara

      Thanks Debbie,
      It is an outside wall and I am sure it is load bearing. I thought that we could frame it out with 2x4s but I’m not real sure about that. I really like the look of a tub length niche but it might not be possible. No idea if a permit is necessary but I would look into it if I thought I could do it. What do you think?

      • Debbie

        Yes, an outside wall is load-bearing. If you are wanting a wall-width niche -you are looking at 5 to 6 feet across, right? That means several studs being cut. Which floor is this bathroom on and how many stories tall is the house? It’s not that it can’t be done, but it will be some work. Take a look at YouTube on how to safely do remodel work involving a load-bearing wall. Do you have access to professional help (reputable contractor or engineer) to take a closer look at this? An alternative is adjoining niches that run the back length of your tub…between the studs.

    • Roger

      Hi Tara,

      It is possible, but it will require cutting the studs to accomplish it. If that is a load-bearing wall you can not mess with the studs.

      • Rich

        Tara, first just because it’s an outside wall does not make it load bearing. For instance if it’s on a wall that has a gable end in the roof it may not be load bearing. To know for sure you’d have to know if the ceiling/floor joists ran with or perpendicular to the wall. If they run with the wall it’s most likely not load bearing. Either way it can still be done but you would have to brace the ceiling/floor above temporarily and install a header above the niche. If you have any doubts ask a knowledgeable carpenter.

  • CliffStoll

    For a shower, we’re putting up Densshield on the walls, with a schluter presloped foam pan.

    We will put kerdi over the foam pan. Should I continue the kerdi up the Denshield walls?

    Is it OK if I do, or is this a no-no?


    • Roger

      Hey Cliff,

      Yes, that is the proper way to do it.

      • CliffStoll

        Super! Many thanks… Quick further question:

        Above the Kerdi plastic curb will be a place for a shower curtain: a 7 foot tall, 4 inch wide “passageway”, extending about 8 inches on each side. This will separate the shower from the bathroom.

        No door, just a place for a shower curtain to hide behind. There will be 28 inches between the two stub-walls.

        I will frame this with 2×4’s, cover on both sides with densshield, and then kerdi overall.

        How should the base of this “curtain shield” connect at the bottom:
        – 1) by going all the way to the floor with the wood. This means the plastic Kerdi curb will be short – about 28 inches – inbetween the two stubby walls.

        – 2) by bringing the 2×4 curtain shield wall down to the top of the Kerdi curb? So the curb will extend below the 2×4/denshield/kerdi stub-wall, and the curb will be 44 inches long. In this case, how do I connect the bottom of the stub-wall to the curb?

        – 3) Alternatively, I could make the stub-walls from Kerdi Curb. If I did this, how would I connect the plastic curb to a wall?

        Many thanks from Oakland, California!

        • Roger

          Ummm, I’m gonna need a picture of that. I have no idea in hell what you have going on there. :D

          Not necessarily a bad thing, I just can’t visualize what you’re doing. You can upload one here: Photo upload

          • CliffStoll

            No prob – I think these may be called curtain pockets. I’ll upload a drawing. Tnx

          • CliffStoll

            I just tried uploading 3 photos, but i do not know if any got there.

            If the 3 diagrams loaded, then the brown area represents a 2×4 construction covered with densshield & kerdi. The pink repesents Kerdi curbing.


            • Roger

              Build the curb all the way across then build the walls to be waterproofed, tied into the curb, on top of it.

              • CliffStoll

                Sounds good – Any suggestion on tieing the short 2×4 wall to Kerdi curbing? Construction adhesive?


                • Roger

                  Kerdi-fix. Construction adhesive will dry out and give up over time. In reality it doesn’t matter which order you do it (curb with wall on top, wall with curb butted to it, etc.) as long as you have everything covered with kerdi and the proper overlap it’ll be just fine.

                  • CliffStoll

                    Very deep thanks – I bow to your expertise.

                    With a tip of my head to the judges, I will now cheerfully dive into an ocean of unmodified thinset…

  • John Anthony


    Love the site and I’m glad I found it when I did. I was about to use the really cheap thinset from HD, 1/8 spacers, and bad sealer. I am using the kerdi system with the preformed shower pan. I will definitely be using your niche techniques. I read above that you dont have an issue with the tiny tiny pinhole that could be in the corner of the niches in kerdi since you are overlapping, so if you dont have a problem then I will ignore that. I will be using a tumbled travertine subway tile that is filled on the face. Any advice for travertine that I should consider. (I’m using it so don’t talk me out now lol). I have some corners of a tub to go around and not quite sure how to do the edges. I do have grinding equipment and diamond pads all the way up to 3000 grit. (I’m going to do the top of the curb and bench in a granite tile and need to make my own bullnose). I was told by the HD guy I should seal before I put the tile on the wall, but I really don’t trust those guys. I have also read with unmodified thinset, kerdi and travertine that I should let this cure for 2-3 weeks before grouting. I’m sure I will have more questions along the way. This is my 4th tile job and I have learned the mistakes along the way, fortunately they turned out very good. I will have to send the pictures of the butchered job the builders did when they built this place at some point. You will cringe. I’m afraid to find out what is underneath. But thank god I have another bathroom to use for a while. And Jack and Coke.

    • Roger

      Hi John,

      You can just polish the edges of the travertine just like you’re doing with the granite. Do not seal it before you install it. You can seal it before you grout if you want, makes it easier to clean up as you grout. Any unmodified thinset will be initially cured after 24 hours. You DO NOT need to wait 2-3 weeks, that’s assinine. I’d never get anything done, I could do like ten jobs a year at that rate. :D Grout it the next day.

  • LaNell

    OK… Correct me if I am still confused on this. Please do NOT let my little dog go up in flames. There is KERDI BOARD that is put up over practically anything. Then there is Kerdi/Schluter MEMBRANE. The latter being like wall covering of sorts over Durock.
    Anyway, I am not brave enough to trust the pan to anything but a Tileready or whatever that other one is (KRBS?? ). As to make myself feel better about my tile work not falling off walls, what about RedGard with KERDI membrane corners? Silicone in wall and floor corners? Membrane on every seam AND RedGard?
    Don’t mind the expense so much as the worry of a flaming Chihuahua. Meaning I want my 30″x54″ waterproof.

    • Roger

      That’s fine, you can just install the corner membranes directly into the redgard, then paint over it with more redgard.

  • Donna

    We built a niche in the shower we are renovating. Before finding your most wonderful and helpful website, we covered all the wall studs with roofing felt, then cement backerboard. Reading here, we learned that liquid or kerdi membrane is the best way to waterproof a niche. All we could find at our home improvement stores in the way of these items was kerdi band and didn’t want to pay lots of $$$ for the liquid redguard type when we had already used the roofing felt underneath. Soooo, what is the best way to proceed now for our niche only? Should we remove the roofing felt and use the kerdi band? We were thinking we could use the mesh tape and thinset for all gaps and joints, and possibly add the kerdi band in addition for every seam and joint in the niche. What do you think? Thank you!

    • Roger

      Hi Donna,

      The redgard is your best bet. The entire face of all the backer in the niche needs to be covered – backerboard is not waterproof. If you are just doing the niche you can leave the roofing felt.

  • mindi friedman

    We are redoing a bathroom and putting in a new shower where a tub used to be. My framer is using Denshield on the shower walls and the plumber is using the proslope system and waterproof membrane for the shower pan. Then the tiler is going to “float the mud” on the shower floor and do the tiling. I would like to install a niche between the studs. If we are using Denshield all around and in the back portion of the niche, do we still need to line it with a waterproof membrane?

    • Roger

      Hi Mindi,

      You don’t need a membrane in there, although it never hurts, but you do need to ensure you get everything sealed up really well with the seams and penetrations of the denssshield in the niche.

  • Leni

    Hi Roger,

    I was reading another blog of yours about the proper way of doing a tile shower and I believe there you mentioned doing Kerdi and then covering with RedGuard as well… Is that a vital (or recommended) step or can it be skipped using just Kerdi on the drywall before tiling? Also, what would you suggest for the subfloor before doing a tile floor? Thank you!


    • Roger

      Hi Leni,

      I don’t know where you would have read that on my site. I sometimes seal kerdi-board seams with hydroban, but have never put redgard over kerdi, unless it was to seal the seams when not using kerdi-band. You can just use kerdi, or just use redgard, or use both should you choose. Any of them work.

  • Eugene Caldwell

    I like the KERDI fix instead of HydroBan. That way I am not mixing two manufacturers. You know how fussy they can be when you have to file a claim for a failure. hahaha. ( just kidding. ) but, honestly, the fix is a very good product. You just have to use it after the thinset dries. Good job.!

    • Roger

      Hi Eugene,

      I have no idea to what you may be referring. There is nothing at all on this page where I refer to using hydroban with kerdi. Kerdi-fix is not a waterproofing membrane of any sort (which is where I mention hydroban), it is a sealant used with kerdi and kerdi-board. I’m sure you know this, but someone reading this without context, as it was posted, may be confused more than they may already be while searching for an answer. Kerdi-fix is a very good product.

  • Shawn

    Hi Roger –

    Love the guide and the website – thanks for posting all of this helpful information! I have a question about the outside corners of the niche – it doesn’t look like there is any Kerdi liner being used where the little corners were cut out of – just thinset. Am I seeing this correctly?

    Thanks again!

    • Roger

      Hi Shawn,

      In that particular shower no, there is nothing there but thinset. I left it a bit long an kind of ‘curled’ the outer corner out so it overlapped the kerdi on the wall. A better option is to take the little corners you cut out of the niche piece and install them at the four outer corners before installing the niche piece. I will also use hydroban at the corner seams, which I tend to do a lot now, but it’s really not necessary.

  • Phil

    Thank you so much!!! It really helps.

  • Tom

    In the sample picture above, the one with your rubber duckie, I like the way you wrapped the glass mosaic listello into the niche. How did you handle the exposed ends? Did you make cuts and sand down the sharp edges (if so with what)? Did you individually remove some of the glass pieces from the mesh and line them up to interlock like a puzzle? Or, did you use another of your crafty tile guy methods?

    • Roger

      Hi Tom,

      I use uncut sides on the exposed ends and interlocked them. You can also bullnose them and polish them – if you have the $1200 worth of polishing equipment. :D

  • Jason

    Can I ask a really stupid question? You put 4 screws through the Kerdi for the braces for the shower niche. The manufacturer says not to puncture the Kerdi in any way. Is it water proofed with the Kerdi that sits in the niche? I am about to start my walls and want to use this method. I have done tile before but never a shower. Your site is absolutely awesome. Thanks

    • Roger

      Hi Jason,

      The manufacturer says a lot of things. :D It is fine to puncture the membrane as long as you cover it with kerdi and have a 2″ overlap. The screws are 3/4″ below the niche, the membrane in the niche runs out and down the wall 2″, so they’re covered and waterproof.

  • Nick

    I’ve used your site & help a ton and it’s always been greatly appreciated, but I must say this post on cutting the Kerdi for the niche is top notch my friend. You honestly saved me hours and lost of wasted brain power trying to figure out the best way to do this. Followed your instructions step by step and it was a breeze !!!!

    Have a great day ELF !!

  • Will

    Hey Roger, great site you have here. I had a question about waterproofing with Redgard. I decided to use Redgard with cement board, so what do I do about the gap between the tub lip and the cement board as far as the Redgard is concerned? Do I just Redgard everything cement board-wise, then just tile over that, leaving the gap for the thinset?

    Thanks very much

    • Roger

      Hey Will,

      Silicone that gap so you have a continuous waterproofing layer from the wall down into the tub. The redgard won’t really cover the silicone well, but it doesn’t need to, you’re just ensuring that any tiny missed areas are waterproofed.

      • Will

        My cement board is mounted 1/4″ above the edge of the lip on the studs, so do I just silicone that 1/4″ gap, or the whole gap between the tub and the wonderboard, which is about 1″? Thanks again Roger, I really appreciate everything you do on the site for everyone.

        • Roger

          If it’s that large you should put some backer rod in there first to fill it before the silicone. Backer rod is a little cylindrical foam rod you can find at any big box or hardware store.

  • Stephanie

    When bullnose tile is not available, is there a schulter profile you would suggest for the shower niche? Not sure of the difference between say the jolly, rondec, etc for the niche specifically or if something else works better. Thanks!

    • Roger

      Hi Stephanie,

      Rondec is your best option, although any of them will work. Most people choose the jolly profile, they’re normally less expensive.

  • Jim Dare

    Roger, I’ve studied hard, marked carefully, and today was the day for me to screw up my courage and cut into my beautifully redgarded waterproof wall. The cuts came out fine – but I’ve run into two problems.

    Problem 1: We had a local contractor install the backer board. At some point after I had taken photos of the stud locations, he added one I didn’t know about. When I cut my niche out, the right side cut is exactly flush with the stud. Can I simply run the right-side piece of inside backer board out to be flush with the outside of wall? I’ll be waterproofing with redgard, so I think I need to tape and mud the joints anyway (right?). Is there any reason I can’t run tape up the face of that right-side piece and mud it? I’m sort of assuming simply redgarding the stud and tiling to it is asking for trouble.

    Problem 2: The backer board where I cut the niche is 1/2″. Sadly, all the backer board we have left over is 3/8″. My finely-honed math skills tell me this is going to leave me with a 1/8″ gap at the back of my bullnose tiles inside the niche. No good. If I have to go buy a whole freakin’ sheet of 1/2″ backer board to Do the Niche Right, I will. But is there a good way to shim between a 3/8″ piece of backer board in the back and the original 1/2″ piece I cut out?

    • Jim Dare

      For Problem 2, maybe I could use a bunch of my 1/8″ tile spacers and glue them to the front of the 3/8″ backer board. Then when I slide my 1/2″ piece in there, it should come out right. Whaddya think, Roger?

      Thanks again for all your help.

      – Jim

      • Roger

        That will work as well.

    • Roger

      Hey Jim,

      1. Yes, that will work fine. Yes, you need to tape and mud seams and yes, redgarding bare studs is trouble.

      2. You can place big globs of thinset on the back of the 3/8″ piece and only push it in there as far as you need it. Let it cure and it should be right where you need it. You can also do that with the tile in the back of the niche, it doesn’t necessarily need full coverage, you can glob the thinset on there and only push it back as far as you need it. (provided you aren’t using mosaics, that is)

  • Travis


    I read (and even found helpful)….sorry, snarky is required right?…your manual on using Kerdi. What I’m not grasping yet is putting Kerdi on a triangular bench…the inside and outside preformed corners don’t seem to me to work for the “odd” angles. Help!


    • Roger

      Hey Travis,

      You can’t use the pre-formed corners there. You just need to cut from the outside of your sheet down to the very corner, fold down one side and get it bonded, then fold the other side over that and get it bonded. I normally cut a little square or circular patch to place over the very corner of the fold, where you cut it down to.

      You CAN use the pre-formed outside corners, but you’ll need to cut the fold where it normally lies over the square curb. Cut along that line to the halfway point. They’ll split out from one another when you install it, but you can then just place a patch over the open split.

      Did you understand all that? It’s difficult to explain specifics of kerdi with just words sometimes.

  • Greg

    Hey J

    I see I am to use un-modified thin-set with the Kerdi membrane. At my local box store they sold me a thin -set that is polymer modified and told me this is to be used with all schluter products Kerdi and Ditra. Can this be used?

    • Roger

      Hi Greg,

      It can be, but it shouldn’t be – you’ll lose your warranty. If you read my unmodified thinset information it’ll give you the different options available. Stop listening to the guys at the big box store, most of them have no idea what ditra is. :D

      • Joe

        Hey Greg, Roger is metal on target. I even got burned with bad advice from the guys (a tile store), who sold me the Schluter products. I ask them why they were selling the stuff when they were not listed as an authorized Schluter dealer. Their answer… we’re working on that…… Roger’s books on employing Kerdi and Ditra are a few bucks well spent, and a great augmentation to the manufacture’s protocols. By-the-way you will use modified thinset if you install Ditra over plywood, and u.m.t. for the tile…… As you can see Roger, I’ve upgraded from chocolate milk to Jack & coke. Joe

        • Roger

          Thatsa good upgrade Joe. :D

  • Joe

    Roger, thanks for the timely response. No Kerdi-fix within a 100 miles, and very limited understanding of Kerdi installation protocols….. So your book really helped out. I’ve been given more bad information than good locally, to include the guys at the tile store where I bought it. Will have to rip out new cb because I was told to latex paint prime the cb board to stop it from sucking out water from the D-25 u.m. thinset. Durabond Engineer was very empathetic but said u.m would not bond. Kerdi Engineer said shouldn’t be a problem with the install. PermaBase cb Engineer said rip it out, can’t be fixed. Could go on, but my 2 typing fingers are tiring. Sika Flex has 20 or more bonding and caulk products. Which is the best caulk for changes in plane, and which bonding agent for the kerdi- tub flange seal / repairs?. This is really important as I’m going with drywall….. No free do-over if it leaks. Thanks for your help.

    p.s.: Any sentence that ends with “should be ok” generates doubt.
    Tears in my chocolate milk today……

    • Roger

      The flexible sika flex, can’t remember the name of it offhand. It’s one of the adhesives. The only place you need to use it is at the bottom of the kerdi where it ties into the tub flange. Everything else is covered and tied together with kerdi – no need for it in the corners or anywhere else.

  • Joe

    Rodger. A pic in your “how to kerti” book showed dynaflex 230 being used on the tub flange. Is this acceptable for sealing the kerdi to the tub flange, or just filling in the cracks? If it’s not a kerdi fix equivalent, what is?

    • Joe

      Sorry about the typo Roger…..

    • Roger

      Hey Joe,

      It is acceptable, but not the best choice. If you don’t have kerdi-fix you can use sika flex. It’s in the concrete section of the big box stores.

  • Donna

    Hi Roger,
    We’re installing a new tub/shower combo with a wide niche and are thinking we’ll go with the Kerdi for waterproofing. Two questions:
    1) Similar to another post, we’ve got large format white tiles 10×20 that don’t come with bullnose. One way or another, we’ll still see the rough edge of the tile – either on the wall tile, or in the niche. Any other products that you know of that can be used to line the edges of the niche?
    2) Our ceiling in the tub shower area is 10 feet tall. We’re gonna tile all the way up to the ceiling, but do we need to go all the way up with the Kerdi as well?

    Thanks again for all of the advice on your site – so far neither of our dogs have caught on fire!! :dance:

    • Roger

      Hi Donna,

      1. Schluter has many edge trims that can be used at the edges of your shower and around the niche.

      2. As long as you are six inches above the shower head you’re fine.

  • Tim

    I need to waterproof my shower which contain three niche’s. I’m very interested in the kerdi system however i’m a little concerned about using it to waterproof a niche, particularly the inner back corners of the niches. The niche templates provided have me cut, fold and over lay the kerdi so that if fits in the niche. However, as with any flat object cut to fit in a square hole, the manner in which the corners are cut technically leaves a small pin whole in the very corner where the 3 sides come together. This pin holes concerns me of course. People who do this online seam to have no issue with this fact. What do you say?

    • Roger

      Hi Tim,

      I have no issues with it either. If it makes you feel better get some kerdi inside corners and install them first, then install the templated piece. The inside corners are formed with one piece with no pin holes.

  • Dave

    Great description and photos! I am planning to pre-cast ceramic recessed shampoo and soap shelves inset into the wall. I’m not planning to finish out the niche in cement board, just the cutout required, but want to make sure to maintain the membrane seal. How would you recommend handling these with the Kerdi membrane?

    • Roger

      Hi Dave,

      Just run a bead of silicone or kerdi-fix around the perimeter of the cutout behind the flange of the niche.

  • Jonathan

    Is there any reason the wall tile can’t cover the edges of the niche tiles which comprise the top, bottom, and sides of the niche? I’m about to remodel our bathroom in a modern style with large format white tile for the shower/tub surround and I think that would look more “finished”.
    – Jonathan

    • Roger

      Hey Jonathan,

      No reason at all. Whichever way looks better to you is the correct way. As long as everything is waterproofed properly you can install it any way you want.

    • Jonathan

      Quick question regarding waterproofing. I will be bringing Permabase down just short of the the tile flange on my tub. See a very clear picture of what I’m doing here: http://hostedmedia.reimanpub.com/TFH/Projects/FH09OCT_BACBOA_01.JPG

      In this installation, is poly sheeting behind the Permabase (continued down in front of the flange) a more reliable waterproofing method than a siliconed joint and topical Redguard? If I use poly sheeting, what is the best way to waterproof the tile niches? Leave enough poly loose in the stud bay to accommodate the niche? Redguard just the niche?

      Love your tile tips eBook! Definitely worth the small cost.

      – Jonathan

      • Roger

        Hi Jonathan,

        Great picture! I need to find out who to ask to steal that. My customers won’t let me cut their tubs in half. :D

        The redgard is a better method. With the traditional the permabase will become saturated and remain that way. It gets flushed through when new water enters the substrate, but it’s normally always moist to some degree. With redgard you don’t have that problem – water hits the membrane immediately.

        If you use the traditional method you can either cut out your opening in the backer and the membrane and silicone the membrane around the perimeter to the back of the wall substrate. You would then redgard the entire niche. You can also fold and overlap and silicone a separate piece of poly around the back of the niche then overlap and silicone it correctly to the wall membrane – that one is time consuming and a pain, though.