Previously I’ve shown you how to build a shower niche using backerboard (or drywall) and Schluter’s Kerdi membrane. I did it that way for years – and still do on occasion. However, I have discovered a way to create a niche very easily with much less work and time involved – Kerdi-board.
For the purposes of this post you will need 1/2″ kerdi-board (3.5-4 square feet for a 2′ x 1′ niche) and a tube of kerdi-fix. Kerdi-fix is a urethane sealant made specifically for kerdi products and waterproofs seams. I am building a 2 foot high niche by 1 foot wide.
Begin by cutting all the pieces to the appropriate size. The piece for the back of the niche will be the largest – 24 1/2” x 12″. When assembled this will give you an inside dimension of 24″ x 12″ x 3 1/2″.
The next two pieces will be your sides. They will be 24 1/2″ long by the depth of your wall cavity wide. For instance: if you have 1/2″ substrate around your shower and your wall studs are 3 1/2″ deep then your side pieces will be 4″ wide. So, in this case (and most cases) they will be 24 1/2″ long by 4″ wide.
The piece for the bottom of your niche will be 12″ long by 3 1/2″ wide (4″ wall cavity minus 1/2″ for the thickness of the kerdi-board).
The piece for the top of your niche will be 13″ long by 4″ wide. (It’s bigger than the bottom piece, you’ll see why shortly)
Mark all your cuts on your kerdi-board first to ensure your layout will work for the amount of kerdi-board you have!
With a niche the size of this one these are the pieces you’ll need:
Now grab your tube of kerdi-fix and your gun (it’s sold in tubes like caulk or silicone and used in the same manner) and place a bead about 1/4″ from the bottom of the back piece all the way across.
Placing your beads 1/4″ from the edges will center it along the edge of the 1/2″ kerdi board.
Then firmly press the back of the bottom piece into the bead of kerdi-fix you just put on there.
Then place a bead along one side and the bottom of your side piece on the right.
The side piece bonds to the sides of the back and bottom piece. Press that firmly into place.
Now do the same thing with the left side of your niche.
The top piece of your niche bonds to the TOP of both side pieces and your back piece. This way it is supported when the weight of the tile pulls down on it and it isn’t relying only on kerdi-fix to remain in place. (That’s also why it’s larger than your bottom piece)
Place a bead of silicone around three sides of your top piece and firmly press it into place.
Now take the back of your bottom piece and press it up slightly, just about 1/16″ or so. This will create a small slope on your bottom piece so water drains out of the niche and doesn’t collect in there.
Now go back around the inside corners with another bead of kerdi-fix to ensure that you have it completely water tight. I also install an additional bead underneath the bottom piece just
because I’m anal to be safe.
And there you have it. A completely waterproof box (once it cures) to make a niche in your shower.
The kerdi-fix must be allowed to cure overnight and you should set it somewhere it won’t get knocked around or moved. You can also use tape (gorilla tape works best) to snug all the pieces in place and hold them there overnight.
In my next post I’ll show you how to get it into the wall and turn it into an actual shower niche rather than just a waterproof box.
For now you need to work on getting all that kerdi-fix off your hands.
And your dog…
I have hardi backer up on the walls of my shower, looking to waterproof them. Kerdi membrane might be out of my budget is something like redgard or hydro barrier recommended on hardi? I did a test piece and you were able to pick and peel it off, I’m not sure if that’s normal for a membrane
Hi, Roger – this is great stuff!! I’ve been buying some of your books and am looking for one with ‘installation of Kerdi shower pan’ directions. Is that in the library anywhere? Thanks.
I haven’t written that yet, but I am planning an article about foam shower pan installations, that would be included since they are all essentially the same. It won’t be up for probably a couple of weeks, though, as I’m taking all the photos this week for the article and still have to write it in my short bouts of sobriety…
Where has this blog been all my life? Fantastic articles- very detailed and helpful! Thanks so much for sharing!
I want to tile the walls of my half bath all the way to the 9 ft ceiling with travertine. there is only a toilet and sing so moisture is not a big issue. The wall are primed drywall. The Tile shop says I need to install hardibacker over the drywall but I really don’t want the added thickness in a 5’8″ x 2’10” bathroom. They say the drywall may not be able to hold the weight of the tile. What do you say?
I say that’s bullshit. The SHEER strength of drywall is more than enough to support nearly any tile. You can go right over it.
Thank you. That saves me time, money and will look better.
Apparently, there is some debate going on as to how waterproof the custom-made niches made of Kerdi board are. For example, I read that “Schluter requires additional banding over the seams and penetrations for their Kerdi Board products.” What do you think of that? Is gluing the pieces together with Kerdi fix enough to ensure all seams are waterproof?
The kerdi niches are waterproof. What they are talking about it the seams on the ‘wings’ of the niche – the part that sits flush with the wall, and the penetrations of the screws that put it in place. Yes, a foam-to-foam transtion with kerdi-fix is completely waterproof.
Hi Roger. I purchased and downloaded your guide to using a topical membrane on a tub surround. To make the footwall plumb I will have to fur out the wall about 1/2″ inside the inner side of the tub flange. Your guide recommends using drywall shims. In this case should the shims lap the flange to within 1/8″ to 1/16″ from the tub deck in order to support the CBU?
Ideally yes, but once installed there should be no pressure on the cbu in that area so it’s not really necessary.
Hey Roger – I’m still working on my shower surround (Too much beer). Anyway, I have a new question. I understand that corners are to be filled with silicone and that thinset and tape are to be applied over the silicone. Is that correct? My concern is that the thinset will not adhere adequately in these areas.
The thinset won’t bond to the silicone, and it doesn’t have to. It bonds to the backer and the tape to tie the two planes together. The silicone is in there to both compensate for lateral expansion (swelling) and to keep thinset out of that corner gap.
Remodeling a bathroom with a shower. I have installed durock such that there is about a 3/8″ gap between the lower side of the durock and the mud bed. Is it necessary of recommend to fill this gap before I apply redgard? If so want do you recommend to fill the gap with. Enjoy you site (even the attempt at humor).
You need to fill it with something. Deck mud would work, as would backer rod. You need something to paint the redgard over for a seamless transition from the wall to the floor.
Attempting my first Kerri board niche. Above explanation and photos are perfect. Just one sizing question. When tiling I’m planning so that the top of my tile is inline with the top of the bottom board. This will line up my grout lines for the bottom niche tile and wall tile. I’d do the same at the top of the niche. To have this happen, I need to leave 3 grout lines of 1/8″ and then 2 tiles of 11 7/8″ which would mean inside dimension of 24 1/8″. Does that seem correct or have I missed something?
Thanks again for all your help and guidance.
That’s correct for the inside dimensions of the kerdi-board. You need an extra inch to each measurement for your framing (one 1/2″ piece of kerdi-board on each side – extra 1″)
Fantastic information, your whole site is a treasure.
we are just about to jump into a new shower install, and I wanted to build and install a niche.
The only thing is – it is IMPOSSIBLE to find Kerdi-Fix in Canada – I’ve looked in every hardware store possible. They all keep the boards but not the sealant, I don’t get it. Retaillers (from the Kerdi website) only sell to contractors, it seems.
My only option would be a single guy who will sell me a tube on ebay (and 20$ for shipping)…. Poo.
Is there another option for sealant? Something from the Sika line maybe?
Meanwhile, I’ll keep on searching
Sikaflex construction adhesive works fine. And $20 is actually a good price for kerdi-fix, unfortunately.
She said $20 just for shipping. It’s $45 at the Home Depot. What’s so special about that stuff. I looked at a Prova brand niche (which looks exactly like yours only with a flange and costs $70), the caulk was sloppy and looked and felt just like Quad Sealant. Window installers swear by the stuff.
The only thing special about it is the name on the tube.
Roger – Would you recommend using Kerdi-board for shower walls or stick with the cement backerboard and Kerdi membrane?
They both work well. I absolutely prefer kerdi-board.
I have purchased some of your bundles and they have been a tremendous help.
I am using kerdi board for my shower and already using Schluter’s pre-fab niche in one spot but, due to stud spacing, I need to come up with a custom solution for another spot.
The 2″ bonding flanges on the pre-fab niche make the install easy when already using kerdi board and would help me with a custom version since I have metal studs (not sure I can use your top/bottom 2×4 method). Also, I can’t bond the niche to the wall behind the proposed niche since the wall belongs to a common space of my condo complex.
Have you ever tried to replicate the pre-fab niche and make a custom kerdi board niche with a 2″ bonding flange? For example, either by creating flaps with partial cuts or by sliding (and kerdi-fixing) a kerdi board “ring” around the box? Any other ideas?
Thanks in advance!
I haven’t done it in a shower, but I have done it in my garage (mad tile scientist’s lab). You can utilize either of those methods with kerdi-board and kerdi-fix. Creating the niche and installing a square ‘ring’ around it is the closest, and easiest, way to replicate the stock niches.
Hey Roger ,
Great info, love the site, and I bought your books!
For the niche – apparently does’t require framing when using the Kerdi(?) I just want to make sure. Can you show some pictures of the actual installation?
I normally install a stud on the top and bottom of the niche. It’s isn’t really required, but when you’re pushing tile down (or up) as you’re installing it you may push a bit too hard and break the seam. I’ve only done that once. And photos, and installation…it’s all covered in the next post – ‘Installing a kerdi-board niche‘.
Roger: Great site. After constructing the niche, I would like to use a piece of matching granite from my sink counter top for the lower ledge of the niche. Any tricks or recommendations for this install. I plan to notch the granite to create small side extensions as well as a small overhang in the front. Thanks
No real tricks to it. Install the wall tile around the niche and cut the shelf to it so it sits flush. It gets bonded with regular thinset as well.
Thanks Roger. One other issue; I’m looking to install a matching sill for the shower install just like the niche. Do you envision or have you seen any problems with water marks or discoloration of the granite in this type of install. I realize that the granite must be sealed on a regular basis and should probably be wiped down after each use (sure, will get right on that each time!)but just from a general use, any problems? Thanks
The only problems I’ve seen are with hard water spots on dark or black granite. Nothing that can’t be wiped right off, though. The only thing that CAN NOT go there is green or serpentine marbles (they warp).
Very nice and looks a lot simpler. I looked into doing the walls in that stuff for my next shower. But last time I priced it, it was over $500 for a 4×8 board.
It’s great stuff! It’s around $3.00 a square foot now, just over $90 for a 4×8 sheet.
Nice. Gotta build one of those for my beer…er…shampoo.