Building a niche with Kerdi-board

by Roger

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:

sizes for nicheInstalling the bottom pieceNow 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.

Bead along the back and bottom of the side piecesThen 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.



installing the right sideThe side piece bonds to the sides of the back and bottom piece.  Press that firmly into place.



sides and bottom done



Now do the same thing with the left side of your niche.



Top piece placedThe 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.


Creating the slope on the bottom pieceNow 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.

Full bead of kerdi-fix inside cornersBottom waterproofed on both sides


And there you have it. A completely waterproof box (once it cures) to make a niche in your shower.


completed niche

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 arms.

And clothing.

And your dog…

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Hi Roger,
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″)



Hi Roger!
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 ;)



Hi Mymy,

Sikaflex construction adhesive works fine. And $20 is actually a good price for kerdi-fix, unfortunately. :D



Roger – Would you recommend using Kerdi-board for shower walls or stick with the cement backerboard and Kerdi membrane?



Hi Richard,

They both work well. I absolutely prefer kerdi-board.



Hello Roger,

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!



Hi Matt,

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?



Hi Michael,

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‘. :D



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



Hey Don,

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.



Hey Chris,

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. :lol2:


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