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:
Placing your beads 1/4″ from the edges will center it along the edge of the 1/2″ kerdi board.
Then place a bead along one side and the bottom of your side piece on the right.
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…