In my previous post I showed you how to make a niche for your shower out of Kerdi-board. If you haven’t read that you probably should. It’s gonna be really difficult to install a Kerdi-board niche if you don’t have one.
When I install shower niches I prefer for the edge of the niche to be lined up with the grout lines in the tile installation. This way it looks like it belongs there rather than looking like something that was an afterthought (I HATE that…). So it requires planning.
When I build my niche I make it the same size as the tile I’m installing (or a multiple of those tiles, like two tiles high by one tile wide). This will be the INSIDE dimension of your niche when you build it. So again – more planning.
For example: If my tiles are 12×12 and I want my niche to be two tiles high I will measure the exact dimension of two tiles high (with a grout line in the middle). You then want to ADD 1/4″ to that measurement. You can always build the tile out, you can’t make a tile fit into a space too small for it unless you cut it – then it will throw everything off.
If my tile is 11 3/4″ square and I’m using a 1/8″ grout line then the inside dimension of my niche is going to be 23 7/8″ x 12″ (11 3/4 (tile) + 11 3/4 (tile) + 1/8 (grout line) + 1/4 (extra) high) X (11 3/4 (tile) + 1/4 (extra) wide). It looks confusing, it really isn’t.
I will normally install my wall tile up to a row below where I want the niche. Once that’s finished I can draw level lines horizontally and vertically to determine exactly where my grout lines will be on the wall where the niche is being installed (or use a laser, ’cause I’m star-warsy like that…). Those lines are where the inside dimensions of your niche will be.
Using 1/2″ kerdi-board for your niche, you want to draw lines 1/2″ outside of your grout line markings. That way once you get your niche in there the inside dimensions will fall exactly on those grout lines. Now that I’ve completely confused the hell out of you I’ll walk you through it with pictures.
It is important that you know where your wall studs are located! The niche must fit between two wall studs. I normally mark them directly onto the wall substrate as I am installing it. In some of the photos you’ll notice a random blue mark on the right side of where the niche will be, other than the marks I’m indicating – that is where that stud lays inside the wall. You need to ensure that you are inside these marks with your niche.
You can click on any of these pictures for a full-size version.
This particular shower uses kerdi-board for the wall substrate as well, but you can do this with a regular kerdi shower or any other substrate if you can seal the wall waterproofing to the kerdi-board niche. Kerdi-fix works for this with any topical waterproofing, liquids can be painted directly onto the niche. Traditional waterproofing with a barrier behind your substrate does not work with a kerdi-board niche. It can be done, but I really don’t recommend it.
We begin with installation of the wall tile up to a row below the niche. This allows us to see exactly where the grout lines will be.
If you click on this picture you’ll notice a blue pen mark to the right of the vertical laser line (it’s near the crossing point on the bottom) and a mark 1/2″ below the horizontal grout line. This mark is 1/2″ outside of the grout lines, that allows for the 1/2″ thickness of the kerdi-board in the niche.
You want to draw a vertical line 1/2″ to the right of your grout line and 1/2″ under your bottom horizontal grout line all the way up past the top of your niche and all the way across the bottom.
Now line up the laser (or level lines) with the grout lines on the left side of the niche and the top of the niche. Make your 1/2″ marks outside of those and draw those two lines. In this photo the laser is lined up with those marks 1/2″ away from the grout lines.
Trace the outside of the niche onto the wall substrate. These will be the lines that you cut to create the space for your niche.
Then cut out the rectangle that you just traced around your niche.
Once you have the hole cut out place your niche in there about half way to ensure that the perimeter is big enough and it fits snugly.
Now you want to cut a 2×4 for both the top and bottom of the niche. Measure between the studs for each – they may not be the same size (depending on how consistent your wall studs are).
Place the 2×4’s in there and tap them in so they are flush with the top and bottom of the opening in your wall. Place two screws on the top and two on the bottom through your wall substrate to hold them into place. You can see the screws and washers holding the 2x4s on the top and bottom in the second photo below.
If you happen to push the bottom 2×4 too far down (that NEVER happens to me…) you can simply drive a screw into the center of it and pull it back up. Don’t tear your wall apart because it went down too far.
Now push your niche into the opening. You can use screws into the sides to secure it, kerdi-fix on the back of the niche will hold it in place as well. Once you get it in there it should be snug and unable to move around.
Once it’s all flush and snug finish waterproofing the transition from the wall substrate to the niche box, in this case I used kerdi-fix, and let it cure (it is NOT installed yet in this photo!).
If you’re using regular kerdi, kerdi-fix will work as does a band of kerdi over the edges. If using a liquid membrane simply paint it over the edge at least two inches into the niche and out onto your wall substrate.
That’s it. Now it’s all ready for tile. Provided you placed and cut everything correctly the inside edges of your niche should be about 1/8″ outside your grout lines. With thinset beneath the tile inside the niche it should line up perfectly.
You can read about how I install tile into the niche here: Building a niche for your shower Part 4.
It’s all the same thing – a box inside your wall. The tile is installed the same way whether you use kerdi-board, regular kerdi, liquid waterproofing like hydroban, etc.
I’ll leave you alone now since you have to go scrub kerdi-fix off of everything – again.
Tenacious stuff, isn’t it?