When you build a shower you will eventually need to make some holes in it – it’s just part of the overall process. You’ll need to install frames or hinges for your shower doors, grab bars, shower curtain rods, a picture of your pet iguana – whatever. The problem is that now you have that completely waterproof shower you really don’t want to go poking holes into the waterproofing.
No matter which waterproofing method you’ve used any fastener penetrations will have to punch a hole into it. You want to make sure you install your screws properly in order to maintain the integrity of the waterproofing. You don’t want to ruin all your hard work because you need to drive a screw through it!
The first thing you need to do is mark the exact locations of your screw holes. Most things like grab bars come with little templates you can hold up and get exact placement. With shower door frames and stuff like that you can hold up the frame piece and mark the correct location.
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.
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.
When using Kerdi for your shower floor you need to make a hole in it for the drain. If you don’t then you simply have a shallow swimming pool rather than a shower. This hole must be the exact size and it must be in the correct spot. There are two ways to do this.
The first way is to install your membrane on the floor then cut out your hole for the drain. While this method works, I’m not a fan. It leaves open the possibility of cutting more than just your membrane (where it needs to be cut), slipping and damaging the drain or messing up the bond of the membrane around the drain where you need it to be bonded (accidentally debonding a portion of the membrane while you’re cutting the hole).
It works, but there’s a better way. I’m assuming here that you’ve already cut your hole in the floor, installed the drain and mud deck and cut your kerdi membrane to the correct size for your floor – the width of your floor plus four inches, by the length of your floor plus four inches. That is your floor size plus two inches up each wall. Got that? Good, let’s move on.