One of the problems with waterproofing a shower is the fact that you NEED to have holes in it. The cutouts for the shower head, shower or bath controls and any other fancy stuff you saw in that magazine. The problem with holes in a waterproof shower is that they make it not so waterproof.
So how do you waterproof a hole? (Please DO NOT email me with the punchline to that joke!)
Whether you have utilized a topical waterproofing like Hydroban or Redgard (liquid) or Kerdi (sheet), or you’re using the traditional method with a membrane behind your substrate, the answer is silicone. You need to use 100% silicone, none of that acrylic silicone or any of that stuff that sounds fancy (but doesn’t work long-term).
First a little about silicone. A lot of people ask me which silicone is best. For the purposes of most shower applications silicone is silicone. If it’s 100% silicone there isn’t (for all intents and purposes) any difference at all. They are all the same. Just grab a tube of silicone and stop overthinking it!
Now once you get your hole cut out in your tile flip it over so you’re staring at the back of it. Have a
beer Pepsi to congratulate yourself for such a fine looking circle! (Picture 1)
If your hole spans two or more tiles then the technique is the same, but you should have two
Now all you need to do is shoot a large bead of silicone all the way around the perimeter of the hole. (Picture 2)
You can click on any of these photos to view a full-size version.
When you comb thinset onto the substrate you want to scrape away the area around where the hole in the tile is. (Picture 3)
This will ensure there will be full contact between the tile and substrate.
Then just slam your tile up there.
Okay, don’t slam it up there, place it up there carefully and press firmly to ensure full contact.
What this does is create a dam of silicone around the perimeter of your cutout. When water gets behind your tile (and water WILL get behind your tile!) and runs down the wall, it will run around the bead of silicone and continue down the wall into the tub or shower base and into the drain.
If you want to, pull the top of the tile back off and check to make sure you have complete contact with the silicone bead and the shower substrate. (Picture 4)
If you get enough silicone on there you’ll be able to run your finger along the perimeter of the cutout after you install your tile to smooth the silicone. It’ll be a mess – just like picture 5.
Once you get your escutcheon (the metal cover plate) on there no water will enter through the front of the tile, then any water behind your tile will run around the dam.
You can also do this with the cutout for the shower head if you want to, but it’s not as imperative up there. It never hurts, though.
If you are using the traditional method and have your waterproof barrier behind your substrate (like in these pictures) you’ll need to silicone the perimeter of the barrier to the back of your backerboard. This creates the same waterproof dam on the backside of your substrate as well.
I do not have a picture of that. Because I’m a slacker. Get off my ass about it.