This post describes the process of fixing a remarkably badly done shower install. If you’d like the demo diagnosis background for this project, then check out Part Uno. If you’d instead just like to see how to install a completely watertight shower, then read on!
The Material Challenge
Folks often mistakenly believe that tile is waterproof. While some types of tile are indeed nearly waterproof, no tile is completely water tight by itself. This is why tiled showers need a waterproofing layer built into the construction.
For this shower construction, the clients chose travertine tile with a honed surface. ‘Travertine’ is a fancy word for “tile made out of limestone”. If you live in Austin, then you know that limestone is almost as watertight as a sponge:
It does look really nice for a midcentury-modern “Fallingwater” look though, and in this case it also didn’t argue with the slate and imitation stone tile already installed in the rest of the bathroom:
So here’s the thing with crafting a shower using porous natural stone tile — DO NOT simply put up concrete backerboard for the walls and start tiling. Concrete backerboard will also absorb moisture, so putting two water-absorbent stone and concrete layers together is a recipe for ensuring a musty, moldy, always damp mess.
Instead, use an effective waterproofing layer to ensure that the moisture absorbed by the stone tile will not go any further than the tile layer (and therefore completely evaporate back out between showers). In other words, do this:
With everything already demolished down to the studs and concrete subfloor, the install plan was straightforward:
- Re-frame the shower walls for extra backerboard support and for adding niche storage plus a footrest
- Hang 1/2-in concrete backerboard for the shower interior substrate
- Install new drain plumbing and a properly sloped concrete base
- Install KERDI waterproofing for the shower floor and curb, and then install “Silka” brand masonry caulk and RedGard waterproofing for the shower walls
- Re-tile the shower floor and walls, grout, and re-install the glass shower door and partition
If you’re an experienced DIYer or tile professional, you’re probably thinking that there’s a “seal the tile” step missing. But that’s intentional. Since the travertine wall tile was honed and polished, it wasn’t necessary to seal the tile in order to prevent grout from sticking too much to the tile surface. In fact, since the clients chose to go with a brown grout for their brown tile, a bit of grout filling in the tile surface pores was actually a benefit.
Advice to seal travertine tile for shower installs only really applies to situations where you’re installing the tile on concrete backerboard with no waterproofing layer. If you’re depending on the grout and tile to be your “waterproof” layer, then applying many many coats of a good penetrating stone tile sealer is indeed your only hope for having a (kinda) dry shower for at least a year or two.
But, if you just put a thick layer of RedGard under the wall tile, then it’s actually counterproductive to seal the surface of the shower wall tile. Even sealed tile will still absorb some moisture, and a surface sealant makes it more difficult for this absorbed moisture to then evaporate back out once it gets behind the tile. Leaving natural stone wall tile unsealed actually helps the shower to dry out more quickly between uses so long as it’s installed on top of a good waterproofing layer.
The Waterproofing Install
Speaking of, here’s what the RedGard and Kerdi waterproofing looked like after install:
And, if you’re skeptical about how well Kerdi actually works for waterproofing a shower floor, here’s a video of the flood test (filling the shower floor with standing water to test for leaks):
Kerdi is pretty awesome for bulletproof waterproofing.
The Tile Install
In addition to large-format limestone tile for the shower walls, the clients decided to include a very creative vertical glass tile accent strip. Since the glass tile mosaic wasn’t the same thickness as the limestone tile, this required a bit of skill to make the whole thing flush:
The clients also chose to replace the previous shower bench (not a great choice for a small shower space) with a small wall niche placed 18-in or so up from the shower floor. This would make for a very convenient footrest for easy leg washing and shaving:
Finally, the clients chose to use a natural-looking river stone pebble mosaic tile for the shower floor (inspired by a New Mexico spa shower). This required some work playing around with different mat placements to make the seams completely seamless, but wasn’t too difficult:
The tile install itself went smoothly. The large format 12×24 -in wall tiles were flat enough to use just 1/8-in grout lines for a nice euro contemporary look. And, since the limestone tiles were mostly solid, there wasn’t a need for outside corner trim:
The biggest wall tile install challenge was pre-planning the layout to ensure that there wouldn’t be any wonky-looking grout line placement. Doing a subway offset pattern in a small shower space with several niches takes some thought and care:
If you just start throwing tile on the walls in hopes that it’ll all work out in the end, you’re likely to be disappointed. Plus, doing all the layout thinking beforehand generally makes the actual tile install go much faster.
The Glass (re)Install
Originally, the shower had a frameless glass door and two-panel glass partition for the outside half-wall. Since frameless glass door and partition panels are custom-cut to precisely fit custom tile shower installs, the conventional approach for a complete renovation is to simply completely replace the glass with new custom-cut pieces.
But, custom cut and professionally installed 3/5-in thick tempered safety glass is really expensive. In this case, it would’ve cost the clients $1,000 or more just to replace a door and two glass half-panels. So, whenever doing a shower rebuild I always try to match the original shower doorway dimensions to within 1/8-in so as to make re-using the original glass a possibility.
Doing this successfully is actually pretty tricky, since it also requires making the new shower doorway match the precise plumb of the original. Not easy when you’re ripping all the original work back to the studs and completely starting over. But also not impossible. I’ve gotten pretty good at pulling off this trick:
This install continued my so-far perfect glass re-use record.
The Final Result
Although the shower glass reflections made taking final result pics a bit challenging, you can hopefully still judge the before versus after results for yourself.
And, if the pics don’t speak for themselves, then you can check out the client review here: