Super Shower TWO: making the shower

This is the second part of a detailed spa shower creation description. If you’d like to read about all the design, demo, plumbing, carpentry, and other prep steps then just click on this “Super Shower ONE” link for the gory deets. But if you’d instead like just the tasty dessert description first, then read on!

FINISH STEP ONE: Sloping the Shower Floor

With the plumbing in place and the walls all buttoned up, the first step to creating an actual usable shower was to install the sloped concrete base. I’ve described the details for what kind of concrete mix to use, what thickness works best, and other info in this previous post. So here are just a few pics to show how some basic tips and tricks can result in an effectively sloped shower floor base for even a very large spa shower:


How to make an evenly-sloped floor for a very large shower where you can’t reach all the corners at once? Simple — just install, pack, and slope the concrete by working in successive pie-shaped sections. Kinda like painting a long narrow closet floor, simply make sure that you end at an exit (or use some plywood or drywall pieces for stepping on):

And just like any drypack concrete shower floor slope install, just ensure that you’ve got an even 1/8-in to 1/4-in per foot of run from the drain with the aid of a basic bubble level and some straight MDF trim guides cut to whatever lengths are most helpful:

And as always when shaping concrete just be slow and patient. Drypack concrete that’s properly mixed to the consistency of sandcastle sand is very forgiving. Grabbing a handfull (or a dozen handfulls) of mix from high points and packing them back down to fill low points to even out even a very large shower floor slope is usually no more work than making a perfectly flat 3-ft by 9-ft sandcastle.

If at first it’s not perfect, just play around until it’s finally shaped well enough. Deck mud concrete mix is very patient.

STEP TWO: Waterproofing the Walls and Floor/Curb

This is also a step that I’ve previously described. Although this shower project was larger than most, the waterproofing basics were still the same with RedGard applied to the concrete backerboard walls and Kerdi fabric for the shower floor and curbs:

With the large window lighting, you can really see the hydrophobic qualities of the Kerdi waterproofing membrane after draining the shower from the flood test:


Want to ensure that your shower is completely watertight and mold-free? Put the waterproofing directly underneath the tile!

STEP THREE: Installing the Tile

The client chose to pay homage to the classic 70s finish elements of the rest of the house by both keeping the James Bond -esque wallpaper pattern on the original ‘his’ side of the bathroom and finishing the shower walls and bathroom floors and baseboards with gunmetal -inspired patterned grey porcelain large-format 1×2-ft straight edged tile.

To complete the design, the client chose a variegated manufactured stone mosaic floor for a full-on volcano lair spa shower theme.


Installing the floor tile was actually the trickiest challenge of the entire project, since it’s actually pretty difficult to install stone mosaic tile on a sloped shower floor without showing seams. And, the larger the shower the more difficult the install.

And this was a very large shower. While stone mosaic tile mats are engineered to ideally fit together perfectly, just the fact that a sloped shower floor is not flat makes even perfectly engineered mosaic mats no longer fit together perfectly. And, these mats were not engineered perfectly.

Which means that hiding these shower floor tile seams required some extra time and patient trial and error planning. First, this meant making sure to puzzle out the best fit for each specific mosaic tile mat (and then labeling each of them for install):

Then, using only a thin “scratch coat” of thinset for adhering the stone mosaic floor tile with a 1/16th -in v-notched trowel ensured a clean install with tiles that were still firmly adhered and ready for grouting:


Stone mosaic tile can get really messy if the thinset squishes up between the gaps and starts smearing the tops of the stone tile pieces. Also, it takes forever to pick out thinset from between stone mosaic tiles to prep the surface for grouting.

So, using just a thin layer of thinset to avoid both these problems will ensure a clean, level, and perfect final result.

STEP THREE-POINT-FIVE: Niche Tile and Trim

A true spa shower experience requires lots of shower products, which (ideally) requires lots of niche storage for body washes, hair conditioners, etc etc. So, this shower got lots of niche storage including a footrest niche for easy leg shaving:

Especially if your shower is narrow or just too small to easily fit a bench, seriously think about a 4-in by 8-in or so sized wall niche about 18-in off the shower floor. It’ll make foot washing and leg shaving way easier.

STEP FOUR: Grouting

The clients chose to finish the look with a neutral grey grout. While this was a very large shower with double the normal surface area and other features (literally two threshold entryways, three niche spaces, a window, etc etc), grouting large-format wall tile at least goes quickly:

Grouting the floor took quite a bit longer since a properly grouted tile shower floor requires two grout applications to really even out all the seams and ensure a happy barefeet experience:


A very long grout day, but then it was just a matter of installing the shower fixture trim for the project finish.

FINALE: A Whole New Space!

I worked on the structural rebuild and super-shower build-out and tile install, along with floor and trim tile throughout the two bathroom spaces. The clients worked to finish the rest of the bathroom themselves — installing two euro-style wall mounted vanities, fixtures, new lighting, etc.

By the time I was finished, the now connected master bath looked like this:

Quite a style and usability upgrade over the ‘before’ bathroom:

And the clients were really happy with the outcome, as you can read in their review HERE.