Let’s Make a Shower!

Because, showers are great. Every home needs a bathtub bath. But, if you’ve got two or more bathtubs in your home and no walk-in shower, then you’re just not living life to the fullest.

Is it easy to convert a tub to a walk in shower? Not necessarily. But is it super difficult? Usually not. Worst case, you may need to get some jackhammering done to widen out drain access through a concrete foundation. And, smacking a cast iron tub into pieces for demo removal will take awhile. But compared to a long gym day, swinging sledges and pneumatic hammers offers the same workout with way more productive results.

The Situation

These folks had a very blah 1970s vintage standard tub and shower combo that both dated their home and was becoming a real drag to use as a shower:

It had no convenient storage for anything besides one bar of soap and a towel. And it had no design or character at all. These clients wanted to flip that and put a capital “C” in “Custom” for a shower designed by them for them.

The Plan

The clients had already sourced the tile for the exact design they wanted (vertical glass tile stripe, 4×12 ceramic tile also set vertically, and lowest curb height possible):


With a bit of extra advice on what was structurally possible (for ex, an inset niche in the showerhead wall being completely doable, an offset subway-style pattern being possible for even a vertical layout, etc), they settled on a firm list of final design criteria:

  • Vertical 4×12 textured subway wall tile
  • Vertical glass tile decorative stripe
  • Square mosaic 2×2 shower floor and curb tile
  • Niche inset conveniently located in showerhead wall
  • Side-by side controls for volume/temp and a handheld wand

Definitely a unique layout with the vertical subway-style pattern. And, plumbing the two mixing valves side-by-side with routing two showerhead risers around an inset niche would require some creativity.

But, that’s what custom shower creation is all about — making the unusual and unique things happen!

The Process

Converting a tub to a walk-in shower is conceptually pretty simple. The only significant potential difficulty is dealing with the drain placement and access. Tub drains are located 2″-3″ from the plumbing wall because that’s how bathtub basins are generally designed. However, that’s usually too close for an effective shower floor slope.

Also, attaching a shower drain to a tub drain stubout requires excavating down around the drain to make the new waste line connection. This can be difficult if the drain is set in a concrete slab.

But aside from those possible difficulties, the rest of the process is very straightforward:

  1. Demo the existing tub and tub enclosure down to the studs and subfloor/foundation
  2. Attach a shower drain to the existing tub drainpipe and redo the supply plumbing (new mixing valve, etc)
  3. Frame the shower curb and install backerboard for the tile install
  4. Install a properly sloped shower base and waterproofing throughout all the shower wet areas
  5. Install the tile and grout
  6. Finish with the shower trim (mixing handle, showerhead, etc) and install a shower curtain or glass partition/door

So, very straightforward in theory. In practice? Read on to see…


Sometimes, it’s possible to salvage the tub in a tub to shower project. If it can be lifted up and fit through the bathroom door in one piece, then the tub can be donated for future re-use. Unfortunately, most used acrylic tubs are too scratched to make re-use possible (especially since new acrylic tubs are pretty inexpensive). And, nice sturdy cast iron tubs are almost always too heavy (like, nearly a quarter-ton heavy) to make re-use practically possible.

So, unless you’re removing an enamel on steel tub with a finish that’s in great shape, plan on a sledgehammer demo.

That was the process on this project. The bathroom was originally built around a super-heavy cast iron tub that was too large to fit through the bathroom doorway (the original builder had likely installed the tub before even finishing the bathroom framing). So, hammering it into pieces was the way to go.

The nice thing about cast iron is it’s brittle. Whack it with enough force and it’ll shatter into pieces. The only bad thing is any enamel coating on the cast iron will shatter too — into little teeny flying shards. So be sure to WEAR FULL GOGGLES and longsleeves, long pants, etc when trying this trick at home:

Finishing up the demo and removing all the debris revealed this for the tub drainpipe and supply plumbing:


Normally, that’d be a foundation slab opening just large enough for attaching a shower drain and p-trap just far away enough from the wall to get an effective shower floor slope.

But, not in this case. Since the original plumbing was done in the 1960s, the tub drain was made from 1-1/2″ copper pipe. Modern shower drains are sized for 2-in PVC waste pipes.

So, attaching the new PVC shower drain required excavating down to a main 2″ or larger section of the main waste pipe. This in turn meant widening the existing concrete slab opening enough to get some working space. Damn disappointing, that. The solution?


If the existing opening in a foundation slab isn’t big enough for what you need, then simply make it bigger. Not a fun job (since hammering through 8″ thick hardened concrete is a slow, sweaty, messy, dusty process). But, totally doable with the right tools.

These are the right tools:

After a day of cutting through 10+ inch thick super-hard concrete and rebar with a 30-lb hammer rental, the opening was just large enough to accommodate all of the new drain plumbing:

As an added benefit, making the access opening larger also made the new shower drain location more convenient. The new drain was now centered a full 12-in off the finished wall and only 1/2″ off the concrete slab, which made both the final shower floor height and slope far more conventional.

Framing and Plumbing

The framing carpentry was thankfully more straightforward. The original studs were still sound despite the original tub surround wall tile being installed directly on drywall. So, there was only a need for some additional framing for the niche inset and added wall studs all along both ends of the new shower curb in case the clients decide to install a glass divider in future.

The supply-side plumbing, on the other hand, was not straightforward. The clients were wanting to install not just a conventional mixing valve control (the valve that mixes hot/cold inputs to get the desired temp water out of the showerhead) but also a diverter valve control for a separate handheld shower wand. The conventional install pattern for this setup is to install the diverter valve directly above the mixing valve, like this:

piping diagramThis custom install, however, was complicated by two things. First, while putting an inset niche in the showerhead wall is definitely super-convenient (since it puts your shampoo bottles, etc, right in front of your face), it requires making a jog in the showerhead riser piping and also crimps the space available for multiple-control shower setups. And second, while shower diverter valves are designed for a stacked plumbing install, the clients really wanted to place the two controls side by side.

So, the final supply-side plumbing ended up looking a bit Rube Goldberg -ish:

Not the straightest piping plan (literally), but being able to make even the most roundabout of water paths happen is just yet another advantage of working with PEX piping and fittings.

Backerboard Install

The concrete backerboard and sloped base installations required far less thought than the drain and supply-side plumbing. There were still some details that needed careful attention.

The first was to take the extra time to properly seam and spackle the concrete backerboard seams with thinset. RedGard waterproofing goes on pretty thin, so it can’t fill seams or open corner gaps. It can, however, very effectively waterproof a backerboard surface that’s prepped like this:

And again, the advantage to jackhammering out a drain placement further from the wall was an easier location for managing the concrete base shower slope installation:

With the Kerdi drain nice and low to the concrete foundation slab, there was only a few inches of drypack concrete needing to be installed for the base slope.


This install got Kerdi fabric waterproofing for the base and shower curb, and paint-on RedGard waterproofing for the walls.

Here is a pic that shows what a nice, thick, effective layer of seamless RedGard waterproofing looks like when ready for tiling:


And, these pics show what an effective Kerdi install looks like when used in place of a more old-school shower “pan” for effective shower floor and curb waterproofing:

Putting the waterproofing directly underneath the tile really minimizes the amount of moisture that needs to evaporate back out from the shower base between uses, which makes for a super mold-resistant shower install that will last for half a century or more.


Clients are usually really surprised at the amount of prep work that needs to happen before even the first bit of tile goes on a wall for a custom shower install. But, once the waterproofing is all done, the actual tile installation usually goes pretty quickly. For this install, though, the tile install took a bit longer than usual:

The main tile install challenges on this project were twofold.

First, the clients were super-excited about using a very unique type of glass mosaic for the vertical accent strip. This mosaic was made from tiny irregular pieces of tumbled glass:

Installing this on a vertical wall to achieve a flat finish with dead-even border grout lines on both sides took a bit of extra time. I could describe precisely why in detail, but that’d probably get me in trouble with the tilesetter mafia. Instead, I’ll just post these pics of the pre-grout result:

Second, the clients decided to use 2×2 square shower floor mosaic tile on the shower curb as well as the shower floor to achieve a neat-o visual effect. With no bullnose to work with, this required fitting metal edging strips with precision:

It took some time, but the result was a dead-level curb tile install with just enough inward pitch to ensure that it wouldn’t collect any standing water:


Installing grout is always messy and a real pain in the elbows. But it’s still my favorite step, because it means that a project is really close to being finished:

Remember that grout is not waterproof. Neither is tile, actually. That’s why it’s critical to properly waterproof the substrate underlayment in a shower or tub surround. The grout in a shower or tub surround is actually practically mostly just for aesthetics and convenience (since trying to clean soap scum film from ungrouted tile would be pretty annoying).


The Finish!

With the grouting install done, the final step was to put on the fixture finishes and treat the shower floor tile and grout with a good penetrating sealer. Again, this doesn’t make the shower floor tile and grout waterproof — the Kerdi waterproofing fabric barrier underneath the tile and grout does that. But, applying a quality sealant to the shower floor does then make it much easier to keep clean of soap and oil residue — a good value for just an extra $20 and 30min of effort.

So, sealant application and fixture trim install (mixing valve cover and handle, showerhead, etc) is the victory lap step of any custom tile shower project. The before and after views of this install were particularly dramatic.

The Result?

Very happy clients! You can read the review here:

Read Chris S.'s review

For an objective visual evaluation, here is the conventional before/after compare and contrast.



And, after:

The clients designed a really attractive and practical shower space with supercool materials. Yay happy super-stylish showering!