This was the most bizarrely terrible shower construction I’d ever encountered.

So, it’s going to be a pretty long description encompassing what was wrong with the original shower design (with vids!), how that terrible design might’ve happened (a bit speculative), and finally how it was fixed without demolishing all of the existing tile (with tips!). That’s why the whole description is split into two parts.

If you’d like to skip straightaway to the fix description, then click away to part two. But if you’d like all the gory (and that’s literal) background details first, then read all the rest of this post beforehand.

The Symptoms

So, these clients had a large home near the Lakeway area of Austin. They bought the place in 2015, but the home was built in the early 1980s and had seen some renovations. One of these was a master bath renovation that’d been done just before the clients bought the home.

The master bath (on the second floor above a first floor laundry room) had a garden tub and a separate custom tile shower with large 2×2 -ft polished travertine tiles on the wall and bench, and 2×2 -in travertine tile for the shower floor.

The clients started calling contractors for a shower fix when water started dripping from the first floor laundry room ceiling. Suspecting that maybe the shower drain was leaking, the clients carved into the laundry room ceiling for a look. They saw that the PVC plumbing for the shower drain and drain trap was all fine, but that the second-floor plywood subfloor was (looking from below) completely saturated with water.

Running the shower showed that, sure enough, water was dripping from the underside of the plywood all around the shower base.

The Diagnosis

The first contractors on scene had apparently immediately started ripping up floor tiles and ripping into the shower curb, so there was a pretty good view of the problem to start with.

After ripping into tile, that first repair contractor diagnosed the problem as “a leaky shower” (duh) and told the clients that they’d need to tear out the entire shower enclosure to the studs and replace everything because the fiberglass shower pan waterproofing liner must have spontaneously cracked.

The clients then started searching for a second opinion and different options.

Now, here’s the thing on that. It can often be possible to completely replace a leaky shower base with proper waterproofing without replacing the entire shower. This can cost half the price of replacing everything to the studs.

Here’s Yer Problem — It’s A POND!

It was clear that there was some sort of fiberglass waterproofing pan at the shower base. But there was a weird layer of water just inside the lip of the fiberglass pan that apparently wasn’t draining out anywhere.

Normally, this would be a straightforward sign that whoever installed the shower drain and dry-pack cement base clogged up the shower drain weepholes meant to allow the moisture absorbed by the shower base to eventually drain away. But I’d never seen actual standing water resulting from clogged drain weepholes before. Also, the fiberglass waterproofing pan should’ve been completely packed with drypack concrete if it were a traditional shower base design.

Removing the shower floor tile only deepened the mystery (pun intended). In proper traditional tile shower construction, the shower floor tiles are installed with thinset on top of a concrete base layer (which is all set inside a fiberglass or PVC waterproof liner bonded to the base of the shower drain). But for this bizarrely constructed shower, some dopey installer had used liquid nails construction adhesive to literally glue the limestone shower floor tiles to a flat slab of what looked to be synthetic cultured marble.

This is not how you tile a shower floor. Not. At. All. See all the black charcoal-looking stuff in the pics? That’s mold. And, that’s why you do not use freaking glue to set tiles for a shower floor.

But then the demo got even more weird. Removing all the shower floor tile revealed that a continuous slab of synthetic marble was used for the shower floor underlayment. Cracking through it showed that yep indeed, it was a 3/4-in thick piece of (naturally waterproof) synthetic marble that had been cut to size. Which explained the glue. You can’t tile directly on top of synthetic marble, because thinset won’t stick to it.

Peeling back the first row of wall tile then revealed something even more bizarre — the entire shower was made from surface tiles glued onto a synthetic marble underlay. The tiled walls, the tiled bench, and maybe even the tile on the shower ceiling were all glued on top of slabs of synthetic cultured marble.

And then, cracking through the synthetic marble slab covering the shower base revealed this:

Literally a subterranean pond underneath the shower floor. Amazing. Truly a first.

Whoever did the work on this shower had done one thing (kinda) right — they had a thick custom-formed fiberglass waterproofing pan installed on the plywood subfloor and properly bonded to the shower drain assembly:

The fiberglass waterproofing pan didn’t have a preslope and wasn’t wrapped around the shower curb, but it was wrapped all the way up and over the top of the shower bench and was definitely watertight. So good job on that. The rest? Bizarrely terrible.

After getting the fiberglass waterproofing pan (mostly) right, the previous contractor had then used slabs of synthetic cultured marble as the tile substrate for the walls, the bench, the curb, and the shower floor. They used a bit of packed concrete around the drain assembly and in the corners to support the shower floor cultured marble slab. Then, they used liquid nails to ‘waterproof’ the seams:

And then? I guess they then discovered that it’s not possible to install tile directly on top of a synthetic cultured marble surface. So, as a workaround, they just used glue for all the tile before grouting everything and (probably) running away asap.

The final result was that it apparently took a couple years for enough moisture to wick through the tile and grout and through the haphazard glue ‘waterproofing’ in the synthetic marble seams to completely fill the fiberglass waterproofing pan below. At that point, each use of the shower resulted in water overtopping the low spot in the shower pan and getting dumped onto the subfloor underneath the shower curb. A few more months of that and the subfloor became saturated with moisture, at which point all additional water started dripping onto the first floor ceiling below.

The basic problem was the bizarre way that the previous contractor had constructed the shower to fail. You never never never ever build anything (a roof, an exterior wall, a shower, a sink, etc) that will see water without giving moisture that might leak in a way to evaporate back out.

This shower was constructed almost as though creating a subterranean cistern was the goal:

With a solidly waterproof fiberglass pan on the plywood subfloor and a solid slab of waterproof synthetic marble underneath the shower floor tile, all the water that wicked through the not at all waterproof seams along the shower base had no way to evaporate back out. As a result, there was literally five gallons of fetid standing water just sitting in the fiberglass waterproofing pan underneath the shower floor.

Bizarre.

The Logic?

It can be fun to try and CSI an explanation for weird demo reveals. What possibly could have resulted in such a bizarre trainwreck of shower install materials? Usually, there’s at least a perverse logic at work that can explain bad construction. Let’s work through the possibilities:

A Corner-Cutting Contractor?

This is usually the most common explanation for completely f-ed up ‘custom’ tile shower installs. Doing things properly costs money. Skipping crucial things (like waterproofing) saves money — for the contractor. I’ve seen this a lot for leaky showers that turn out to have been installed with substandard waterproofing or even no waterproofing at all.

But that wouldn’t explain why a contractor needlessly paid ~$750 or more to have a custom fiberglass waterproofing pan installed. It’s completely buried underneath the shower base, which is why waterproofing is normally the very first thing that shower contractors skimp on. The waterproofing (or lack of) is literally buried out of sight, so why would a dopey contractor make needless waterproofing so expensive?

It also wouldn’t explain why this contractor chose to use synthetic cultured marble as a substrate for the tile. Normally, a bad corner-cutting contractor would simply use cheap (and easy to work with) regular drywall for the tile substrate. Since tile and grout aren’t waterproof, the drywall substrate will eventually get saturated with moisture and turn into a moldy crumbly mess. But, that usually takes at least a few years to become apparent (long past when a shady contractor has been paid and disappeared).

Synthetic cultured marble is expensive expensive. So, a typical corner-cutting dopey contractor explanation definitely didn’t fit this case.

A Confused DIY-er?

This is generally the second most common explanation for completely f-ed up projects. There’s a lot of things you can learn from a bit of research and some YouTube vids. But, not everyone understands and follows directions well.

So, I could imagine a scenario where the previous homeowner perhaps got tired of their synthetic cultured marble shower interior and decided to change it to a ‘custom’ tile shower using limestone tiles glued onto the synthetic marble walls and floor.

But this explanation also doesn’t explain some key details. For example, where is the effective silicone sealant that the previous synthetic marble installer would’ve used to waterproof the seams? And, even assuming that a DIYer mistakenly thought it’d be a good idea to carefully scrape out existing sealant for replacing with a bead of liquid nails, there’s the matter of the substrate condition.

The synthetic cultured marble that was used as the substrate in this case had no surface finish. When used for showers or tub surrounds (or countertops, or accent pieces, etc), cultured marble gets a surface treatment and polish to make it look like, well, marble. Like this example:

Yet in the client’s shower, the synthetic marble substrate was completely unfinished (discolored by glue residue and water stains, sure, but not polished to either a gloss or matte surface finish). More importantly, it was also shot through with screws to secure the synthetic marble panels to the wall studs:

There’s no way that anyone would drill screws through their marble walls for a ‘finished’ surface. That’s why proper cultured marble shower installers use silicone adhesive to secure the backside of synthetic marble panels to wall studs when making a shower or tub surround. Also, why would the original cultured marble shower installer have spent half a grand or more to have a custom fiberglass waterproofing pan installed just to install a waterproof synthetic marble shower surround on top of it?

So, the dopey DIY-er explanation also just didn’t fit the facts.

A Fraudulent “cost-plus” General Contractor!

Here is an explanation that does (unfortunately) fit the facts. Construction that uses a maximum amount of needlessly costly materials installed in a maximally useless way? Sounds like a cost-plus job.

Here’s a primer. There are several common ways that conventional general contractors cost renovation projects. The most common are: 1) Fixed price, 2) Labor plus materials, and 3) Cost-plus. This article gives a pretty clear definition of each.

Point is, there are different ways that a fraudulent general contractor can burn customers on cost no matter what kind of pricing they use. But, for renovation projects where labor is subcontracted by the general and materials are directly billed to the customer, “cost-plus” pricing offers a veritable wonderland of cost markup opportunities for unscrupulous operators.

Here’s a (*cough* theoretical) example. Say you have a contractor who sells you on the idea of hiring them because they offer “only” a 15-20% fee on top of direct labor and materials costs. On paper, that would be a great deal. The average added general contractor fee cost on a bathroom renovation project in the Austin, TX, area is about 30-40% over subcontracted labor and materials costs (which is not unreasonable for a traditional general contractor working in an overheated housing market).

So again, a general renovation contractor who promises to do a bathroom renovation project with only a 15-20% management fee markup (based on the total cost of subcontracted labor and materials) is a great deal so long as the general contractor isn’t completely fraudulent about padding the labor and materials.

But if the general contractor is a complete fraud with the sole goal of maximizing their own underhand profit, then here’s a (*cough* hypothetical) example of how they could charge a client thousands more than necessary for a completely f-ed up shower remodel:

Step 1: Get the client completely confused about how to construct a properly waterproofed shower. This generally isn’t too difficult, since there unfortunately aren’t a lot of very clear descriptions on the interwebs for all the different shower waterproofing options. So, sell the client on the idea that if using one waterproofing strategy is good, then using three waterproofing layers must be better. (it isn’t, btw)

Step 2: Use as much expensive material as possible in doing the job. Fiberglass shower pan for no practically useful reason? Sure, use that! Synthetic cultured marble as a surface just to glue tile to? Sure, why not! The more expensive (albeit unnecessary and useless) the material, the better!

Step 3: Subcontract the install labor to idiots (explains the liquid nails). Pay ’em minimum wage (in cash — no paper trail). Then, charge the client a $30/hr rate per ‘expert’ installer.

Step 4: Cash the client’s check and run away as quickly as possible, so you have time to fold your business LLC and open a new one before something like this happens:

And, that’s how you turn a $5,000 custom shower project (and a reasonable $750 fee for managing the weeklong install work) into a $15,000 total cost shower project (including $2,500+ for the general contractor’s “expertise”) using cost-plus pricing.

The Fix

The conventional approach to fixing any leaky shower is to rip everything to the studs and start over. I had done several previous shower fix projects by taking a less expensive approach of just replacing the shower base, and therefore saving money for clients by leaving all the tile from ~12-in up intact.

In this case, replacing just the shower base and first course of tile would be a real trick. But, it would also be a real significant cost savings, so the clients were game to try it.

Here’s the description of how that went: Fixing the Worst: part deux!