More Leaky Shower Fixing

Just about every month, I get calls from folks with the same problem. Their ‘custom’ tiled shower leaks water. Usually, folks first notice this as moisture wicking into baseboards next to the shower curb. Or, folks notice a musty moldy smell in an adjacent closet.

OR, the problem announces itself quite loudly with water literally dripping from the ceiling below a second-floor shower.


The Situation

This was a newly-renovated house-turned-duplex in the Hyde Park neighborhood of Austin. The client had bought the place as an investment, renting out one half of the duplex while living in the other. Both sides of the duplex were mirror images, with two full bathrooms upstairs. One bathroom had a tub, and the other bathroom had a full master bath with a newly installed walk-in shower.

Unfortunately, the tenant’s master bath shower started dripping water through the ceiling below just a few weeks after they moved in. And then the shower on the other side of the duplex started doing the same.

This is the danger of investing in a quickly flipped reno. Although custom bathrooms and showers can look great on the surface, the top layer of tile can hide lots of corner-cutting below. In this case, there was zero waterproofing for the shower base.

The Temp Fix

Ideally, you really want a proper effective waterproofing layer below the tile in a shower. But, if you have a super-leaky shower and need a quick fix, then here’s an effective interim solution:

Painting a shower floor surface with a layer of HydroBan or RedGard isn’t the most aesthetically pleasing solution, but it is cheap and effective. And it gives some time to figure out and save up for a truly permanent solution.

The Permanent Fix

The client understandably didn’t want to nuke everything to the studs for a completely new shower. And, since the previous installer had at least used concrete backerboard as a substrate for the shower wall tile, completely starting over wasn’t necessary. Instead, it was possible to just replace the shower base and curb and the first two rows of wall tile.

While it’s best to have a continuous waterproofing layer all the way up the shower walls, tile installed directly on concrete backerboard isn’t a major issue so long as there is effective waterproofing for the shower base and curb. So, just replacing the shower base is often all that’s needed to turn a super-leaky shower into a waterproof for 20 years shower. It’s not an inexpensive fix, but at least more economical than ripping out everything and starting over.

The Plan

Pretty straightforward:

  1. Carefully remove the existing semi-frameless glass partition and door for re-install
  2. Demo the exiting shower floor tile, curb, and base down to the plywood subfloor
  3. Remove the first two rows of wall tile
  4. Re-plumb the shower for a new Kerdi drain and install a new curb and properly sloped concrete base for the shower floor
  5. Install Kerdi fabric waterproofing for the shower floor and RedGard paint-on waterproofing for the exposed shower wall substrate
  6. Install new tile and grout for the shower floor, curb, and walls
  7. Re-install the semi-frameless glass partition and door

A fix plan that’d be less invasive (and therefore a bit less expensive) than replacing the entire shower.

The Demo

Very straightforward, and very revealing. The shower base was constructed from 1/4-in concrete backerboard nailed to the plywood subfloor (not necessary), a ~3/4-in layer of concrete to form the shower floor slope (wrong kind of concrete, but at least effectively sloped), and then the shower floor tile and grout:

What’s missing here? Waterproofing. Of any kind.

While I’d previously seen leaky showers constructed with bizarre waterproofing and leaky showers constructed with improper waterproofing, this was one of the few times I had seen a ‘custom’ tile shower installed with literally no waterproofing at all.

Sometimes you can give a previous contractor (or DIY reno-flipper) charitable benefit of the doubt and assume that at least they were trying to do something in the (wrongly) right way. Not so in this case. Unfortunately for this new homeowner, this was pretty clearly a case of just straight-up crooked misrepresentation. Not even the dopiest shower installer would make the ‘honest’ mistake of not waterproofing a shower base at all.

The Plumbing and Waterproofing

The only silver lining was that fixing the problem would be completely straightforward. First step was to re-do the drain plumbing for installing a Kerdi drain — which was needed anyway, since the previous dopey contractor hadn’t even bothered to repair the subfloor framing at all after doing their own plumbing “fix” to convert the previous tub into a shower:


The only thing that’d been previously covering this big rectangular hole in the subfloor was a single piece of 1/4-in backerboard. Not good.

In contrast, here’s what the properly patched subfloor looked like:


Underneath the new plywood is two lengths of 2×6 screwed onto the existing floor joists with doubled 2x4s run between to support the subfloor patch. This brought the carpentry back up to code.

Putting in the drypack concrete to form the shower floor slope looked like this:

And finally, the shower floor got Kerdi fabric for waterproofing and the shower walls and curb got a wrapping of Kerdi fabric with RedGard paint-on waterproofing above that:

Ideally you’d want to use RedGard all the way up the tile walls to make a continuous waterproofing barrier underneath all the shower tile. But tile directly on top of concrete backerboard for the shower walls isn’t terrible. In order to last a couple decades, a shower just absolutely needs continuous waterproofing for the floor and curb and extending up the floor/wall joints to the curb height.

The Tile Install

Re-installing the new matching wall tile and the new shower floor tile was easy-peasy.

The only challenging part was re-building the shower curb to the exact height of the previous curb, so that the semi-frameless glass door and partition could be re-installed to the exact previous dimensions.

The Glass Re-Install and Finish!

Luckily, this wasn’t my first rodeo with re-installing glass shower doors and partitions.

Now with proper waterproofing, the shower will be good for a couple decades at least. And, by replacing just the shower base instead of the whole thing, the client got a permanent fix for a little over half of what nuking everything to the studs would have cost.

Yay fixes!