Just about every month, I get calls from folks with the same problem. Their tile 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. Sometimes their newly done upstairs shower literally drips water into the room below. This post describes how you can fix a leaking shower pan without having to completely rip out everything to start over.
This post is part of my shower repair series. Most all custom tile shower installers will say that nuking everything and starting over is the only way to fix a leaking shower pan. This is because it’s the easiest, most straightforward, and most expensive fix. It’s the capitalist thing to do. As a socialist marxist myself, I like to offer lower cost options whenever possible.
The Situation
The clients had just bought a newly-renovated house-turned-duplex in the Hyde Park neighborhood of Austin. They bought it 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 tile showers can look okay 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.
Here’s the thing about tile and grout. TILE AND GROUT ISN’T WATERPROOF! There is no wonderseal solution to this. That’s why tile showers need a “shower pan” layer of waterproofing underneath the surface tile and grout.
The Temp Fix
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. It’s ass backwards to put the waterproofing layer on top of the surface tile. But it will keep your shower from leaking into the walls and floor below until you can schedule a permanent fix.
The Permanent Fix
The client understandably didn’t want to nuke everything to the studs to fix their leaking 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 can fix a leaking shower. It’s not an inexpensive fix, but is more economical than ripping out everything and starting over especially if it means you can re-use existing frameless glass.
The Plan
Pretty straightforward:
- Carefully remove the existing semi-frameless glass partition and door for re-install
- Demo the exiting shower floor tile, curb, and base down to the plywood subfloor
- Remove the first two rows of wall tile
- Re-plumb the shower for a new Kerdi drain and install a new curb and properly sloped concrete base for the shower floor
- Install Kerdi fabric waterproofing for the shower floor and RedGard paint-on waterproofing for the exposed shower wall substrate
- Install new tile and grout for the shower floor, curb, and walls
- Re-install the semi-frameless glass partition and door
This is a fix that’s again a bit less expensive than replacing the entire shower. It’s still a lot of work, but it saves on materials and the labor cost of tiling three walls. It can also save the 1,5-2k cost of new frameless glass.
The Demo
The shower base on this install 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 sloped), and then the shower floor tile and grout:
What’s missing here? Waterproofing of any kind! While I’d previously seen leanking shower pans constructed with bizarre waterproofing and leaky shower pans 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 this leaking shower pan would be completely straightforward. First step was to re-do the drain plumbing to install a Kerdi drain flange, 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. Also, the 2-in shower drain was piped to a 1-1/2 inch pipe. Again, not good. Here’s what the not pretty but properly replumbed and 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. The shower drain was also now connected to 2-in drain pipe, which brought the plumbing 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. This is my preferred method for waterproofing a tile shower.
Like the Millenium Falcon, this shower base waterproofing might not look pretty but has it where it counts. The floor and floor/wall joints and curb are all wrapped with Kerdi waterproofing. And every seam is extra sealed with “KerdiFix” sealant for good measure. And, for triple measure, we put a generous layer of RedGard on top of 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 for decades, a tile shower just needs a continuous waterproofing pan for the floor and curb.
The Tile Install
Re-installing the new matching wall tile and the new shower floor tile was easy-peasy.
The most challenging aspect to this fix for a leaking shower pan was re-building the new shower curb to the exact height of the previous curb.
The Glass Re-Install and Finish!
You need to rebuild the curb to the EXACT original height for reinstalling shower glass. If you don’t get the new dimensions right to +/- 1/16th of an inch, you can’t re-use the origional glass. Luckily, this wasn’t my first rodeo with re-installing glass shower doors and partitions.
This is how you can fix a leaking shower pan. With a properly waterproofed base, the tile shower will be good for a couple decades at least. And, by fixing just the leaking shower pan base instead of the whole thing, the client got a permanent solution for half of what nuking everything to the studs would have cost. Yay fixes!
