How to Fix a Shower Floor Slope

This post describes how to fix a shower floor slope without having to rip everything out to start over from scratch. If the shower is properly waterproofed, then it can be possible to carefully re-tile just the shower floor to eliminate dead spots that don’t drain properly.

Bad Tile Install
Uneven wall tiles and jagged grout lines, plus dead spots on the shower floor.

Badly done shower floor tile is a real drag. These folks spent a lot of cash to convert a half bath on slab foundation to a full bath. Fifteen grand and a couple months of headache, but at least they had a cool retro 1940s -style full bath at the end. Technically.

Unfortunately, the tile finish wasn’t great and the shower floor had multiple standing water dead spots. It’s no fun when your shower floor has low patches that don’t actually drain down the drain. That’s a recipe for fast short-term surface bacteria and mold growth. Plus it’s just no fun to end each shower standing, cold and dripping, kicking puddles at the drain.

The (main) Problem

Cosmetically, the subway tile on the shower walls was also installed wonkily with unfortunate lippage. You really don’t want to see shadows cast by the tile on grout seams.

But most annoyingly for function, the shower floor wasn’t properly sloped to the drain. Meaning, it didn’t drain. Dead spots in three of the four corners pooled water with every use, making for surface mold growth and a persistent damp smell.

The Options?

The conventional option would be to nuke the entire shower and start over. But, that would be a super drag. Just bought yourself a custom shower and frameless glass enclosure for $6k or more? Great! Now, immediately demo ALL of it to start over from scratch? Not great.

An alternative option would be to simply install new tile right on top of the existing shower floor tile. While this might seem like a wacky idea at first, it’s actually often the most effective and least expensive way to fix a bad floor in an otherwise watertight shower. This post details the entire process.

Another option would be to carve into the shower to remove just the floor tile and re-slope the shower base without demolishing anything else. This would normally be a pretty risky approach, since you generally can’t know in advance just how (or how effectively) the previous installer waterproofed a shower base. For example, if there’s a vinyl PVC liner with just a thin layer of deck mud concrete lurking below, then chiseling into the shower floor surface tile is likely to puncture the liner and result in having to demo the whole shower and start over.

In this case, the clients knew firsthand that there was a nice thick fiberglass waterproofing liner under a pretty thick concrete layer below the shower floor tile. They had watched (and smelled) the fiberglass installation process firsthand.

So, this meant it’d likely be possible to remove just the shower floor tile, re-slope the floor, and then re-tile it without disturbing the waterproofing layer underneath. Not a 1,000% guarantee, but pretty close since this is something that I’ve done multiple times with so far perfect long term results. This was therefore a great opportunity to fix a shower floor slope for a fraction of the cost of replacing the entire shower.

The clients agreed that it was worth the risk to try. I would’ve too.

The Shower Floor Slope Fix Plan

The dead spots in the shower floor were both the main annoyance and the main long-term problem. So, with a shower base waterproofing barrier at least doing it’s job of waterproofing the shower base, this was the plan for a minimally invasive fix:

  1. Gently remove all of the shower floor tile
  2. Re-slope the shower floor using a dense thinset mix
  3. Re-tile and re-grout the shower floor
  4. Do an overnight flood test to ensure no damage to the fiberglass waterproofing pan

Seems easy? In theory, yes. In practice tho, effectively re-sloping a shower floor base with a skimcoat of thinset is actually kinda difficult. And, fitting new hexagonal mosaic floor tile dead even to an existing footprint is also a challenge. Normally, you’d be able to cover the edges with the wall tile install. In this case, the clients chose to make the perimeter grout a feature.

The Shower Floor Slope Fix Result!

Both re-sloping with a thinset layer and the re-tile install actually went exactly to plan. The clients chose to reinstall the same mosaic floor tile and pattern, but chose to use a medium-grey grout color that made for a very nicely unique framing border along the edges.

The finish was a shower floor that now drains properly from every corner. And the most important result? Very happy clients. You can see the Yelp review here:

Alicia S.‘s review of Art Tile & Renovation