When we demo an existing shower — whether for a full bathroom remodel or a retile — we almost always see the same failure modes. Cracked grout, loose tile, mold in the walls, soft substrate. The cause is almost never the tile itself. It is what happened underneath, before the first tile went up.
Here are the six most common failure modes we encounter in Central Florida showers, what we see when we open them up, and what we do differently.
1. No Real Waterproofing System
What we see
Cement board screwed to studs, with tile set directly over it. Cement board is not waterproof — it is water-resistant. It holds up when it gets wet, but it is not intended to serve as a waterproof barrier. Water gets through the grout joints over time, saturates the cement board, and eventually reaches the framing. In Central Florida's humidity, that process accelerates.
Why it fails
Grout is not waterproof. No matter how well sealed, grout allows some moisture transmission over years of use. A shower needs a dedicated waterproof plane between the tile and the framing — either an applied membrane (like Schluter KERDI), a foam panel system (like GoBoard), or a liquid membrane. Cement board alone is not that plane.
What we do
Every shower we install gets a named waterproofing system — GoBoard panels or Schluter KERDI membrane — specified in writing in the estimate. We do not use cement board as the sole backing on shower walls.
2. Failed Pan or Drain Detail
What we see
A shower pan that was never properly waterproofed at the drain connection, or where the liner was torn during installation and never repaired. Water gets under the tile and sits in the mud bed. Eventually the mud bed saturates, the tile delaminates, and the subfloor underneath begins to fail.
Why it fails
The drain is the most vulnerable point in any shower floor. The connection between the waterproofing membrane and the drain body must be fully bonded. A gap at the drain — even a small one — allows water to migrate under the entire floor.
What we do
We use either a pre-sloped foam pan with manufacturer-specified drain integration, or a Schluter KERDI-DRAIN which bonds directly to the KERDI membrane. The drain detail is inspected and confirmed before any floor tile is set. On foam pan installations, the slope is built into the pan — no guessing on the mud bed.
3. Substrate Movement
What we see
Backer board that was not properly fastened — too few screws, wrong screw spacing, or screws at the wrong locations — allows the substrate to flex under foot traffic and thermal movement. The tile bond breaks at the thinset, grout joints crack, and water penetrates.
Why it fails
Tile is rigid. A substrate that moves, even slightly, will eventually crack the grout joints or pop individual tiles. Proper fastening of backer board is not just about holding the panel in place — it is about eliminating any flex between the panel surface and the framing behind it.
What we do
We follow manufacturer fastening schedules for every substrate product we use, and we verify the wall framing is solid before boarding begins. If we find movement in the existing framing — not uncommon in older Central Florida homes — we address it before the new substrate goes up.
4. Wrong Thinset for the Tile and Substrate Combination
What we see
Tile that pops off cleanly when demoed — sometimes with very little force — because the thinset never bonded properly. Either the wrong product was used, the coverage was insufficient, or the tile was placed after the thinset had already begun to skin over.
Why it fails
Not all thinset is appropriate for all tile and substrate combinations. Large-format porcelain needs a medium-bed or large-format mortar that maintains coverage without slumping. Natural stone often requires a white, non-staining thinset. Schluter KERDI membrane requires unmodified thinset for the membrane layer. Using a standard polymer-modified thinset on KERDI is a documented failure mode.
What we do
We specify the thinset brand and type in writing for every installation. On large-format tile, we use medium-bed mortar and back-butter every piece. We verify coverage by lifting a tile periodically during installation — 95% coverage minimum on floor tile, 80% minimum on wall tile. For more on large-format specific requirements, see our post on large-format tile installation.
5. Inadequate Slope to Drain
What we see
Shower floors that hold standing water — sometimes only a quarter inch, sometimes several inches across the floor. Water that stands is water that finds its way through grout joints over time, and it also creates a slip hazard and a mold environment.
Why it fails
The minimum slope for a shower floor is 1/4 inch per foot toward the drain in all directions. On a mud-bed floor, achieving this slope consistently requires skill and the right tools. Builders who rush this step end up with low spots that hold water. On pre-sloped foam pans, the slope is engineered into the product — which is one reason we use them on clean rectangular layouts.
What we do
Every shower floor we install is checked for slope before tile is set. On custom mud-bed floors, we set screed guides at the correct elevation and verify the slope with a level. On foam pan installations, the product provides the slope — and we verify the drain sits at the correct elevation relative to the finished floor.
6. Unsealed Penetrations
What we see
Water damage originating at the mixing valve rough-in, at recessed niches where the waterproofing was not continued, or at inside corners where the membrane was not properly reinforced with band material. These are the points where the continuous waterproof plane is most likely to be interrupted.
Why it fails
A waterproofing system is only as strong as its weakest point. A membrane that is perfect across 90% of a shower and missing at the mixing valve penetration will allow water to migrate through that gap into the framing behind. Over years of daily use, that adds up to significant structural damage.
What we do
Every penetration through the waterproofing plane gets addressed before tile is set. Mixing valve rough-ins are sealed at the membrane. Inside corners get KERDI-BAND (on KERDI systems) or GoBoard joint tape set in adhesive. Niches are waterproofed on all five surfaces, not just the visible face. We do not tile over an unsealed penetration.
The Common Thread
Every failure mode above comes down to the same thing: steps skipped before the tile went up, where the problem would not be visible until it had already caused damage. The tile looks fine at first. The failure is invisible until the grout cracks, the tile loosens, or someone opens the wall and finds wet framing.
Hiring a tile contractor who can explain exactly what waterproofing system they use and why, specify it in writing, and stand behind the installation is the most direct way to avoid ending up with a shower that needs to be ripped out and redone.
If you are planning a new shower installation or a bathroom remodel in the Sanford, Lake Mary, or Heathrow area, reach out for a written estimate. We have 15+ years of tile experience and our waterproofing system is always specified in writing.