The situation
Illustrative example. Not a real job or customer.
In a single-story Fullerton house on a slab, the primary bathroom has a tiled stall shower. The painted baseboard on the outside of the shower curb has started to swell and the grout along the bottom row of floor tile stays dark long after showers.
- The meter test shows no movement with everything off, so a pressurized supply leak is unlikely.
- Running water only on the wall tile for ten minutes, keeping the floor as dry as possible, causes no new damp.
- Pouring water straight into the drain causes no new damp.
- A flood test with the drain plugged shows the water line dropping slowly over several hours, and the baseboard darkens.
With the walls and drain ruled out, the evidence points to the shower pan or liner under the tile.
How a rebuild could unfold
- Before work
- Written scope, tile plan and permit question settled with the city.
- Demolition
- Floor tile, mortar bed and the failed liner are removed; the curb and lower walls are opened as needed.
- Inspection of damage
- Subfloor, framing and slab edge are checked and allowed to dry.
- New waterproofing
- A new liner or waterproofing system is installed, sloped to the drain and flood tested before tile.
- Finish
- Mortar bed, tile and grout go back, and the baseboard is replaced.
Why the order of tests mattered
A failed pan means removing the shower floor, so it should be the conclusion after other causes are ruled out, not the first guess. Each earlier test was quick and cheap and removed one possible cause from the list.
Had the wall test produced damp, regrouting and recaulking might have solved the problem without touching the floor.
Lessons from the example
- Dark grout at the floor line that never dries is an early warning
- Test walls, drain and floor separately
- A flood test needs hours, not minutes
- Get the rebuild scope, including tile, in writing
- Ask whether a pan inspection is required
Common questions
Is this a real case?
No. It is an invented example.
Could a coating have fixed it?
Surface coatings are sometimes offered. Ask how they work with a failed liner underneath and how long they are expected to hold.
Does a slab make it worse?
Water can soak into the slab edge and flooring rather than dripping somewhere visible, which can let damage spread longer.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.