Signs your wet room is leaking, and what to do about it
Most wet room leaks give a warning before they show up as damage. Knowing what to look for buys time to fix the cause rather than the consequence.
How do you know if a wet room is leaking?
A wet room is likely leaking if grout darkens permanently and won't dry back, silicone develops black spotting within its first year, water pools rather than draining, or a ceiling or wall in an adjoining room shows a damp patch below or beside the wet room.
Early signs, before any visible damage
Persistent surface dampness that doesn't dry between uses, grout that stays a shade darker than the rest of the floor, and slow drainage are all early indicators. None of these confirm a membrane failure on their own, but together they justify getting the room looked at.
Signs the leak has reached the structure
A stain on a ceiling below the wet room, a musty smell in the room beneath, or skirting and flooring lifting in an adjoining room are signs water has already reached the structure. At this stage the priority is stopping use of the wet room until the source is found, not just treating the visible symptom.
What causes most wet room leaks
The recurring causes are partial tanking that never covered the whole floor, an unreinforced internal corner that has cracked with normal building movement, a pipe penetration that was never properly collared, or a flexing timber deck that has cracked the tile bed above it. Almost none of these are visible without lifting tiles.
What a remedial investigation involves
A proper investigation identifies the specific failure point rather than resealing visible symptoms and hoping. This usually means lifting tiles in the suspected area, inspecting the membrane directly, and testing adjoining sections rather than assuming the whole floor has failed.
In a tenement flat, coordinate with the downstairs neighbour early — tell them the moment you notice a problem, not after it's resolved.