A bathroom is waterproofed before it is tiled — the barrier goes under the finishes, on the floor and up the wet walls. Done during construction it is a modest task; done after tiles are on, it means reopening the room. That asymmetry is the whole strategy: get it right the first time.
What gets treated in a new bathroom
- The whole floor, treated as a tray — the barrier turned up every wall base so the floor can hold an accidental pool without passing it downstairs.
- Wet walls to height: the shower and tap walls well above shower head level; other walls at least through the splash zone.
- The floor–wall junction: the right angle that moves and leaks; coved and reinforced, never just painted across.
- Around every penetration: the drain, the traps, each pipe through floor or wall — collared individually. Leaks live at holes, not in open floor.
- The door threshold: the barrier returns at the doorway so water cannot wick into the bedroom floor.
Chemistry: this is the natural home of cementitious and polymer-modified systems, which bond well and live happily under tile adhesive — the family logic is in the types guide.
The order of work
- Plumbing complete and pressure-tested — before the barrier, not after.
- Surface sound, clean, cured.
- Junctions and penetrations detailed first, then the field coats.
- Cure fully, then flood-test the tray for a day and check the ceiling below.
- Only after a dry test: tile.
The existing bathroom that leaks
A stain on the ceiling below the bathroom means water is escaping the tray — but from where is the real question: a failed pipe joint, a perished junction, or grout lines feeding a floor with no barrier at all. Chasing it with surface sealers rarely ends it. Diagnosis comes first — leak reasoning applies — and honest options range from re-grouting and junction repair up to reopening the floor. Photographs of the stain and the bathroom above via the waterproofing page get you a straight assessment of which.
Frequently asked questions
Can tiles themselves be the waterproofing?
No — tiles and grout shed water but pass it at every hairline. The barrier is beneath them or it does not exist.
Does a first-floor bathroom need it if the ground floor is mine too?
Yes. The slab, the plaster and the wiring below are yours as well; the barrier protects the building, not just the neighbour.
How long before tiling can happen?
After the system's full cure and a passed flood test — the product's own specification governs the days.