Inspirations/Detail
Detail · 8 min read
Waterproofing is the only bathroom decision you cannot revisit
Everything else in a bathroom can be changed later. This cannot.
Taps can be swapped. Tiles can be redone, expensively. But waterproofing sits under the screed, under the tiles, behind the finished surface, and reaching it means demolishing everything above. It is the one line in a bathroom quotation that deserves your full attention, and it is the line most often thinned to win the job.
What a competent job looks like: the membrane goes over the slab and turns up the wall at least 300mm, higher in the shower zone — 1,800mm is the sensible number. All corners and pipe penetrations are treated separately before the general coat. Then the floor is flooded and held for 24 hours and checked from the ceiling below before a single tile is laid.
That flood test is your leverage. Ask for it in writing, ask to be there, and photograph it. A contractor who resists it is telling you something useful.
Slopes matter as much as the membrane. A bathroom floor should fall roughly 1 in 80 towards the drain, with no flat spot and no counter-fall behind the door. Water that stands is water looking for a way through.
Slopes matter as much as the membrane.
