Waterproofing under tile — the liquid membrane system — is the invisible layer that protects the structure from water, under a shower, a terrace or a pool. It is applied to a sound substrate before laying the surface, with reinforcement bands at corners and junctions. It's the item you never economise on: failed waterproofing only shows once the damage is done.
- Where
- Showers, terraces, pools, balconies
- What
- Liquid waterproofing membrane
- Key points
- Bands at corners and junctions
- When
- After the substrate, before the tile
- Stakes
- Prevent any structural leak
Where waterproofing is essential
Anywhere water pools or runs on a structure: shower floor and walls, walk-in tray, pool surround and basin, terraces and balconies above living space. Tile and grout are not waterproof on their own: it's the layer beneath that truly protects the slab and the rooms below.
- 01
Prepare the substrate
The substrate must be sound, clean, dry and flat. We fill, sand down high points and dust off: the membrane only bonds well to an impeccable substrate.
- 02
Priming coat
Application of a primer suited to the substrate to guarantee the membrane's adhesion and block absorption.
- 03
Reinforcement bands
Waterproofing bands at internal corners, floor/wall junctions and around drains — these are the points where water infiltrates first.
- 04
Membrane application
Two cross-applied coats of the liquid membrane, respecting drying times between coats, to full and even coverage.
- 05
Check and flood test
For a pool or shower, a flood test validates the work before the tile is laid.
No. Cement grout is microporous and eventually lets moisture through. Only continuous waterproofing beneath the surface truly protects the structure.
