Service
Wet room and shower tiling, with tanking
Tanking a shower or wet room before tiling costs £100 to £250 depending on the area, in MyJobQuote's 2026 floor tiling guide, with tiling labour on top at £20 to £50 per m² across the MyJobQuote and Checkatrade guides. Tiles and grout are not waterproof: the tanking behind them is what keeps water out of the walls.
What this covers
What it costs. Waterproofing a wet area before tiling costs £100 to £250, depending on its size, in MyJobQuote's floor tiling cost guide (July 2026). Full cost breakdown.
Typical jobs
- Tanking and tiling a level-access wet room with a linear drain
- A walk-in shower on a sloped former, tanked wall to floor
- Strip and re-tile of a leaking shower, with new tanking behind
- Waterproof backer boards and taped joints in a new shower enclosure
- Small-format floor tiles laid to the fall of a wet room floor
What is involved
In a wet room the whole floor is the shower tray. Water runs across the tiles to a drain, so the floor is built to a fall, usually on a pre-formed sloping board or a sand and cement bed laid to the gradient, and the tiles follow that slope. Small tiles bend to a fall more easily than large ones; large tiles can be used with a linear drain, which lets the floor slope one way only. The walls and floor are tanked as one continuous waterproof layer before any tile goes down.
Tanking means a liquid membrane painted on in layers, a sheet membrane bonded to the wall, or waterproof backer boards with every joint and screw head sealed. Whichever is used, the weak points are the same: internal corners, where the wall meets the floor, pipe entries and the drain. Each gets a reinforcing tape, collar or pre-formed corner from the same system, and the drain must be one designed to clamp the membrane. BS 5385-4 is the part of the British Standard covering tiling in wet conditions, and tanking makers publish their own instructions; a tiler should follow one system from end to end rather than mix products.
When a tiled shower leaks, the cause is usually behind or around the tiles: failed tanking, a tray seal, a pipe joint or the silicone, not the tiles themselves. The leak shows up months later as a stain on a ceiling below or a soft floor. That is why it is worth asking for photographs of the tanking before it is tiled over, and a note of the product and its batch. Many tanking makers require a flood test or a curing time before tiling; ask whether your tiler does one. Grout and silicone in a wet room are maintenance items, not the waterproofing.
Choosing someone for the job
In a wet room the tanking and the floor fall do the work, and both are hidden by the end of the job.
- Which tanking system will you use, and is it one maker's from wall to drain?
- How are the corners, pipe entries and the drain treated?
- Will you photograph the tanking and note the product and batch before tiling?
- How is the fall formed, and who supplies the drain?
- Do you flood test or wait out a curing time, and what floor tile size do you suggest?
Read next
Common questions
Are tiles and grout waterproof?
No. Glazed tiles shed water, but grout is porous and hairline cracks open over time, so water reaches the wall or floor behind. That is why showers and wet rooms are tanked first, as BS 5385-4 sets out.
What is tanking?
A waterproof layer behind the tiles: a liquid membrane painted on, a sheet membrane, or waterproof boards with sealed joints. It covers the walls and floor of the wet area as one continuous layer, with tapes and collars at corners and pipes.
Do I need to tank a shower enclosure as well as a wet room?
Yes, the walls inside the enclosure at least. An enclosure keeps water off the room, but the tiled walls inside it are soaked every day.
How long after tanking can you tile?
It depends on the system. Liquid membranes need each layer to dry, often a few hours each, and some makers ask for a day before tiling. Sheet membranes and sealed boards can be tiled sooner. The maker's instructions set the time.