How Much Tanking Do I Need for a Shower? (UK)
Tiles and grout are not waterproof, so a shower or wet room needs tanking behind them. A 1.2 × 0.9 m alcove shower tanked 2 m high is 7.1 m² (1.08 m² of floor and 6.00 m² of wall). At the 1 kg per m² stated for two coats of Mapei AquaDefense, with 10% extra, that is 7.8 kg, or 2 tubs of 7.5 kg, and 8 m of tape for the corners. The tanking calculator does it for your shower.
Quantities by shower size
Alcove shower, three walls tanked 2 m high, 10% extra, 1 kg per m², 7.5 kg tubs:
| Shower | Area | Tanking | Tubs | Tape |
|---|---|---|---|---|
| 0.8 × 0.8 m | 5.4 m² | 6.0 kg | 1 | 8 m |
| 0.9 × 0.9 m | 6.2 m² | 6.8 kg | 1 | 8 m |
| 1.2 × 0.8 m | 6.6 m² | 7.2 kg | 1 | 8 m |
| 1.2 × 0.9 m | 7.1 m² | 7.8 kg | 2 | 8 m |
| 1.5 × 0.9 m | 7.9 m² | 8.7 kg | 2 | 9 m |
Quantities by wall height
For a 1.2 × 0.9 m alcove:
| Height | Area | Tanking | Tubs |
|---|---|---|---|
| 1.8 m | 6.5 m² | 7.1 kg | 1 |
| 2 m | 7.1 m² | 7.8 kg | 2 |
| 2.2 m | 7.7 m² | 8.4 kg | 2 |
| 2.4 m | 8.3 m² | 9.1 kg | 2 |
A wet room
A 2 × 1.5 m wet room with all four walls tanked 2 m high is 17.0 m² and 18.7 kg of tanking. A wet room needs a sloped floor and a drain system built for it, which is a bigger job than these figures cover.
Applying it
- Prime the boards if the maker asks, and fill any gaps and screw heads first.
- Press the tape into the first coat at every corner, the floor-to-wall joint and around the drain and pipes, then cover it with the second coat.
- Apply each coat to an even thickness and let the first dry before the second.
- Leave it to dry for the time stated before tiling, and use the adhesive the maker names.
- Tank niches, benches and the shower tray surround as well as the walls.
Plan the tiles with the tile layout calculator and count them with the tile calculator. Coverage figures vary with the product: the instructions on the tub and the building regulations rule.
Frequently asked questions
How much tanking do I need for a shower?
Add the floor and the walls, then multiply by the coverage of the product. A 1.2 × 0.9 m shower tanked 2 m high is 7.1 m², which is 7.8 kg of liquid tanking at 1 kg per m² for two coats, with 10% extra: 2 tubs of 7.5 kg.
How many coats of tanking do I need?
Two coats is usual for liquid tanking. Follow the instructions on your product.
How high should I tank a shower?
Cover the whole wet area, which in a shower is usually the full wall height or as high as the spray reaches. The product instructions give the maker's requirement.
Do I tank the floor as well?
Yes, and use tape at the floor-to-wall joint and the corners. That is where leaks start.
More guides
Tools & materials for this project
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Estimates only. Quantities depend on your materials, site and supplier. Confirm important numbers before you order, and check the Building Regulations and any planning rules for anything structural or close to a boundary.
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