How to install a wet room

Video by Wickes. This guide draws on the "How to install a wet room" tutorial from the Wickes YouTube channel. Wickes is one of the UK’s best-known DIY and trade suppliers with a comprehensive bathroom range, and their installation walkthrough covers the key stages of a wet room build clearly and in proper sequence - which matters a great deal when the order of operations is this important.

1. Check that the subfloor can take the weight

A wet room adds a tanking layer, a mortar bed for the drain, and tiles - considerably heavier than a standard shower tray. Timber joist floors usually need strengthening with an additional layer of plywood (18 mm minimum, screwed at close centres) to reduce flex. Any movement in a tiled wet room floor will crack the grout and eventually the waterproofing.

Concrete floors are generally fine as-is, provided they are flat and level. Check for damp below before you start - a wet room over a damp concrete slab is asking for trouble.

2. Install the linear or point drain

Position the drain where water will naturally flow to it. A point drain typically sits in the centre or near the shower valve; a linear drain usually runs along one wall. The drain outlet needs to connect to the existing waste stack or an independent branch - check the route before you commit to a drain position.

Set the drain body in position and pack it temporarily so it sits at the correct finished floor height. The waterproofing will wrap around the drain flange later, so it needs to be accessible and the flange must be the type designed for tanking systems.

3. Apply the tanking membrane

This is the most important step. Tanking waterproofs the floor and walls to a height of at least 1.8 m behind the shower area, and fully across the floor. Use a purpose-made tanking kit: brush-applied liquid membrane or a bonded sheet system.

Apply a first coat across all surfaces, paying particular attention to the floor-to-wall junction. Press tanking tape into that corner joint while the first coat is still wet. Apply a second coat and let it cure fully. The drain flange gets tanked in too - the membrane bonds to the flange so that any water on the floor can only escape through the drain, not under it.

4. Create the floor fall towards the drain

Water needs a gradient of around 1:60 to 1:80 to drain reliably without pooling. On a timber floor, use a purpose-made sloped foam former (widely available in wet room kit form) which gives you the fall without a heavy mortar screed. On concrete, a sand-and-cement screed is fine - mix it dryish and compact it firmly to the slope you need.

Check the fall in every direction with a spirit level before the screed or former sets. Getting this stage wrong means standing in slowly-draining water every morning.

5. Tile the floor with a suitable adhesive

Use a flexible, rapid-set adhesive rated for wet areas and floors. Porcelain and ceramic tiles both work well; avoid stone tiles in a shower area unless you are confident about sealing them. Small tiles (under 300 mm) conform better to the floor fall than large-format tiles.

Butter the back of each tile as well as the floor (back-buttering) to ensure full contact. Check the fall as you work. Leave drainage gaps around the drain body so water can reach it.

6. Tile the walls

Tile the walls after the floor is set. Work from the bottom up, starting one tile height above the floor so you can cut the bottom row to fit neatly against the floor tiles. Use waterproof grout and leave the floor-to-wall joint unsealed - apply silicone sealant there instead once the grout is fully cured (silicone accommodates the slight movement between floor and wall that grout cannot).

7. Fit the shower valve and screen

A thermostatic bar valve or concealed valve both work well in a wet room. If fitting a concealed valve, make sure the valve body is accessible for servicing through the wall or from the other side. Wet rooms typically have a fixed glass screen or half-screen rather than a full enclosure - just enough to stop water hitting the rest of the room directly.

Seal the screen-to-tile joint and the wall-to-tile joints around the valve with sanitary silicone. Run the shower for a few minutes and watch for any sign of water getting behind the tiles at the valve or screen fixings.

8. Grout, seal, and test

Use a waterproof grout throughout. Once cured, wipe away any haze with a dry cloth. Run the shower for 15 minutes and watch the floor drain freely. Check around the drain body for any sign of movement or water getting below the tiles. Check the base of the walls for any dampness appearing where the tanking might be compromised.

That said - if everything drains cleanly and the walls stay dry, you’re done. A well-tanked wet room should not give you any trouble for decades.

When to call a handyman

Wet rooms are achievable as a DIY project for a confident tiler, but the tanking stage in particular rewards experience. Call Richard if you are unsure about the subfloor structure, if the drain position is awkward, or if you want the work done to a standard you are confident will not leak. The cost of getting tanking wrong is considerable - typically a complete strip-out and start again.