How to Make a Wet Room

Modern wet room with shower tower and shower screen

Let’s take you through what you need to know in order to make a wet room, including how to prepare the space and how to tank and tile your wetroom so that it remains waterproof. If you are experienced at DIY then you may feel confident enough to take this task on, but if not then we highly recommend to call in a professional.


A wet room will only ever be as waterproof as the surface that’s used to line it. The surface, whether that may be tiles, tile backer boards, liquid rubber membranes, or some other type of waterproof covering, will not remain waterproof if the surface it’s stuck to is not completely sound.

  • The first step to creating a wet room is to ensure the floor is not loose and the walls are not prone to excessive movement, and do not have a flaky surface. All surfaces need to be free from dirt and grime.
  • When constructing a wet room, the tiles are more for form than function as there’s too much water to depend on just the tile grout for a totally waterproof area for very long.
  • Gravity makes all the water head downwards, and if the wet room floor is not properly prepared and treated it will inevitably lead to problems.
  • Decide if your wet room will be completely open plan, or if you would prefer to fit a wet room glass screen.
  • Make sure to follow our step-by-step guide on how to make a wet room waterproof.
wet room with black shower tower

Making a wetroom on a concrete floor

  • The hardest thing about creating a wet room floor on a concrete base is fitting the drain pipe that takes the waste water away. This is usually achieved by using a concrete breaker to dig a channel through the floor, with a large hole at the point where the waste outlet will be positioned.
  • The floor grid or outlet plate sits on top of the tanking and directs the water into the trap. If any water seeps under the grid it will go directly into the trap.
  • The drains should be laid in accordance with Building Regulations and if there’s any alterations to existing drain runs or access chambers and manholes, they need to be reported to the Building Control Department of your local council.
  • The channel that houses the drain is concreted over and a fall is formed into the floor by using a self-levelling floor compound that’s thickened slightly with sharp sand.
  • You don’t need to create a steep slope – water will find its way to the lowest level. A 10mm fall over 2m is sufficient.
  • The floor plate is positioned so the pipe goes down into the trap.
  • The tanking is applied over the plate as are the tiles, and a grid is then fitted into the top of the floor plate.

Making a wetroom on a timber floor

  • To create a wet room on a timber floor you’ll need to take up the existing floorboards.
  • The lowest part of the floor needs to be chosen and then the joists surrounding the low point will need to be raised up a little by using strips of timber known as firring pieces.
  • Ensure the joists are completely solid (if needed, strengthening timbers can be placed in-between the joists). The plywood (a 25mm thickness is recommended) must be screwed down to the joists and strengthening timbers at a minimum of 300mm centres.
  • The screw heads should be countersunk under the surface of the plywood, so the tanking, that’s glued to the plywood, cannot be pierced.
  • The drain pipe needs to run between the joists.
  • The pipework can then be put through the wall to run into an existing soil and vent pipe.
  • Once tanked, you can then tile over the tanking to complete the wetroom.
  • Use a flexible adhesive and waterproof grout to complete the tiling paying attention to the joints.

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