Wet-rooms can be designed to fit small or large spaces and often provide a simpler and more practical solution than trying to accommodate a conventional shower or bathroom in a small area. This post looks at 4 tips to consider when installing the wetroom.
Positioning waste 
Ready to Use
Tip 1/ Get the floor right from the start!!
The slope in the floor is the required angle or drop in the floor that runs from the edges of the designated wet area to the waste outlet. The minimum recommended fall is 15mm and the maximum recommended ratio is 85:1, (i.e. for every 85mm the incline travels towards the waste outlet the floor level will fall 1mm.)
It is imperative that the slope/fall is formed into the wetroom floor itself. The floor must never be flat, and you should never try to create the falls with tiling.
The easiest way to create this slope, or fall, is to use a Shower Tray Former. These can either be bought in stock sizes with set waste positions or alternatively bespoke formers can be made to your exact specifications. The Shower Tray Former can be installed onto a wooden deck or a concrete floor. Most of these products can be cut to fit an exact requirement.
If not using a Shower Former, the fall in the floor can be created by using noggins or spacers on top of the floor joists to create a gradient, and then placing the marine plywood on top of these as would normally be the case in the new bathroom installation.
Tip 2/ Make sure you’re on solid ground!!
It is important that the bathroom or wetroom floor is rigid and stable prior to tanking & tiling. Obviously, on a concrete floor this is not an issue, but in a typical Irish house with the main bathroom on the first floor, the wooden joists will need to be stabilised in the immediate shower area and possibly throughout the entire bathroom. This is done by constructing a sub floor within the joist space using strong marine plywood. Using extra noggins to support existing beams is normally the method used, and also it’s worth remembering that it is important to support the waste/outlet underneath the wet area or shower former.
The minimum recommended thickness of the flooring to be laid on top of the joists is 20mm as recommended in Building Regulations.
Tip 3/ Make sure the water can drain away!!
The wet-room drain (waste outlet) should be a top accessed, trapped unit with a constant flow rate in excess of the output of the shower running at full capacity. Wetroom drains are typically either linear drain or shower gully. Either type of drain can be used directly onto marine ply, and waterproofed accordingly, or both types are also available and can be incorporated into a pre-formed Shower Former. The customer normally decides what style of drain they would like to use, as the aesthetics and capabilities of both are completely different. Some customers do prefer having the Shower Former as extra waterproof ‘security’, but once the job is done correctly by an experienced installer, both methods will be successful.
The position of floor joists, and the direction in which the joists are running, will need to be looked at when deciding on waste type, as will the direction, height and position of where the waste pipes will exit the bathroom and join existing waste and soil pipes.
Water usage is vital to consider as discussed previously. All drains have max. flow rates, so it is important to know the max. amount of water in use, and the water evacuation capacity of the drain under consideration.
Tip 4/ Don’t put up with leaks!!
All wet-rooms must be tanked. Unless the designated shower area is to be completely isolated within the bathroom by partitions, then the minimum requirement for waterproofing a wet-room is to do the entire floor area, turn up the walls a minimum 100mm and floor to ceiling to the walls in the immediate shower area.
If the area is isolated then the waterproofing can be restricted to that area, but should extend beyond it by a minimum 300mm.
The waterproofing system must follow the contours of the slope to falls (hence the reason why the incline must be formed into the floor) and be dressed into the waste unit to seal it.
Next month we will look in further detail at the types of drains, and after that we will look in some detail at types and methods of waterproofing.
Niall Byrne, niall@livingspaces.ie
Unit 713, Northwest Business Park, Ballycoolin, D15, D15AE39.
March 2021.
Ack. – Koster Aquatechnic Limited.