Shower designs are becoming ever more sophisticated
There are different ways to waterproof and install a wet room but if it is being done in an existing house rather than in a new-build (where options are greater because floor levels can be built to suit the wet room) then the most common method is to raise the floor level with a concrete screed and then install a flush concealed former that will help to ensure that the tiled floor surface is the correct angle for good drainage. Wet room formers come in a range of standard sizes but can also be manufactured to any shape and size you desire.
Once the former is in place the whole room, floors and walls, needs to be waterproofed before the tiles are fixed in place. Making sure the room is completely water tight is the most essential part of installing any wet room and whilst porcelain or ceramic tiles with a waterproof grout may be waterproof enough for an enclosed shower tray and surround or for a shower over a bath, they are not considered adequate enough for a shower area without a tray or a surround.
So never skimp on the waterproofing step.
The best way to create a fully water tight area is to use a waterproofing product that creates a barrier between the tiles and the floor or walls. One way of doing this is to lay a waterproof membrane, which is glued to the surface in non-overlapping panels with the joins between the panels then sealed with waterproof tape. The disadvantage of this type of waterproofing is that there is the potential for leakage if the waterproof panels shift over time to expose the joints.
The other option is to apply a waterproofing chemical product (many of which are environmentally friendly mineral-based products) which eliminates any concern about water leaking through gaps as it is applied in a single, continuous coat using a roller or spreader to any type of surface. Different products are available depending on the absorbency of the underlying substrate.
Whatever type of waterproofing you choose it will then be necessary to apply waterproof tape to all the wall-floor joints and corners before the substrate is ready for laying the chosen natural stone, porcelain or ceramic tiles.
Any type of water resistant tiling is suitable for a wetroom but bear in mind that some of the very large porcelain tiles now available might be difficult to cut to the required angle in order to create the correct slope towards the drain. The smaller the tile the easier it is to create the correct gradient;also small tiles, with their proportionally larger areas of grouting, will usually be more slip-resistant than large porcelain tiles.
For this reason mosaic tiles or small ceramic tiles tend to be more popular for the showering area of the wet room. For the design-conscious, large porcelain tiles can be used in the main part of the room and on the walls with complementary mosaics in the shower area.
Use a flexible adhesive to ensure surface stability if there is any movement in the floor over time and an anti-fungicidal, waterproof grout to install the tiles and finally seal all wall-floor joints with a silicone sealant. Most adhesives and grouts are suitable for all types of ceramic tiles, porcelain tiles and natural stone but if you have some very delicate stone check with the supplier for advice as some delicate natural stones are susceptible to staining from certain types of adhesive and grout.