ᐅ Adding a Shower Afterwards (Laundry Room)

My issue: Since my laundry room is fairly large, I installed a sauna and would now like to add a shower next to it. I have already tiled the existing wall sections (which are located at ground level/on a slope) but have not yet applied grout. Originally, I planned to build a wall to create an open wet room, which I could close off at the front with a shower curtain. However, I’m now unsure about this because I’m concerned that I might have missed applying a waterproof membrane to prevent water from penetrating the walls during shower use, which could lead to damp walls and mold. Is there some kind of sealant that can be applied over the tiles? How much slope should there be from the shower tray to the drain? (Concrete blocks for building a raised base are available.) Or is building up with concrete blocks on a slab floor not recommended?
Could someone please give me some advice?
Thank you very much in advance
mum

Hello mum,

You can install the shower as planned; to address the forgotten waterproofing, simply tile over the shower area from the inside again. However, don’t forget the waterproofing system ("liquid membrane"/brush-on waterproofing and flexible grout).

I would build the two side walls of the shower using drywall construction; metal studs with gypsum fiber boards. This allows for more precise work, is faster, and is especially more stable for the desired result.
The metal studs and connection profiles are screwed to the floor, ceiling, and wall, providing sufficient resistance against horizontal forces.
This is not as easy with masonry walls. A masonry wall without interlocking or embedding into the floor/ceiling/adjacent wall is not stable against horizontal forces and could collapse under enough lateral pressure.
This can be managed with wall ties, for example, but by the time you have drilled the holes and installed the anchors at the correct height, the stud wall will already be finished.
Tiles should be installed using a thick-bed method (or the side walls plastered); tiles can be glued directly onto the gypsum fiber board, which is faster and more precise.

For the shower drain slope: it should be 2%. You can build the shower base as planned; that should not cause any problems.

Thank you very much

I just wanted to briefly thank you for the detailed response and also ask what the material is called that is placed under the bathtub for stabilization.

Since I only need to build one wall because I want to position the shower in the corner – meaning there are already two existing walls (which I have tiled) – I think I will choose a prefabricated corner shower and install it on a base.

I am now looking for a round shower enclosure, preferably without massage jets or special features – something simple.

Can anyone provide information on where I can find something like this?

Thank you, mum-1

Hello mum,
You can stabilize the shower tray with stones or use available tray supports (I hope I understood you correctly—it’s about stabilizing the tray itself so that it sits level and securely).
There are also prefabricated bases for shower trays, featuring a smooth surface in common ceramic colors, often offered together with the respective trays; otherwise, the gap between the floor and the shower tray is filled with aerated concrete blocks (which are easy to work with) and then tiled.

There are several bathroom fixture suppliers online where you can view different models from various manufacturers and possibly place an order.