I've hit a bit of a snag in the "basement bathroom renovation" project. We think we've solved the floor (concrete), but we have walls with internal lightweight concrete elements. We were thinking of using microcement, and the instruction is to apply concrete filler (A46 or equivalent). I believe it's the same for tiles.
Some suggest you can also plaster, but it seems even harder to get it smooth, and it appears brittle.
We don't have any construction height left, so we can't install any panel materials. We have a fixed/embedded floor drain in a corner. We also don't want any dense materials like XPS, etc.
I have some respect for the difficulty of getting the concrete smooth. The starting point is that the lightweight concrete wall is already basically smooth.
Does anyone have experience? Are there any shortcuts? Smart tools?
P.S. A professional company (seller of masonry/plaster products) we spoke to also wondered if it's sensitive to have lightweight concrete in a moist area. Even though it's inorganic, it "stores" a lot of water/moisture if exposed. We might be able to have a foil membrane against these walls since they are externally insulated/drained. Interested in input on this too. I've always thought it would be trouble-free with the walls. (Outside the lightweight concrete there's a 2 cm air gap + 25 cm concrete blocks). We haven't had any previous moisture problems, and this has been used as a shower room since the house was built.
