We have a part of our house that is an "excavated" part of the split-level section (underground). It was originally filled with gravel and has poured concrete walls. The previous owner dug it out, so it is a "room" with gravel as the floor and lightweight concrete walls. Two of the walls are exterior walls, one completely underground, the other about 50% (sloping) underground and has a window.
The room is "dry," the exterior walls are made of 40 cm Ytong blocks and drained with Platon on the outside. The floor is also dry, even if I dig down 20 cm.
The Floor:
The plan is to put 100mm isodrän on the ground, then a ground cloth and 150mm EPS cement on top of that. After that, lay out water-based underfloor heating and then 40mm fiber-reinforced self-leveling screed and just do floor leveling in the shower (sloping with a wall-mounted floor drain).
I plan to put a waterproofing membrane on the entire floor because there is insulation underneath.
I am more uncertain about the walls... I first looked at Fibo waterproof panels, but see that they have an organic backing and should be glued to concrete/lightweight concrete walls, and I naturally don't want to glue anything organic to the exterior wall.
The next thought was to build an "air gap" between the exterior wall and Fibo that I can mechanically ventilate, but it seems a bit tricky to achieve with stability since I don't want to place wooden studs against the exterior wall, and I want an "air channel" in the studs so that it can be ventilated...
The next idea is, of course, just tiling directly on the lightweight concrete, but in the laundry room (which is a similar excavated pit), I have had the problem where some moisture comes through the exterior wall, and tiles have fallen off. I rebuilt there and instead plastered the exterior wall, which has worked better. Moisture doesn't come in so that it becomes "wet," but apparently enough to affect the tiles/adhesive.
I also considered diffusion-open waterproofing against the exterior walls, mainly to prevent bathroom moisture from reaching the exterior walls, but thought it might slow down any moisture migration so that tiles on the wall could work and stay up...
Thoughts?
The room is "dry," the exterior walls are made of 40 cm Ytong blocks and drained with Platon on the outside. The floor is also dry, even if I dig down 20 cm.
The Floor:
The plan is to put 100mm isodrän on the ground, then a ground cloth and 150mm EPS cement on top of that. After that, lay out water-based underfloor heating and then 40mm fiber-reinforced self-leveling screed and just do floor leveling in the shower (sloping with a wall-mounted floor drain).
I plan to put a waterproofing membrane on the entire floor because there is insulation underneath.
I am more uncertain about the walls... I first looked at Fibo waterproof panels, but see that they have an organic backing and should be glued to concrete/lightweight concrete walls, and I naturally don't want to glue anything organic to the exterior wall.
The next thought was to build an "air gap" between the exterior wall and Fibo that I can mechanically ventilate, but it seems a bit tricky to achieve with stability since I don't want to place wooden studs against the exterior wall, and I want an "air channel" in the studs so that it can be ventilated...
The next idea is, of course, just tiling directly on the lightweight concrete, but in the laundry room (which is a similar excavated pit), I have had the problem where some moisture comes through the exterior wall, and tiles have fallen off. I rebuilt there and instead plastered the exterior wall, which has worked better. Moisture doesn't come in so that it becomes "wet," but apparently enough to affect the tiles/adhesive.
I also considered diffusion-open waterproofing against the exterior walls, mainly to prevent bathroom moisture from reaching the exterior walls, but thought it might slow down any moisture migration so that tiles on the wall could work and stay up...
Thoughts?