In the basement of my split-level house, a bathroom is being renovated. The floor is broken up and soon a new floor with underfloor heating will be cast. To determine the exact position of the floor drains, I need to decide how to proceed here...
At least one interior wall must be framed out to make room for some pipes. To make it easier for me, I'm considering framing out at least one more wall, which is an exterior wall. The wall is made of lightweight concrete, and the ground level outside is at the same level as the indoor floor surface. Will I risk any kind of moisture problem if I frame out this exterior wall as well?
I think that moisture would somehow form behind the framed wall and the existing exterior wall, which will not be able to get out from there.
The yellow marked area is the wall above ground. The red marked area is the wall and footing below ground. The ground level is the same as the floor level. Under the cast floor, there is at the bottom a 10 cm Isodrän board, then 10 cm of foam insulation, radon barrier, and then another 10 cm of foam insulation. On top of that lies the concrete floor.
In the bathroom, there will be a waterproof membrane and tiles.
