I am going to install water-based underfloor heating in the small hallway. I dismantled the existing click flooring, and underneath it was a vinyl mat, and under that, another mat glued to the floorboard. Directly under the board, there was plastic just above 40 mm of cellular plastic. Below everything is the concrete slab. It is a slab on ground.
Now to the questions. Since I intend to install water-based underfloor heating (was it 16 mm pipes, right?), I can only fit 30 mm of cellular plastic. I plan for the concrete I pour to be about 45 mm max. (I have about 80 mm to play with to the finished floor with tiles.)
Do I need to place plastic above the cellular plastic to eliminate any potential ground moisture? Do I need to make the floor floating, and as far as I understand, I then need so-called perimeter strips all around?
