I want to insulate underneath our suspended timber floor which has 100mm joists. As these aren't very big joists I wanted to use celotex or equivalent as this has a better insulation value than rockwool or similar.
I'm concerned though that we intend to finish the floor by laying luxury vinyl flooring on top of the floorboards, which will mean we will have sandwiched the floorboards between two vapour impermeable layers (the rigid insulation board and the luxury vinyl floor).
Is this a bad idea?
The crawl space is well ventilated and deep (about 80cm). The current joists have about 15% moisture content according to a meter.
