As part of refurbishing my dad's bungalow I must lift the dining room floorboards to stabilise the joists (bouncy floor) and modify some water/heating pipework. The existing boards are at the end of their life, so I am going to re-floor with 8'x2' (21mm) chipboard sheets. I am going to insulate between the 6" joists with 100mm foil faced Celotex supported from below with roofing battens screwed either to the side or underside of the joists.
The question is a simple one. Should the foil face be hard up against the underside of the new chipboard flooring? Some I have asked say 'yes', some say to leave a 1" gap so air can flow, but surely that defeats the object of trying to trap the heat in the room above. Each is convinced they're right, but what is the verdict of the skilled DIYnot contributors, AND WHY.
Regards, MM
The question is a simple one. Should the foil face be hard up against the underside of the new chipboard flooring? Some I have asked say 'yes', some say to leave a 1" gap so air can flow, but surely that defeats the object of trying to trap the heat in the room above. Each is convinced they're right, but what is the verdict of the skilled DIYnot contributors, AND WHY.
Regards, MM