Hello!
I am about to start preparing an attic or a closet on the upper floor that lacks any tretex (fiberboard) and only has the frame construction (standing plank); all other walls upstairs have this...
I don't want to build out with 45*45 studs and add insulation internally as it will look strange when we are done with this space.
So the question is if there is any insulating ability in fiberboard, or is there any other material that can be used that doesn't add more than about 12-13 mm?
Polystyrene exists but I'm a bit skeptical about it on an exterior wall in a house from the 1930s...
Best regards, nikke
