I am constructing a lightweight exterior wall. From inside to outside, it consists of double plasterboard, 45 horizontal wooden studs with MU, vapor barrier, 220 vertical wooden studs with MU, 50 grooved foam plastic, 34 vertical battens (air gap), inorganic board, and thin plaster.
My question is whether I need to have an inorganic board inside the grooved foam plastic? I can't see the benefit of it, but maybe I've missed something?
