I'm based in Scotland and have a 40 foot by 10 foot tongue and groove shed that is used to store clothes for my business. It sits slightly above ground on a wooden base. I have added a metal roof on top of the existing wooden one. Inside I have put in a false floor and I've also screwed plywood over joists on ceiling.
On the walls all around I’ve firstly left an air gap of 2 inches before fitting in foam insulation sheets then stapled VC moisture barrier silver backed foil to joists before screwing plywood onto the joists and lastly used sealant to seal every little gap.
The problem is that in winter it is freezing and summer stifling hot And after a few years now I’m starting to smell a stale dampness and worried that it will transmit to my clothes stock.
So my question is should I heat or dehumidify put in air vents or all