Problem with damp inside a wooden shed
I insulated my wooden shed (which sits on a concrete block) using foil faced insulation that comes on a roll. I then used hardboard to line out the inside. There is clearly a problem with damp as the hardboard has gone black and I’m having to run a dehumidifier 24 hours a day.
can I simply paint the shed interior and if so what sort of paint should I use?
what can I do to rectify the problem that
a - won’t be costly
b - won’t, hopefully, require ripping all the insulation and hardboard out
Thank you for your help