How to protect stuff from damp in my shed.
(Southern England, UK)
I have a shed provided by our housing association. It's basically a long block, brick built building, that has been split into 6 sheds that have a concrete base. Each brick shed has a wooden door. I think the roof is possibly a type of concrete, and covered in roofing felt. There's no ventilation I can see, other than the fact that the door doesn't sit perfectly in the frame.
In the shed, I currently store my bass amplifier, which has a paper cone (15inch). I've made a plastic cover for it, but obviously concerned about damp. The reason I don't keep it inside the flat, is that it weighs 50kg and I'm on the 4th floor, and there's no lift.
What can I do to improve the damp proofing in the shed, that doesn't involve structural work (which we're not allowed to do). I wondered if I could build an insulated frame sitting inside the shed - plastic membrane on the floor, thin insulation on the walls and door?
Any help much appreciated.