Hello!
I have a room in the attic of an older vacation/timber house, which is completely uninsulated and directly against the outer roof, as you can see according to the picture.
In winter it becomes terribly cold, constantly below freezing, and in summer it becomes instead warm.
I'm considering preparing the space as a small gym during summer and fixing the walls a bit to add more charm and make the room brighter, my question to you is:
What material for the walls is durable under these conditions?
I was considering drywall directly against the wall but am not sure how it holds up in 6 months of constant freezing and possible moisture.
Grateful for tips and suggestions!

