Smell in the attic staircase

[DorisDoris]

House built - 54. In the stairway up to the attic, there's the original tension paper on the walls and a plastic mat on the stairs. The stairway is cold, likely lacking insulation in the walls there since it was intended to be a cold space. Upstairs, there's a bedroom, newly renovated, and a cold old attic. But I think there's a particular smell in the stairway. It doesn't smell directly bad, nor like mold or basement-like. Not even an attic smell (like old sawdust...) But something. I can't quite explain the smell. Could it be the old carpet and tension paper? What do you think? Under the stairway is partly the downstairs and partly the stairs to the basement. There's no smell on the ground floor. We are thinking of redoing the surfaces but are considering what would be good options. The space will probably remain cold. I don't want to add studs and insulate because it takes away some space and gets tricky at the doorway. Should one put vapor barrier paper on the walls before the new surface, whatever it may be (drywall, paneling, etc.)?

 

[sinuslinus]

What are the walls behind the cardboard?
The carpet on the stairs can just be torn off.

 

[DorisDoris]

What are the walls behind the paper?
The carpet on the stairs should just be torn off.

Old plank. Yes, the stairs aren't a problem in themselves. Remove the carpet and apply a new surface.

 

[sinuslinus]

Old raw wood planks. Yes, the stairs are not a problem in themselves. Remove the carpet and apply a new surface.

Plank wall then?
No insulation that molds?

 

[DorisDoris]

Plank wall then?
No insulation that molds?

As I wrote, they probably lack insulation entirely, and if there is any, it's sawdust. But it doesn't smell like mold or moisture or anything like that.

 

[sinuslinus]

There is no reason to install a vapor barrier.

The matting might produce odor, but it's hard to guess from a distance. Spännpapp is regular paper that is painted, so it shouldn't smell unless you have some tar paper behind it.