My third floor is partcially finished and functioning with a full bath and apartment size kitchen as well as two more finished rooms. The front of my third floor is unfinished.

My idea is to give this room a loft look.

I would like to leave this area as natural as possible. The floor are raw/natural wood. I would like to have these only stained.

How could I insulate the side panals of the floors at the bottom where the natural arch begins and insulate the walls without completely covering up the exposed wood slats?