Peter from Toronto wanted to know about installing a linen closet against an outside wall. The major concern expressed by Jon was the moisture issue, as the closet is in a bathroom.
The bathroom must have an exhaust fan to reduce the moisture accumulation.
The outside wall of the closet should have an additional one inch of Styrofoam over the whole surface, and then drywall over that. This "inside sheathing" will insulate the studs in the walls and prevent any cold spots on the wall that would encourage condensation. Also, the wall to floor crack should be caulked tight to prevent any chilling caused by cold air drafts. Louvered doors would be the best to keep the linen closet aired out as much as possible.