My new shop has one inch hard foam sheeting between the stringers and the metal with r-30 batt insulation in the walls and ceiling before being sheeted with either metal or osb. It's like a cooler, super easy to keep warm or cool and you have finished walls for anything you want to do.
...have you had any issues with condensation?
Looking for better Gulf items: signs, globes, cans and paper - especially porcelain Gulf flanges, and Gulf A-38 & A-62 ad glass...