On Oct 14, 3:33*am, "DanG" wrote:
29 gauge liner sheets or galvanized "barn tin" *would span the 4'
spacing just fine, and hold insulation if desired. *I would be
confident the trusses could take the load.

While that would work for support, It would constantly drip water
except during the summer months. Even the metal roof will have to have
good venting, but will still sweat.

Paul