Does a Steel Roof Required an Underlayment?

http://fernandolstd771.unblog.fr/2020/05/17/owens-corning-tiles-period-how-long-do-they-last/

Outside air flows in at the end of the roofing, follows the underside of the roofing deck, and then brings warm as well as moisture from the attic room, out of the attic room space with the exhaust vents. We think