Single skin metal roof uses only 1 metal deck sheet and is designed to provide an economical solution, normally used in applications where performance demands are moderate. Insulation for single skin metal roof is installed below the metal cladding sheet held by aluminum foil and steel wire mesh rolled over purlins. Whereas Double skin metal roof is a high performance roofing system comprising of 2 metal decking sheets aligning parallel, one on top and the other at the bottom. The metal sheet or metal tray can be steel, aluminum, copper, zinc, stainless steel or titanium. The two metal sheets are fixed together with a z-purlin creating a gap in the roof space for installation of insulation and vapor barrier.