I want to go with 4/12 prefab roof trusses, 24" o/c. I have to imagine that 2 x 4 purlins at 24" o/c should be plenty stout. A 4/12 pitched metal roof should shed snow fairly well...? This being true, laying them flat should be reasonable practice...? Besides, what type/length of fastener would be used to go thru 3.5" of inverted 2 x 4, plus seat/bond with the support member?
