I have a doublewide, 1983 I think. Time to replace the roof, currently shingles. Going to use metal. The roof trusses are 2', not 16" on center. The roof bows slightly between each truss, and is slighty spoungie. From in the attic, I see no bow, but each truss is built with 1 1/4"x1 1/2" wood, not 2x4s. Can I just place the new metal roof ontop of it, as everyone says. Personally I'd replace the whole thing, or build a roof over this one. Drill pile supports and all. I'm not sure if i can trust what will be left under the metal I install. Any ideas?