Well here goes.. Last Spring I put an imperial rib metal roof on a cabin. The interior is I guess what you could call timber framed with about 2 1/2" thick tounge and groove finished cedar for a ceiling. This also doubles for the roof deck. The roof was shingled and I removed them down to the deck. damn. I then fastened 2x4's on edge perpendicular to the ridge on 16" centers. We were trying to add some room to insulate as well as create a cold roof to control ice. We then insulated the cavities with fiberglass faced insulation. We attached 3/4" perlings for the metal on 24" centers parallel with the ridge, and screwed the metal down. I now have what I believe to be a condensation nightmare in the middle of a northern michigan winter. Its leaking very bad. I know now that I should have at least tar papered over the existing deck but I didn't. I'm thinking my only solution is to remove all the metal and perlings, then sheath over the 2x's w 7/16" osb, add a vapor barrier and hope for the best.. But I'm wondering if the osb will condensate as well??? I dunno any help or advice would be greatly appreciated.