Brent Mason
1/14/2016
I enclosed my 12x20 porch . I installed metal roof on 2x4 16" C purlins and purlins screwed to the 24"C rafters . After completing enclosure and adding heat source I quickly saw the terrible condensation inside the metal ! I am asking for any opinions or ideas on the 2 ways I believe the condensation could be solved . #1 Spray at least 3" of closed cell foam up on inside of metal between and probably over the purlins . I was told by a foam company that 3" should resolve the moisure . #2 Use ADO Durovent http://adoproducts.com/as_durovent up inside the rafters and against the purlins . As you can see with #2 the Durovent would run inside the rafters from the house facia upper end down to and into the soffit area . Note there is a 2x6 where the roof originally ended but I added the overhang later . Thus where the Durovents go trhu that rafter I will need to cut out for the baffles to pass into the soffit area . Then at the upper end house facia end I would need to cut out or drill holes in areas between rafters into what would be the house attic . This should allow moisture drainage into soffit area and ventilation . Under the Durovent I would install fiberglass insulation and later probably plaster board .
Todd Miller
Classic Products, Inc.
1/15/2016
I feel that either method could work though the first one is probably simpler. You also could do both. If you only do the latter, I would suggest also adding a vapor barrier between your fiberglass insulation and the dry wall. The vapor barrier could be a sheet of 6 mil polyethylene.

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