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I have a metal roof mounted on furring strips which are nailed to 2×6 rafters. I have R-19 Kraft faced insulation between the rafters with rafter vent chutes to create an air space between the roof and the insulation. I am getting large amounts of condensation this winter (in PA) which is staining/damaging the ceiling below. There is no venting in the attic space between the rafters and ceiling below. Other parts of the house that don’t have a metal roof (plywood sheathing/shingles) are not getting condensation. What can I do to alleviate the condensation problem?
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Patrick,
Remove the vent chutes and the R-19 fiberglass. Spray Icynene (or similar foam) on the underside of the metal. Works every time. Do not ventilate the attic space below.
*Except in barns where condensation doesn't pose as much of a problem, metal roofing should be installed on felt covered plywood or OSB, and not on purlins. Sue V.'s solution will have to be the fix on my next call as well. Hey, thanks Sue!fv
*We have been putting on steel roofs for years mostly on farm buildings. When we install a roof on a building we use a fan fold insulation directly under the steel to keep the moisture off of the cold steel and we haven't had any problems. By doing it this way you don't have to use any other sheathing. We have also done this on houses and didn't have any problems either.
*Sue, thanks for the great idea. Just two more questions...How thick should the Icynene be, and is it okay to reinsulate after applying the Icynene?
*PatrickWhy would you want to reinsulate? Icynene (or other types of spray foam) are in themselves insulation. As for the thickness, 4-6 inches is all you need. check out icynene's web site - icynene.com or do a web search on insulation+foamVince
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I have a metal roof mounted on furring strips which are nailed to 2x6 rafters. I have R-19 Kraft faced insulation between the rafters with rafter vent chutes to create an air space between the roof and the insulation. I am getting large amounts of condensation this winter (in PA) which is staining/damaging the ceiling below. There is no venting in the attic space between the rafters and ceiling below. Other parts of the house that don't have a metal roof (plywood sheathing/shingles) are not getting condensation. What can I do to alleviate the condensation problem?