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Feedback on this Metal Roof Assembly

E247 | Posted in General Questions on

I have a question about the insulation installed in a small house.  The house is a small house that has a cathedral ceiling from end to end.  The roof has 2×10 rafters with fiberglass batts installed between the rafters.  There is metal roofing installed on both the outside and inside, so you effectively have fiberglass batts sandwiched between metal roofing.  I don’t know if there is plywood on the roof decking or any venting.  Is there any concern with this type of installation?  The house is in climate zone 2.

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  1. E247 | | #1

    I have a few more details after seeing some pictures. There is no sheathing, the metal roofing is installed directly on the rafters without any underlayment. Purlins were installed between the rafters and sit flush on top so the only ventilation gap is were the metal roof has ridges. The fiberglass batts were installed haphazardly, so there are significant gaps and places where there isn't any insulation.

    With metal on both the interior ceiling and exterior roofing as well as the poorly installed (or missing) insulation, I'm concerned there will be condensation issues. During the winter, the warm moist air from inside will reach the cold outside roof allowing condensation to form. During the summer when the inside is cool, the warm moist air from outside will reach the inside metal on the ceiling allowing condensation to form. Is this a valid concern?

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