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Foam insulation on metal siding

jeremec | Posted in General Questions on

I am building an all steel barn kit, I plan to use spray foam insulation on the walls and bottom side of the roof . do I need a vapor barrier between the metal siding and roofing or can the foam be sprayed directly to the inside of the metal?

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  1. GBA Editor
    Brian Pontolilo | | #1

    Hi Jeremec,

    I assume that you are talking about using closed-cell foam which is not vapor permeable, so you don't need a vapor barrier for vapor control. Something to keep in mind: spraying foam against siding and roofing will basically glue the building together and make remodeling and repairs a challenge. Not sure when you plan to do this work, but we have an article coming later this month on insulating metal buildings that may be helpful.

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