An unvented attic is where you insulate underside of the roof deck including the gable walls to the appropriate R-value for the
roof of a home in you climate zone. The attic floor should not have any insulation or vapor retarder installed. If the attic area has direct ventilation using AC ducts, then it may be classified as a living space where the foam would have to be covered by a thermal barrier such as gypsum board. Otherwise, direct ventilation should not be installed in this attic area.
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Jason M. Hoerter, P.E.
Sr. Product Manager
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