The exterior of fiberboards contains a foil covering that serves as both equally an air and dampness barrier. By themselves, fiberboard ducts are fantastic insulators and don't demand any more insulation. Insulation: Good insulation of ductwork, specifically in unconditioned Areas, helps preserve air temperature since it moves in the method, https://flexible-ducting-pu48046.wikiap.com/1538141/details_fiction_and_pu_ducting_sheet