The outside of fiberboards contains a foil masking that serves as both an air and moisture barrier. On their own, fiberboard ducts are fantastic insulators and don't involve any more insulation. Standard cleaning and upkeep in the ductwork may help improve indoor air high quality and reduce well being dangers. https://ducting-polyurethane25791.xzblogs.com/76050287/details-fiction-and-pu-ducting-sheet