The outside of fiberboards features a foil masking that serves as both equally an air and humidity barrier. On their own, fiberboard ducts are exceptional insulators and don't have to have any more insulation. Indeed, you could paint ductwork, but it is important to use the appropriate form of paint https://ductingpu32197.wssblogs.com/35369737/pu-ducts-can-be-fun-for-anyone