When homeowners receive quotes from HVAC contractors, they typically are given two duct replacement options, sheet metal or fiberglass duct board. There is a third option, phenolic duct, that is made of plastic foam with a foil liner on the inside and exterior. It hasn’t been on the market long enough to weigh in on its merits and shortcomings and will not be included in this comparison. Homeowners usually go for the product their HVAC contractor recommends; however, all systems have their strengths and weaknesses. Here are the advantages and disadvantages of two of these materials when installed in the typical residence.