Double wall duct is constructed with a fiberglass insulation layer between a solid metal outer shell and either a perforated or solid inner shell. Both rectangular and round duct are available in double wall configurations.

Double wall duct has both acoustical and thermal insulation advantages. Acoustical double wall duct has a solid outer shell and a perforated inner shell to effectively reduce system noise. Thermal control double wall in constructed with solid inner and outer shells for assured thermal conductivity and vapor barrier integrity.

All double wall rectangular duct is fabricated with TDF connections and Pittsburgh longitudinal seams. One important advantage of double wall duct is that fiberglass insluation and sheet metal screws are not exposed to the airstream, permanently protecting the insulation and eliminating the possibility of it disconnecting from the outer shell of the ductwork.

Double wall duct is ideal for applications such as schools, hospitals, and laboratories. In exposed duct settings, double wall has a clean look that is much more aesthetically pleasing than externally insulated duct.