Fiberglass duct board (preinsulated non-metallic ductwork

Fiberglass duct board (preinsulated non-metallic ductwork)[edit]

Fiberglass duct board panels provide built-in thermal insulation and the interior surface absorbs sound, helping to provide quiet operation of the HVAC system.

The duct board is formed by sliding a specially-designed knife along the board using a straightedge as a guide. The knife automatically trims out a groove with 45° sides which does not quite penetrate the entire depth of the duct board, thus providing a thin section acting as a hinge. The duct board can then be folded along the groove to produce 90° folds, making the rectangular duct shape in the fabricator's desired size. The duct is then closed with outward-clinching staples and special aluminum or similar metal-backed tape.