Duct sheets used: Galvanized Iron sheet, Aluminium Sheet and Pre-Insulated sheets.
Duct sheets are insulated from heat losses with mineral fibre, Rubber insulation sheet and sound proof cloth/ attenuators (does not apply to Pre-Insulated ducts)
Insulation thickness ranges from 6mm (1/4″) to 50mm (2″)
Special sheet glue is used to stick insulation on the metal sheets