Duct insulation of commercial building including fire damper sleeve, fire damper , rockwool and weak concrete fillers ,concrete slab , also provided( 50mm x50mm x3) thick steel angle ,6mm clearance ,duct insulation ,access door as per SMACNA ,that provided on concrete slab These ducts are typically tube-shaped and made of a wire coil covered with a bendable, durable plastic, and surrounded by insulation., for more details of Duct insulation of commercial building download this file.