> Hart&Cooley. SUBMITTER DRAWING install confidence POLYETHYLENE VAPOR BARRIER INSULATION RIGID DUCT (NOT INCLUDED) STARTER CONE SLEEVE IS SHOWN INSTALLED THERMAL CHARACTERISTICS R-value of 4.2 when measured per MAST C518 at 75°F mean temperature based on insulating same duct size. «1.25 inch thick, 0.75 PCF density glass fiber insulation has a C factor of 0.23 «Formaldehyde free insulation VAPOR BARRIER «A durable black polyethylene vapor barrier «Perm rating of 0.