Section SPS 322.42 - Duct systems(1) Supply and return heating ducts, or portions thereof, that are not located completely within the thermal envelope, shall be provided with insulation with a thermal resistance of at least R-8.(1m) Cooling supply ducts that pass through unconditioned spaces conducive to condensation, such as attics, shall be provided with insulation having a thermal resistance of at least R-8. The exterior of that insulation shall be covered with a vapor retarder that meets the requirements in s. SPS 322.38(1)(2) Building framing cavities may not be used as supply ducts.Wis. Admin. Code Department of Safety and Professional Services SPS 322.42
CR 08-043: cr. Register March 2009 No. 639, eff. 4-1-09.Amended by, CR 15-041: cr. (1m) Register December 2015 No. 720, eff.1/1/2016