Johns Manville has released a flexible fiberglass duct liner with an R-12 thermal resistivity rating. This insulation is designed specifically to meet the new code requirements set forth by the IECC in 2015 that mandate the use of R-12 insulation on ducts in unconditioned spaces in climate zones 5-8.
The company explained that this new 3-in. liner should be valuable to contractors working in those climate zones. Prior to the new Linacoustic RC product, single-layer, flexible R-12 duct liner was not an available option for the market. As a result, contractors were forced to use two layers of insulation to meet the R-12 standard. The new R-12 duct liner meets the code in just one layer.