What is the minimum R-value for duct insulation located outside of attics?

The minimum R-value for duct insulation located outside of attics is R-6. This standard is based on the need to ensure energy efficiency and minimize heat loss or gain in HVAC systems. Ducts that are installed outside of conditioned spaces, such as in unconditioned attics or external environments, require higher insulation levels to maintain temperature and reduce energy consumption.

R-value measures an insulation material's resistance to heat flow; a higher R-value indicates better insulating properties. If the insulation has an R-value of 6 or greater, it effectively limits the energy losses associated with the ducts, contributing to improved system efficiency and lower utility bills. Therefore, an R-value of R-6 is the minimum required for optimal energy performance in these scenarios.