A residential building is being constructed with a forced-air heating and cooling system. The contractor has installed a supply duct that runs through an unconditioned attic space. Which of the following is a requirement for the duct insulation according to the 2024 International Residential Code?
- AInsulation must be R-3 for all ducts.
- BInsulation must be R-6 for all ducts.
- Insulation must be R-8 for supply ducts and R-3 for return ducts.
- DInsulation must be R-13 for all ducts.
Exam tip
Remember the specific R-values required for duct insulation in unconditioned spaces.
Why C is correct
According to Section M1503.3.1 of the 2024 IRC, supply ducts in unconditioned spaces must have insulation with a minimum R-value of R-8, while return ducts must have a minimum R-value of R-3.