Duct insulation is thermal and acoustic material applied to ductwork to prevent heat transfer between conditioned air and surrounding spaces. This insulation reduces energy losses, prevents condensation, and controls noise transmission through the duct system. Properly insulated ducts improve system efficiency by 10-15% and enhance occupant comfort by reducing noise levels.
Material Types and Specifications
Fiberglass wrap with vapor barriers provides R-values of 3.3 to 8 per inch of thickness. Rigid fiberglass boards offer R-values up to 6.5 per inch and provide structural support. Foam board insulation delivers R-values of 5 to 7 per inch. Supply ducts in unconditioned spaces should maintain R-8 minimum, while return ducts require R-6 minimum according to ASHRAE standards. Ductwork in attics and crawlspaces demands higher R-values due to temperature extremes.
Installation and Performance
Proper insulation installation includes complete coverage, sealed joints, and intact vapor barriers to prevent moisture infiltration. Condensation forms on uninsulated cool supply ducts when surrounding humidity exceeds 60 percent relative humidity. Energy losses through uninsulated ductwork in attics can exceed 20 percent of total system capacity. Commercial ductwork typically requires R-8 insulation for optimal efficiency and indoor environmental quality.