What are the Insulation R-Values of Foam Insulation Boards?
Expanded, extruded, and cut bead polystyrene insulation products have an R-value of about 4.0 per inch of thickness. Typical exterior foam board building insulation sheets have an R-value of 2.64 per inch. Expanded polyurethane building insulation products have an R-value of about 5.0 per inch of thickness. Expanded polyurethane insulation expanded using the refrigerant gas has an R-value of about 6.25 per inch. Polyisocyanurate insulation products have an R-value of about 7.04 per inch. [ASHRAE Fundamentals Handbook.] To compare insulating material R-values see our Table of Properties of Insulating Materials Also see Mold Growth Resistance of Foam Insulation, and see INSULATION INSPECTION & IMPROVEMENT for details about foam and other building insulation types; see FIBERGLASS HAZARDS for a discussion of mold problems in fiberglass insulation; see Mold On Foam Insulation for a discussion of when and why we find mold growth on foam insulating materials like foam board and air handler fo
