What is the thermal value per inch of thickness for polyisocyanurate roof insulation?

What is the thermal value per inch of thickness for polyisocyanurate roof insulation?

• A. 5
• B. 3
• C. 7
• D. 9

Answer: (A)

Thermal value per inch is the R-value gained for each inch of insulation thickness—the higher that per-inch number, the more heat resistance you get from every inch. For polyisocyanurate roof insulation, that per-inch value is about five. So one inch of polyiso provides roughly R-5, and thickness stacks to give the total R-value you need. The other numbers don’t fit typical polyiso performance: they would correspond to different materials or unusually high values for this material.

Thermal value per inch is the R-value gained for each inch of insulation thickness—the higher that per-inch number, the more heat resistance you get from every inch. For polyisocyanurate roof insulation, that per-inch value is about five. So one inch of polyiso provides roughly R-5, and thickness stacks to give the total R-value you need. The other numbers don’t fit typical polyiso performance: they would correspond to different materials or unusually high values for this material.