Polyisocyanurate rigid board insulation has an R-value per inch of approximately what?

Polyisocyanurate rigid board insulation has an R-value per inch of approximately what?

• A. 7.0
• B. 3.0
• C. 5.0
• D. 4.0

Answer: (A)

R-value per inch measures how much resistance to heat flow a material provides for each inch of thickness. Polyiso rigid board insulation delivers a high amount of resistance for its thickness, making it one of the most efficient common insulation options on a per-inch basis. The approximate value used in practice is about 7.0 per inch in imperial units, which is why that option is the best fit. For example, two inches would be around R-14. This is higher than many other insulation types, so it explains why even a relatively thin layer of polyiso can achieve strong overall insulation.

R-value per inch measures how much resistance to heat flow a material provides for each inch of thickness. Polyiso rigid board insulation delivers a high amount of resistance for its thickness, making it one of the most efficient common insulation options on a per-inch basis. The approximate value used in practice is about 7.0 per inch in imperial units, which is why that option is the best fit. For example, two inches would be around R-14. This is higher than many other insulation types, so it explains why even a relatively thin layer of polyiso can achieve strong overall insulation.