In insulation, the 'R' value is a measure of what property?

In insulation, the 'R' value is a measure of what property?

• A. Flame spread rating
• B. Smoke developed rating
• C. Measure of thermal resistance
• D. Measure of permeability

Answer: (C)

R-value measures how well insulation resists heat flow. It reflects thermal resistance—the higher the R-value, the better the insulation slows heat transfer. This isn’t about flammability, smoke production, or how permeable the material is to air or moisture, which are different ratings. In practice, more thickness or a material with lower thermal conductivity increases the R-value, and different layers’ R-values add up in a building assembly. So, higher R-value means stronger resistance to heat transfer, improving energy efficiency.

R-value measures how well insulation resists heat flow. It reflects thermal resistance—the higher the R-value, the better the insulation slows heat transfer. This isn’t about flammability, smoke production, or how permeable the material is to air or moisture, which are different ratings. In practice, more thickness or a material with lower thermal conductivity increases the R-value, and different layers’ R-values add up in a building assembly. So, higher R-value means stronger resistance to heat transfer, improving energy efficiency.