Which of the following is true about R-value and insulation performance?

• A. Higher R-value indicates greater resistance to heat flow
• B. A lower R-value provides better insulation
• C. R-value only applies to reflective surfaces
• D. R-value measures moisture resistance

Answer: (A)

R-value measures how well an insulation material resists heat flow. The higher the R-value, the greater the resistance to heat transfer, which means the insulation is better at keeping heat in during winter and out during summer. This happens because R-value quantifies thermal resistance: as you increase thickness or use a material with higher inherent resistance, the overall heat transfer through the wall or attic drops. In practice, the total performance is the sum of the R-values in all the insulating layers, and the rate of heat transfer is the reciprocal of that total (often described as U-value).

So why the other ideas aren’t right: a lower R-value would let more heat through, not less, so it doesn’t provide better insulation. R-value isn’t limited to reflective surfaces; it applies to the insulating materials themselves in a given assembly. And R-value doesn’t measure moisture resistance; moisture control is about vapor barriers and moisture content, not thermal resistance.