If the R value on a section of insulation is 8, what would the value be when saturated with water?

If the R value on a section of insulation is 8, what would the value be when saturated with water?

• A. 0
• B. 12
• C. 8
• D. 4

Answer: (A)

R-value measures how well a material resists heat flow—the higher the value, the better the insulation. When insulation becomes saturated with water, the air spaces that provide most of the resistance are filled with water. Water conducts heat much better than air, so the material loses its insulating effectiveness and its ability to resist heat drops dramatically. In this situation, the R-value is effectively zero, which is why the correct choice is 0. The other options would imply some remaining resistance, which doesn’t happen once water fills the pores and conducts heat more readily.

R-value measures how well a material resists heat flow—the higher the value, the better the insulation. When insulation becomes saturated with water, the air spaces that provide most of the resistance are filled with water. Water conducts heat much better than air, so the material loses its insulating effectiveness and its ability to resist heat drops dramatically. In this situation, the R-value is effectively zero, which is why the correct choice is 0. The other options would imply some remaining resistance, which doesn’t happen once water fills the pores and conducts heat more readily.