What is the R-value of cellular-glass board insulation?

What is the R-value of cellular-glass board insulation?

• A. 2.5
• B. 3.44
• C. 4.0
• D. 5.0

Answer: (B)

R-value measures how well a material resists heat flow—the higher the number, the better the insulation. For cellular-glass board insulation, its closed-cell structure and low thermal conductivity give it a relatively high resistance per inch. The standard, widely cited value for this material is about 3.44 per inch, so one inch of cellular-glass insulation provides roughly R-3.44 of resistance. For thicker sections, multiply the per-inch value by the thickness (for example, 2 inches would be about R-6.88). Temperature and moisture can shift the exact value a bit, but 3.44 per inch is the commonly used figure for typical conditions.

R-value measures how well a material resists heat flow—the higher the number, the better the insulation. For cellular-glass board insulation, its closed-cell structure and low thermal conductivity give it a relatively high resistance per inch. The standard, widely cited value for this material is about 3.44 per inch, so one inch of cellular-glass insulation provides roughly R-3.44 of resistance. For thicker sections, multiply the per-inch value by the thickness (for example, 2 inches would be about R-6.88). Temperature and moisture can shift the exact value a bit, but 3.44 per inch is the commonly used figure for typical conditions.