What is the R-value per inch range for cellulose insulation?

• A. 6.5–7.0
• B. 3.0–3.3
• C. 3.6–4.2
• D. 3.5–3.8

Answer: (D)

R-value per inch is how much thermal resistance each inch of insulation provides. Cellulose insulation typically yields about R-3.5 to R-3.8 per inch, due to its dense, fibrous structure that limits air movement and convection inside the material. This makes it a higher-per-inch option than many other common insulations. While actual field values can vary with installation density and moisture, the standard range used is 3.5–3.8 per inch, which matches the given choice.