R-Value (Thermal Resistance)

Category: science

The measure of an insulation material’s capacity to resist heat transfer flow.

A higher R-value signifies greater insulating effectiveness. R-value performance scales with the thickness and density of the chosen material (such as fiberglass batts, rockwool, or spray foam). Building zones dictate specific minimum R-values for attics vs. crawlspaces to control heat migration.

Common Examples

• The local energy ordinance requires an R-38 insulation barrier across the attic floor to insulate the home from summer heat peaks.
• Blown-in cellulose provides a higher R-value per inch of thickness than traditional loose fiberglass insulation configurations.