Coverage and R-value for attic, wall, or floor insulation.
R-value measures thermal resistance — higher is better. For attics, the DOE recommends R-38 to R-60 depending on climate zone. For walls, R-13 (2×4 construction) or R-19 (2×6) is standard. For crawl spaces and basement walls, R-10 to R-15 is typical.
Blown insulation achieves better coverage in existing walls and irregular spaces. Batt insulation is easier to install in new construction with accessible cavities.