Attic insulation, especially fiberglass, should be replaced every 15-20 years, particularly if it has been exposed to moisture or mold.
R21 insulation is approximately 5.5 inches thick. This type of insulation is often used in walls and provides a higher R-value compared to standard insulation options, contributing to improved energy efficiency and thermal comfort in residential and commercial buildings.
Use R-19 or R-21 kraft-faced fiberglass insulation for 2x6 walls to ensure it fits snugly without being too loose or too tightly packed.