How thick is r15 insulation?

R15 insulation typically has a thickness of about 3.5 to 5.5 inches, depending on the material used. For example, fiberglass batts designed for 2x4 walls generally have a thickness of around 3.5 inches, while other products might vary slightly. The R-value indicates thermal resistance, with R15 providing a moderate level of insulation suitable for certain climates and applications. Always check specific product specifications for precise measurements.