We’re talking simple addition: Say you buy one layer of R-19 fiberglass batting and stack ... Typical R-value: R-3 to R-4 per inch of thickness, though high-density fiberglass can go higher.

School of Civil, Environmental and Architectural Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea KU-KIST Graduate School of Converging Science and Technology, ...