Mineral wool batts for 2×4 walls have an R-value of 15, while a standard fiberglass batt made to fit in a 2×4 wall has an R-value of 11 or 13. However, you can special-order R-15 high-density ...

Using traditional materials such as mineral ... The higher the R-value, the more thermally resistant your home will be. 'For attics, loose-fill glass wool is common; for walls, batts or blankets ...