Posted on March 26,2015 by Peterbilt in Add a floor above
**Although they’re theoretical, whole-wall R-values are closer to real life insulating values.**
Consider a 2x4-in. wall framed 16-in. O.C. and stuffed with high-density R-13 fiberglass batts. Assuming a perfect installation, its whole-wall insulation value is closer to R-10 (25% to 30% less) due to thermal bridging caused by wall studs, plates, and the band joist. This problem is particularly acute with steel framing. And, more difficult to measure, the true insulation value likely is even less because of poor installation, air infiltration, wind wash, air-convection loops, etc.