This post first appeared on the Green Building Advisor Website
I recently wrote a two-part article covering the benefits, challenges and code requirements for continuous insulation. (You can read the articles here and here.) In the first article, I referenced table R402.1.3 which is found in Chapter 11, Energy Efficiency. The table shows the R-value and U-factor requirements for several building components and assemblies. The table data was taken from the first edition printing of the 2021 IRC. In the article, I stated, “Climate zones 1, 2, and 3 are unique in that they have the option of cavity-only insulation. Climate zones 4 through 8 all are required to have some amount of continuous insulation.” A reader on the Green Building Advisor Website, jimmybpsu, pointed out in the comments section of the article that he had a different version of table R402.1.3 which did allow for cavity only insulation in climate zones 4-8. As it turned out, he was right.

Continue reading “Cavity Only Insulation-A Correction to the 2021 IRC Energy Code”