Is it worth it to add more attic insulation on top of R-40?
My house was built in 1989, the attic originally had fiberglass batts with loose fill rock wool. A couple of years ago cellulose was added to bring the overall R value to about 40 (hard to calculate exactly because the weight of cellulose also compressed whatever that’s beneath it). Now with $300 I can add 4 more inches of cellulose to bring it to about R50. Is it worth the cost?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part