Fiberglass and Cellulose performing differently in attic
In our vented attic, we specified 18″ of blown-in cellulose. In one particular location, the insulation contractors were called back to redo an area that was not covered. When it got cold outside, I noticed that the ceiling in that area was noticeably colder than in other areas. Suspecting that the insulation contractor didn’t actually fix it, the builder and I went to the attic today to check. They had attempted a fix. Instead of putting cellulose in the problem area, they had installed fiberglass batts. The batts looked to be about the same thickness as the cellulose. We are going to have the contractor return and do what we specified. However, I am wondering why the fiberglass wouldn’t have performed about the same as the cellulose. I would have expected them to be similar but, based on the ceiling temperature, the fiberglass is noticeably inferior.