said by Del_Gue:I know the fiberglass comes compacted and then expands, but will it expand after it has been allowed to age and it also has accumulated a little dirt and roofing shingle debris in places. Will compression affect R value?
They are vacuum packed when they are shipped.
Poke a hole in those bags and you'll see air whooshing in, and the plastic bag suddenly fighting for its life!
They probably won't fluff back to their original designed thickness, but it can't hurt to uncompress them. The debris won't do anything, they're too light.