Opened up a fire-rated wall to install stuff and discovered blackened sections in the insulation (i think it’s fiberglass). marks have no distinct pattern.
Should i reuse it? Should i add something else before closing up?
It’s sandwiched between 5/8" drywall and a concrete wall to a common area in building. Opening is 40" high from finished floor to ceiling. I don’t think there could have been water there, other than maybe condensation. That stuff is 33 years old.