TinnerFlow™2nd YearFire/Smoke DampersRED · Stop / Verify
Regular insulation is not automatically an approved firestop. Stop cover, verify the listed assembly/firestop system, and replace improper packing with the approved material/detail.
The gap around a damper sleeve through a rated wall is part of a listed/rated assembly. If someone stuffed it with random fiberglass, it may look filled but still fail inspection or life-safety requirements.
Do not guess the firestop product from memory. Check the damper installation instructions, wall rating, approved firestop submittal/UL system, and project detail. The likely fix is to remove the wrong material and install the approved mineral wool/firestop/wrap/caulk system exactly as specified.
Use this as training guidance. The foreman, approved drawings, project specs, manufacturer installation instructions, employer safety policy, and AHJ/code requirements always control the final answer.