Apprentice answer

What if an FSD sleeve gap is packed with regular fiberglass

2nd YearDampers, Fire/Smoke & Life SafetyStop / 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.

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Plain-English answer

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.

Field checklist

Confirm wall rating, damper type, sleeve, retaining angles, and gap condition.
Check the damper manufacturer installation sheet and approved firestop detail/submittal.
Identify whether the existing material is approved for that exact assembly.
Stop wall/shaft cover until the firestop condition is corrected and documented.
Take photos before and after correction for inspection/closeout.

Ask Foreman

The FSD sleeve at [location] has regular insulation packed around the wall gap. I checked the damper tag and wall rating. Do you want this removed and replaced per the approved firestop/listed assembly before cover?

Verify before acting

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.

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