Apprentice answer

How much expansion clearance do I need to leave around a fire damper sleeve

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

The rough wall framing opening must be larger than the damper sleeve. The general standard rule of thumb is leaving \frac{1}{8} inch of clearance per linear foot of damper width and height, or a strict minimum of \frac{1}{2} inch total clearance gap around the entire sleeve perimeter, unless specified otherwise by the UL installation listing sheet.

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Plain-English answer

Field checklist

Stop and verify the approved detail, manufacturer instructions, foreman direction, and project specs before touching it.
The rough wall framing opening must be larger than the damper sleeve. The general standard rule of thumb is leaving \frac{1}{8} inch of clearance per linear foot of damper width and...

Ask Foreman

Hey boss, I’m on dampers and need verification before I touch this: How much expansion clearance do I need to leave around a fire damper sleeve? Do you want me to stop here and check the approved detail, submittal, or inspector/manufacturer requirement first?

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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