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Apprentice answer

Can a fire/smoke damper be installed at a 45-degree angle in a rated wall

3rd YearDampers, Fire/Smoke & Life SafetyStop and get direction

Do not angle a fire/smoke damper through a rated wall unless the listed assembly specifically allows it. Square the duct to the wall with approved fittings before the damper sleeve.

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Plain-English answer

Fire and smoke dampers are listed assemblies. The sleeve, retaining angles, damper frame, actuator, blade path, and wall opening have to match the installation instructions. A duct hitting the wall at 45° can put the damper out of square and bind the blades.

Stop before cutting a slanted rated-wall opening or forcing the sleeve. The likely recovery is to square the duct path before the wall using approved elbows/offsets, or get a detail from the foreman/detailer/engineer.

Ask Foreman

The duct approaches the rated wall at a 45 and the damper will not sit square in the sleeve. I stopped before cutting/setting it. Do you want an upstream offset to square the duct to the wall or a detailer RFI?

Verify before acting

Use this as training guidance. Foreman direction, approved drawings, project specs, manufacturer instructions, employer safety policy, and AHJ/code requirements always control the final answer.

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