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Apprentice Q&A · #353

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

3rd YearRED · Stop and get directionFire Wall Angle Clash

Short answer

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.

Field 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.

What to check first

Do not do this

Do not install a fire/smoke damper cocked at an angle through a rated wall because the duct line came in crooked.

Why it matters

A misoriented damper can fail inspection or fail to close correctly in a life-safety event.

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?

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Related Field Rescue route

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Final direction belongs to the foreman, approved drawings/specs, manufacturer instructions, pressure/material schedule, employer policy, and AHJ/code requirements.