Why is a big gap around round duct through a floor slab a fire/smoke issue?

Field answer

A slab opening around duct is not just an ugly hole. It can pass smoke, fire, noise, and air between floors if it is not sleeved and firestopped correctly.

Document the gap, confirm whether the floor is rated, and coordinate the approved sleeve/firestop/wrap/mineral wool/intumescent system before covering or turnover.

What to check first

• Measure/photograph the gap around the pipe.
• Confirm floor rating and penetration detail.
• Check whether a sleeve is required.
• Identify who owns firestopping on the project.
• Do not cover until the listed assembly is installed/inspected.

Why it matters

Bad floor penetration firestopping can fail inspection and compromise smoke/fire separation between levels.

Ask foreman

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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.