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Apprentice answer

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

3rd YearMeasuring, Layout & Field MathStop and get direction

A wide open floor penetration is a rated-assembly problem. Stop and firestop/sleeve it only by the approved listed detail.

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Plain-English 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.

Ask Foreman

The core hole around the spiral riser at [location] has a wide open gap through the slab. I checked that it is a floor penetration. Do you want this held for the approved sleeve/firestop detail?

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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