The roof structure sagged, and my duct is now hitting the ceiling grid. How do I re-engineer the run on the fly

Plain-English answer

Do not try to smash the duct flat or force the ceiling grid tracking down out of square. * Calculate the exact clear height variance dimension remaining. If the duct is a low-pressure line, you can transition the run from its original deep square dimensions (e.g., 24\text{ in} \times 24\text{ in}) into a wider, flatter rectangular aspect profile (e.g., 36\text{ in} \times 16\text{ in}) that preserves the exact same internal cross-sectional area footprint and matching velocity parameters while gaining the necessary overhead clearance.

Field checklist

• Stop and verify the approved detail, manufacturer instructions, foreman direction, and project specs before touching it.
• Do not try to smash the duct flat or force the ceiling grid tracking down out of square. * Calculate the exact clear height variance dimension remaining. If the duct is a low-pressure...

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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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