Can hold-down clamps on a trapeze cause duct leaks?

Answer

A trapeze clamp that dents the duct or flange is too tight or missing a protective pad. It can open corners, distort joints, and create noise.

Loosen the hardware, inspect the flange/corner, add approved cushion or bearing material, and tighten only enough to restrain movement without changing duct shape.

Field checks

• Look for crushed bottom skin, flange gaps, or corner leaks.
• Check whether clamps are bearing on a joint or flange corner.
• Add approved cushion/isolation where required.
• Tighten evenly without oil-canning the duct.
• Retest leak/noise if the joint was distorted.

Ask foreman

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Why this matters

Crushed duct changes shape, opens leaks, transfers vibration, and creates punch-list repairs.

Final direction still comes from approved drawings, specs, manufacturer instructions, employer policy, foreman/detailer direction, structural/seismic details, and AHJ/code requirements.