Apprentice answer

Why is my duct trapeze bowing and how should it be corrected

2nd YearHangers, Supports & AnchorsCheck first

A bowed trapeze means the support is overloaded, undersized, or spanning too far. Do not leave the duct hanging on a deflected support; verify the load and upgrade the support method.

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Plain-English answer

If a trapeze bar bows under a large duct, the duct may be physically up but the support detail is telling you it is wrong. Big double-wall duct, heavy gauge duct, lined duct, outdoor duct, or extra added loads can exceed a light support setup.

The recovery is to support the load correctly: stronger strut/channel, closer hanger spacing, additional rods, a center support, or an engineered support detail. The exact rod/channel/anchor choice should follow the approved support schedule and foreman/detailer direction.

Field checklist

Measure the duct size, span between rods, and where the strut is bowing.
Check whether the duct is double-wall, lined, heavy gauge, wet/outdoor, or carrying extra load from another trade.
Look for rods pulling out of plumb, anchors moving, insulation crushed, or joints dipping.
Compare the support setup against the approved hanger/support detail.
Temporarily support or unload the condition if there is a risk of failure.

Ask Foreman

The trapeze under this [duct size/type] is bowing at [location]. I checked the span and added load. Do you want heavier strut, another rod/support point, closer spacing, or an engineered support detail?

Verify before acting

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.

Why is my duct trapeze bowing and how should it be corrected

Plain-English answer

Field checklist

Ask Foreman

Verify before acting

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