Drywall crushes flex duct in a wall cavity

Crushed flex is an airflow restriction, not a finish-detail inconvenience. Pull it out of the pinch point and use an approved rigid/alternate path that fits the wall cavity without choking the branch.

['Flex duct cannot deliver air if the core is flattened, kinked, or smashed behind drywall. A wall that physically crushes the duct is telling you the material/path is wrong.', 'The fix is usually to stop cover, expose the pinch, and change the branch path or material: rigid wall stack, oval/rectangular metal, different boot location, or approved alternate route. Do not fight drywall around a crushed flex and hope air makes it through.']

Flex Duct, Boots, Collars & Grilles 2nd Year YELLOW

Stop if

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.

Check

Crushed flex can create low airflow, noise, comfort complaints, and ugly rework after drywall is finished.

Steps

Confirm where the flex is being pinched and whether drywall/framing is already installed.
Check branch size, diffuser/boot location, and whether rigid wall stack/oval/rectangular duct is specified or approved.
Check for access to replace the crushed section before the wall closes.
Look for excess flex length, tight bends, and strap/crush damage.
Take a photo of the pinch and ask before changing material or route.

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