Why is shower or locker exhaust leaking water through spiral duct seams?

Field answer

Warm humid exhaust can condense when the pipe skin is cold. Water then follows seams and pinholes until it finds drywall.

Check whether the run is pitched, insulated, sealed, and routed correctly. Dry the area, repair leaks, add approved vapor-barrier insulation or condensation control, and confirm the moisture source is handled.

What to check first

• Identify humid source: shower, locker, kitchen, laundry, or exhaust.
• Check cold-space exposure and missing insulation.
• Look for pitch/backfall and low points.
• Seal seams with approved moisture-resistant method.
• Wrap with approved vapor barrier/insulation where required.

Why it matters

Condensation can damage ceilings, cause mold complaints, and corrode duct from the inside out.

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Final direction belongs to the foreman, approved drawings/specs, manufacturer instructions, pressure/material schedule, employer policy, and AHJ/code requirements.