Static field route #18929

What do I do when rooftop duct is holding water on top?

Equipment Connections: RTU, AHU, VAV, Fans & Louvers🟨 CHECK FIRSTV189 answer-gap expansion

📖 Verified core answer

Outdoor duct should not become a pond. If water is standing on top, check panel pitch/cross-break, insulation/weather wrap, support sag, and approved roof-duct detail before it rots or leaks.

Open in Field Rescue Open category

Field verification checklist

Locate the ponding area and whether the duct top is sagging or oil-canning.
Check support elevations, roof slope, top-panel shape, and insulation/weather membrane condition.
Look for open seams, failed tape/mastic, fasteners, or water entry points.
Check whether a pitched cap or shop-fabricated weather hood is required.
Coordinate with roofer/foreman before cutting or rewrapping roof duct.

Ask foreman

The rooftop duct at [location] is holding water on top. I checked support elevation, top panel shape, and wrap condition. Do you want a pitched cap/support correction/weatherproofing repair per detail?

Text to foreman

Route options

AMake the field correction only if it is within your assignment and the approved method.

BHold and document the condition if the fix affects airflow, access, life safety, pressure class, rated assemblies, equipment, or another trade.

CBring the foreman/detailer the location, what you checked, and what decision you need before cover, startup, or rework.

Do not do this

Do not ignore standing water on rooftop duct because “it is outside anyway.”

Why this matters

Ponding water can damage the duct, insulation, roof membrane details, and eventually leak into the building.

Verification basis

Approved drawings/specs, project coordination drawings, manufacturer instructions/submittals, shop standards, foreman/detailer direction, employer policy, and AHJ/code requirements.