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.
Do not ignore standing water on rooftop duct because “it is outside anyway.”
Check
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.
Steps
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.
Say this to your 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?