Find the entry path and protect the system before sealing the first visible wet joint. Check temporary openings, louver and hood orientation, flashing interfaces, curb or plenum details, sealant condition, drain paths, and water carried from another trade or higher roof area.
Water is entering this rooftop duct/plenum. I traced the wet area past the nearest joint and checked the temporary cap, louver, curb, and roof interface. Do you want the system opened for a full water-path inspection before the exterior repair is made?
Watch out
Do not trap water inside the assembly by sealing over wet insulation or blocking a designed drain path.
Check
Document where water is first visible and where it may be entering upstream.
Inspect insulation and liner for wet material that may require replacement.
Verify the approved weatherproofing responsibility and repair detail.
Say this to your foreman
Water is entering this rooftop duct/plenum. I traced the wet area past the nearest joint and checked the temporary cap, louver, curb, and roof interface. Do you want the system opened for a full water-path inspection before the exterior repair is made?