Do not notch or flatten the duct to sneak around a storm drain pipe.
Check
Measure pipe size, elevation, slope, and duct centerline.
Check whether the pipe can move or is fixed by slope/structure.
Confirm insulation and service clearance.
Lay out possible 45° offset path without choking the duct.
Document the clash before modifying the run.
Steps
Measure pipe size, elevation, slope, and duct centerline.
Check whether the pipe can move or is fixed by slope/structure.
Confirm insulation and service clearance.
Lay out possible 45° offset path without choking the duct.
Document the clash before modifying the run.
Say this to your foreman
The storm drain crosses our duct path at [location]. I measured the pipe, slope, and duct elevation. The clean options look like a 45 offset or revised route. Which direction do you want?