If you have a clog in your roof drain you will need to inspect it first.
Unclog drain from roof.
Steps to unclog a drain from the roof get yourself up on your roof using a ladder that is properly secured remove the vent pipe cap if required inspect the inside of the vent pipe with a bright flashlight grab the debris if you can see it and test your pipes if you can t see the clog grab your.
Here is have a small compressor with a regulator which can control the air pressure so using the regulator i like to keep the pressure at around 30psi.
Depending on the design of your roof and location of the vent setup and cleanup can also be easier than using an indoor drain opening.
Step 3 hose.
Step 2 snake.
Step 5 clean the roof drain.
Roof vents generally don t have gas traps that introduce tight turns so working from your roof might give you easier unobstructed access to the main drain.
Step 1 inspection.
Top 10 ways to unclog your roof drain.
Step 4 pipe brush.
Clear any leaves or debris from around the drain.