Hello - our TV room was once a porch and then became an enclose room. The roof is is tar and is in good condition. There are two gutters that drain onto the roof of which I've added some downspout extensions to bring the water much closer to the gutter drain at the edge of the roof. I also have a skylight which I know I need to divert as much water from as possible.

Is there an easy and safe way to have the downspout extensions attach to the flat roof? I wouldn't think you want to nail anything to the roof. Also, should I have the end of the downspout flow into a splash guard first and then let is flow into gutter?

Thank you.