Idea for terrace covering on garage roof - roofing felt

Exaggeratedly depicted, it looks like the photo. Does a slope of about 2% (4m length) really have such a drastic effect?

Does a slope of about 2% (4m length) really have such a drastic effect?

Nope.

2% over 4m is 8cm.

The slope in the sketch is probably 20-25% (does anyone have a set square? )

I need to follow up here.... Do you maybe have an idea how I can best attach the pedestals to the welding sheets? Screwing is not possible, as otherwise the roof will leak. I was thinking of gluing.... Anyone have an idea for a good and suitable adhesive?