I have a 12/12 roof that I need to cut out a rectangular section and add a 5/12 shed roof to add a window. Around here we call it "ditching" I have heard it called a reverse dormer.
I can cut the hole in the roof but CAN NOT figure out how to apply the shed roof that fits in the hole.
Adding a shed roof is pretty hit or miss for me anyway, most of the time it slopes the wrong direction.