The exact method you use for attaching your patio roof will depend on the structural elements of your home. However, one common method used is to attach the roof to the facia board. Then reinforcing the facia to the beams in the roof.
Doing this provides structural support and strength to the home while also placing the patio roof at a lower level to the home’s roof. That way, water on the roof flows downward and away from the home and doesn’t become trapped between the house roof and the patio cover.