Hello ATC,

"Shed Dormer" common rafter systems today are typically (my experience grant you) "let in" with a simple housing and instead of a trunnel attachment (if any in many historic cases) they are attacked with a structural lang/screw such as produced/spec'd by Simpson, GRK, et al.

These are the fastest joinery modalities usually and easiest to place "in situ." there are others that also have housings, toggles, leggings, and even "tusk tenon" systems, as well as "wedge blind dovetails," half doves, lap joints, etc.

Regards,

j