All complex assemblies involving multiple trades demand the critical, and constant, focus of supervisors. Where one trade ends and another begins must show continuity. If you do not build redundancy into the system, you are building in risk.
Drip edge metal, valley flashing, dormer, chimney, and kickout flashing are types of roof flashing that shed water away from the connections between roofs, walls, chimneys, and other building assemblies
The IRC is a thick book, but there is relatively little aimed at decks. A few sections have a few sentences dedicated to construction of safe and durable decks.