Birdsmouth joinery takes a special router bit designed for 8 sided pieces (you can also purchase a router bit for 6 sided pieces). Using some glass I had lying around and a glass cutting tool, ...

Learn how to frame rafters, cut perfect birdsmouth joints, and install sturdy plywood decking for a solid, long-lasting roof. Andrew Thron Improvements. Birdsmouth Cuts & Roof Framing Explained.