The beauty of the simple lap joint is the ease in cutting it, as it is merely two timbers reduced to half of their thickness where they lap over each other. This provides a face-grain-to-face-grain joint with a good amount of connecting surface.
This is an exploded view of a pair of 4″ x 9″ timber frame rafters where they meet at the ridge. They are connected with a half lap joint and peg. The roof pitch is 8/12 and the peg is …