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.
Since the simple lap joint is not the strongest of all the scarf type joints, this under squinted half lap joint is beefed up with the slight backward angle on the vertical surfaces- that increases the tension in the joint.
Like all other timber frame joints, this is secured further with hardwood pegs or structural screws.
