lapped dovetail joint

The Lapped Dovetail Joint is a splicing joint that combines the classic lap joint with a dovetail formation in the upper lap. The connection uses the principle of rigid interlocking without additional wood connectors.
The Lapped Dovetail Joint belongs to the family of lap, butt, and dovetail joints. As an I-joint, it shows relationship with simple lap joints and other dovetail connections. Similar principles can be found in Japanese Ari connections and European tenon laps.
The connection is based on a classic lap joint in I-geometry along one axis. The lower lap is executed as a classic lap joint with lap and recess. The upper lap is extended by a dovetail formation that engages with a corresponding dovetail recess. The tapered shape of the dovetail prevents withdrawal in the longitudinal direction.
The additional dovetail formation enables the connection to absorb forces in X- and Y-directions in addition to normal compression forces. The tapered shape of the dovetail makes the connection tension-stable, unlike the simple lap joint. The positive-locking system functions without additional wood connectors such as wedges or dowels.
The connection requires precise craftsmanship, as the dovetail geometry must fit exactly. Imprecise workmanship can cause stresses in the wood.
The lap joint provides large-area contact and even load transfer. The dovetail formation prevents the connection from pulling apart and provides additional stiffness in multiple directions.
The Lapped Dovetail Joint is traditionally used in sills in wall construction, plates, as well as ceiling beams and joists in floor and ceiling constructions. The connection is suitable for highly loaded longitudinal joints where both compression and tension forces may occur.
Manufacturing is carried out using traditional craftsmanship techniques. First, the classic lap joint is marked and chiseled out. Then the dovetail geometry is worked out in the upper lap and the matching recess is made in the counterpart. The connection requires precise fitting work.
The connection can be executed in various dimensions, with the proportions of the dovetail geometry being adapted to the wood thickness.