half lap joint with stub tenon

The tenon lap joint represents a modification of the classical half lap joint. It belongs to the family of tenon and butt joints. As an I-joint, it shows kinship with the dovetailed lap joint and other combined longitudinal connections. The connection unites the half lap joint with the tenon connection in one system.
The lower lap is executed as a classical half lap joint with lap surface and housing. The upper lap is extended by a tenon that engages with a corresponding mortise in the mating piece. This combination of lap and tenon connection creates a multi-dimensional anchorage.
The combination of lap and tenon enables improved force transmission compared to the simple half lap joint. The tenon component prevents sliding in the longitudinal direction, while the lap provides large-scale load transmission. The connection functions without additional wooden fasteners such as wedges or dowels.
The connection requires precise craftsmanship as both the lap surfaces and the tenon must fit exactly. Poor workmanship can create stress concentrations in the timber. The cross-sectional weakening is greater than with pure lap connections due to the tenon component.
The tenon lap joint provides a rigid connection with good positional security.
The tenon lap joint is traditionally used in purlins in roof constructions, sills in wall constructions, and wall plates. The connection finds application in ceiling joists and beams in floor and ceiling constructions. It is particularly suitable for heavily loaded longitudinal joints where both positional security and force transmission are important.
The connection can be executed in various proportions, with the dimensions of lap and tenon adapted to timber thickness and forces to be transmitted. Variations include different tenon forms and thicknesses according to application requirements.