beveled lap joint with stub tenons

The beveled lap joint with stub tenons is a longitudinal I-joint where two members are connected through an overlapping lap surface and secured by inserted wooden pins (stub tenons or pegs). The joint combines the overlap of lap surfaces with additional anchorage through tenons, creating a form-fitting connection capable of transmitting both compressive and limited tensile forces.
This joint belongs to the lap joint family and shares similarities with the simple scarf joint and the Japanese daimochi-tsugi (oblique scarf joint with stub tenon). Unlike other longitudinal connections, the lap surface is reinforced with inserted wooden pegs that prevent the members from sliding apart. The beveled execution of the lap surfaces strengthens the anchorage of the connection.
The characteristic geometry consists of two lap surfaces joined at an angle, cutting approximately one-third to half of the member thickness. Mortises are drilled into the overlapping areas, into which wooden pegs are inserted as locks. These pegs penetrate both members and secure the connection against longitudinal displacement. The beveled shoulder supports load transfer and reduces cross-sectional weakening compared to pure tenon joints.
The beveled lap joint with stub tenons enables the extension of members when timber length is limited and offers cost-effective fabrication with traditional tools. The connection is form-fitting and can absorb limited tensile forces. The peg reinforcement prevents the members from pulling apart. However, the notching reduces the load-bearing capacity of both members. The joint is susceptible to shrinkage cracks during moisture fluctuations and requires precise fitting accuracy of the lap surfaces.
Traditionally, this joint is used in structural carpentry for sills, beams, and joist systems. It is employed when members need to be extended and moderate loads must be transferred. In timber-frame construction and historical wall and floor structures, it is frequently encountered. The joint is also suitable for repairing damaged beams, as it allows the replacement of partial sections.
Fabrication is carried out by precisely marking the beveled lap surfaces, accurately sawing the overlapping areas, and cleanly chiseling out the material. Subsequently, the mortises are drilled and the wooden pegs are fitted precisely. The pegs are driven in and can be wedged if necessary. The fitting accuracy of the lap surfaces is crucial for uniform load distribution and the structural integrity of the connection.