A tusk tenon is a traditional timber-framing joint in which a projecting tenon passes entirely through a mortised beam and is locked in place by a removable wooden wedge, or “tusk.” This design provides a secure mechanical connection that can withstand heavy loads while still allowing for disassembly when maintenance or replacement of members is required.
In practice, tusk tenons are most commonly found in heavy timber construction such as barn frames, post-and-beam homes, and commercial timber structures. The through-tenon extends flush or slightly proud of the outer surface, and the tusk wedge is driven into a slot cut in the tenon to draw the joint tight. Unlike a blind mortise-and-tenon, which remains hidden and permanent, the tusk tenon’s removable wedge makes it ideal where future access or adjustment is anticipated. In residential applications, you might see smaller-scale tusk joints on exposed beams for aesthetic appeal, whereas commercial or agricultural buildings rely on larger tusk tenons for structural robustness and ease of repair.
As an inspector, I might find them during the exterior walk-around. I recommend inspecting the east-facing ridge beam’s tusk tenon at the gable end for proper wedge seating and tightening the tusk wedge if any movement is detected to maintain the beam’s structural alignment.