tenoned

A tenoned joint is one where a projecting rectangular tongue, called a tenon, has been cut from the end or edge of one piece of wood and fitted into a matching rectangular recess, called a mortise, cut into another piece. The tenon slides into the mortise and is typically glued and sometimes pinned or wedged to create a strong, rigid connection that resists pulling apart and shearing forces.

Tenoned work appears across interior and structural carpentry. Mortise and tenon joints are standard in furniture frames, where they join rails (horizontal members) to legs and stiles (vertical members). In building carpentry, tenons connect timber beams at intersections. A through tenon passes completely through the mortise piece and protrudes on the far side, where it may be wedged or pinned flush; a blind tenon stops short of breaking through. The tenon itself is typically one third to one half the thickness of the stock from which it is cut, and its length usually matches the thickness of the piece it enters.

The strength of a tenoned joint depends on glue surface area, grain direction, and the precision of the fit. Loose tenons (separate pieces of wood that fit into mortises in both joining members) offer flexibility in design and easier layout on machinery. Multiple tenons on a single joint, such as stub tenons or haunched tenons (where a tenon is reduced in height near its base), distribute stress and prevent twisting.

Why tenons prevail in solid wood joinery

Tenons mechanically lock two pieces of wood together in ways that screws and nails do not. The glued surface area makes the joint stronger in tension and lateral movement than fasteners alone could achieve. Unlike through-bolts or metal brackets, tenoned joints remain invisible and are therefore preferred in visible cabinetry and fine furniture. The straight sides of a mortise and tenon also provide positive alignment during assembly, reducing reliance on clamps to hold parts square.

The main failure mode of a tenoned joint is wood movement across the grain, which can cause the joint to open or the tenon to split if both the mortise and tenon are rigidly glued along their full length. Woodworkers sometimes leave the ends of mortises slightly proud or undercut the tenon shoulders to allow for this movement. Poorly fitted joints, with large gaps or a tenon too thick or too thin, lose mechanical engagement and will fail under load or racking stress.