Mortise
A rectangular cavity cut into wood to receive a tenon, hinge or lock body.
Quick Answer
A mortise is a recess cut into a piece of wood or metal to receive another part. In joinery it is the socket for a tenon. In door hardware, a mortise lockset has a lock body that fits into a pocket cut in the door edge. The mortise has no unit of its own and affects door prep and labor.
The Full Picture
A mortise is a cavity, usually rectangular, cut into a member so another part can fit into it. The matching part in joinery is the tenon, and the mortise-and-tenon joint is a long-standing way to connect rails, stiles and frames in doors, windows, stair parts and cabinets. In hardware the same word describes a pocket cut into the edge of a door that holds a lock body or a hinge leaf. In estimating, the word comes up in two places: joinery in millwork and cabinetry, and mortise locksets in door hardware.
A mortise lockset is a lock whose case is set into a mortise in the door edge, in contrast to a cylindrical lockset, which is installed through bored holes. Mortise locks are common on commercial and institutional doors and are built by hardware manufacturers to performance standards. The Builders Hardware Manufacturers Association says it develops ANSI performance standards for locks and other builders hardware. The hardware schedule in the specification lists which doors take which function, and it commonly sets the preparation, including whether the door is prepared at the factory or in the field.
A mortise itself has no takeoff unit. It affects the estimate through what is counted. For hardware, the count is each: the number of mortise locksets from the door and hardware schedules, with hinges, closers and trim counted separately. The mortise prep is either included in a factory door price or added as a labor item for field prep. For joinery, the mortise and tenon joints are part of the shop's labor in a millwork price rather than a quantity, and they signal a higher-grade, labor-heavier item than a simple butt joint.
Mistakes usually come from the mismatch of door and hardware. A mortise lockset ordered for a door that was prepped for a cylindrical lock means rework or a replacement door. Hollow metal and wood doors are prepared differently, and the hardware set may not match the door schedule. Estimators should reconcile the door schedule with the hardware schedule before pricing, and note where preps are by the door supplier.
Real Examples
Common Misconceptions
People assume: A mortise lock and a cylindrical lock are interchangeable.
Actually: They need different door preparation. A mortise lock needs a pocket in the door edge, while a cylindrical lock uses bored holes.
People assume: The mortise is a line item in the takeoff.
Actually: It is a feature, not a unit. Count the lockset or the door, and carry the prep as part of it or as a labor add.
People assume: Mortise-and-tenon joints are only for antique work.
Actually: They are still used in doors, windows, frames and stair parts where a strong joint is wanted, and they raise shop labor.
Frequently Asked Questions
What is a mortise in construction?
A mortise is a cavity cut into wood or metal to receive another part, such as a tenon, a hinge or a lock body. The term is used in joinery, doors and hardware.
What is a mortise lockset?
It is a lock with a rectangular case that is set into a pocket cut in the edge of a door. It is common on commercial and institutional doors, and the door must be prepared for it.
What is the difference between a mortise and a tenon?
The mortise is the socket, and the tenon is the projecting part that fits into it. Together they make the mortise-and-tenon joint.
How does a mortise affect an estimate?
It affects door preparation, hardware choice and shop labor. The count is of doors and locksets, and the prep is either in the door price or a labor item.