Mortise lock

The two main parts of a mortise lock. Left: the lock body, installed in the thickness of a door. This one has two bolts: a sprung latch at the top, and a locking bolt at the bottom. Right: the box keep, installed in the door jamb.

A mortise lock (also mortice lock in British English) is one that requires a pocket—the mortise—to be cut into the door or piece of furniture into which the lock is to be fitted. In most parts of the world, mortise locks are generally found on older buildings constructed before the advent of bored cylindrical locks, but they have recently become more common in commercial and upmarket residential construction in the United States. They are widely used on all ages of domestic properties in the United Kingdom and Argentina.

The term “mortise” comes from the Latin root “mortuus” meaning to die because 17th century judges would sentence the harshest criminals to life in ‘mortuus obituatorium” prison cells, where the door was known to be secured by the most robust locks that were impossible for any attempts by the convicts’ friends to break him out.[citation needed]

The parts included in the typical mortise lock installation are the lock body (the part installed inside the mortise cut-out in the door); the lock trim (which may be selected from any number of designs of doorknobs, levers, handle sets and pulls); a strike plate, or a box keep, which lines the hole in the frame into which the bolt fits; and the keyed cylinder which operates the locking/unlocking function of the lock body. However, in the United Kingdom, and most other countries, mortise locks on dwellings do not use cylinders, but have lever mechanisms.

The installation of a mortise lock cannot generally be undertaken by the average homeowner since it is labor intensive and requires a working knowledge of basic woodworking tools and methods. Many installation specialists use a mortising jig which makes precise cutting of the pocket a simple operation, but the subsequent installation of the external trim can still prove problematic if the installer is inexperienced.

Although the installation of a mortise lock actually weakens the structure of the typical timber door, it is stronger and more versatile than a bored cylindrical lock, both in external trim, and functionality. Whereas the latter mechanism lacks the architecture required for ornate and solid-cast knobs and levers, the mortise lock can accommodate a heavier return spring and a more solid internal mechanism, making its use possible. Furthermore, a mortise lock typically accepts a wide range of other manufacturers' cylinders and accessories, allowing architectural conformity with lock hardware already on site.

Some of the most common manufacturers of mortise locks in the United States are Arrow, Baldwin, Best, Corbin Russwin, Emtek, Falcon, Schlage, and Sargent. Also, many European manufacturers whose products had been restricted to "designer" installations have recently gained wider acceptance and use.

Mortise Lock standards: There are several different standards for mortice locks in use, the most common is:

British Standard (small): Faceplate length: 152.5mm (6 inches) Backset:44.5mm (1¾ inches) C/C(lever lock): 57mm (2¼ inches). C/C(bathroom mortise lock): 57mm(2¼ inches). Used in internal doors.

British standard (large), BS3621: Faceplate length: 176mm (7 inches). Backset: 57mm (2¼ inches). C/C(lever lock): 57mm (2¼ inches). C/C(cylinder lock): 45mm (≈ 1¾ inches). Used in entrance doors.

American standard, ANSI A156.13, ML9000-series: Faceplate length: 203mm (8 inches). Backset: 70mm (2¾ inches) . Used in entrance doors.

Scandinavian standard (small), SS 817382, 20-series: Faceplate length: 150mm. Backset: 45mm. C/C(lever lock): 72mm. C/C(bathroom mortise lock): 72mm. C/C(cylinder lock): 68mm. Used in internal doors.

Scandinavian standard (large), SS 817383, Modular Lock: Faceplate length: 225mm. Backset: 50mm. C/C(cylinder lock): 103.5mm/105mm. C/C(lever lock): 104mm Used in entrance doors.

German standard, DIN 18 251: Faceplate length: 235mm. Backset: 55mm. C/C(lever lock): 72mm. C/C(cylinder lock): 72mm. C/C(bathroom mortise lock): 78mm. Used in entrance doors and internal doors.

Italian standard: Faceplate length: 240mm. Backset: 35mm/40mm/50mm/55mm. C/C(lever lock): 92mm. C/C(cylinder lock): 88mm C/C(bathroom mortise lock): 92mm. Used in entrance doors and internal doors.

Older standards: These standards are no longer in use in new doors, but replacement locks are still being made.

Norwegian standard (large): Faceplate length: 210mm. Backset: 60mm(lever lock)/55mm(cylinder lock). C/C(lever lock): 72mm. C/C(cylinder lock): 95.5mm. C/C(bathroom mortise lock): 72mm.

Norwegian standard (small), 22-series: Faceplate length: 157mm. Backset: 55mm. C/C(lever lock): 72mm. C/C(bathroom mortise lock): 72mm. C/C(cylinder lock): 68mm.

Swedish standard (small): Faceplate length: 215mm(earlier)/205mm(later). Backset: 45mm. C/C(lever lock): 72mm.

Danish standard: Faceplate length: 230mm. Backset: 57mm(lever lock)/60mm(cylinder lock). C/C(lever lock): 72mm. C/C(cylinder lock): 72mm.


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Mortise lock — Lock Lock, n. [AS. loc inclosure, an inclosed place, the fastening of a door, fr. l[=u]can to lock, fasten; akin to OS. l[=u]kan (in comp.), D. luiken, OHG. l[=u]hhan, Icel. l[=u]ka, Goth. l[=u]kan (in comp.); cf. Skr. ruj to break. Cf.… …   The Collaborative International Dictionary of English

  • Mortise lock — Mortise Mor tise, n. [F. mortaise; cf. Sp. mortaja, Ar. murtazz fixed, or W. mortais, Ir. mortis, moirtis, Gael. moirteis.] A cavity cut into a piece of timber, or other material, to receive something (as the end of another piece) made to fit it …   The Collaborative International Dictionary of English

  • mortise lock — n BrE [Date: 1700 1800; Origin: mortise hole made for a part to fit into (14 21 centuries), from Old French, probably from Arabic murtaj locked ] a strong lock that fits into a hole cut in the edge of a door American Equivalent: dead bolt …   Dictionary of contemporary English

  • mortise lock — ► NOUN ▪ a lock set into the framework of a door in a recess or mortise …   English terms dictionary

  • mortise lock — mortise ,lock noun count a strong lock that fits into a hole cut into the frame around a door …   Usage of the words and phrases in modern English

  • mortise lock — noun : a door lock inserted in a mortise * * * (or Brit mortice lock) noun, pl ⋯ locks [count] chiefly Brit : ↑dead bolt * * * ˈmortise lock f9 [mortise lock mortise locks] …   Useful english dictionary

  • mortise lock — UK / US noun [countable] Word forms mortise lock : singular mortise lock plural mortise locks a strong lock that fits into a hole cut into the frame around a door …   English dictionary

  • mortise lock — mor′tise lock n. bui a lock housed within a mortise in a door, so that the lock mechanism is covered on both sides • Etymology: 1770–80 …   From formal English to slang

  • mortise lock — a lock housed within a mortise in a door or the like, so that the lock mechanism is covered on both sides. [1770 80] * * * …   Universalium

  • mortise lock — noun a lock set within the body of a door in a recess or mortise, as opposed to one attached to the door surface …   English new terms dictionary


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.