What Are Lock Functions?

Published by Latitude Security Solutions Support Team on 23rd Mar 2020

Door locks are designed for a multitude of purposes, which creates a level of complexity when it comes to buying the correct lock for the use case. The following is an excerpt from www.sargentlock.com (ASSA ABLOY) describing lock functions. We added more commentary with each function listing typical use cases.

Before we dive in, let's have a quick vocabulary lesson:

Cylindrical - A lockset (aka door knob) that fits in a round hole in the door, sometime called a bore. Doors in homes have cylindrical locks.

Mortise - A lockset that fits in a rectangular cavity in the door. It may look like a cylindrical lock from the outside, but a much larger faceplate will be visible on the side of the door.

Lever - The handle being turned to open the door is a handle. Most common in commercial environments.

Knob - The handle being turned to open the door is a handle. Most common in residential environments.

Now let's jump into Lock Functions

FUNCTION	TECHNICAL	USE CASES	IMAGE
Storeroom or Closet	Deadlocking latch Latch by lever inside or key outside Outside lever rigid at all times	Prevents being locked inside a room, such as a storeroom or closet. Always unlocked inside. Always locked outside. Requires key override to unlock OR electric strike connected to access control system.
Entrance or Office	Deadlocking latch Latch by either lever unless outside lever is locked by push/turn button in inside lever Push button released by key outside or lever inside Turn button must be released manually Key retracts latch when outside lever is locked	Can lock from inside for privacy. Can unlock from outside with key override. Because the lock is manually managed with a push/turn button, the door can be left in a state (locked or unlocked) unknowingly. This not a proper lock if paring with access control.
Classroom	Deadlocking latch Latch by either lever unless outside lever is locked by key Key in outside lever locks or unlocks outside lever and retracts latch Inside lever always operative	A flexible solution in that the door can be unlocked at all times. The key can be used to put the lock in a locked or unlocked state and in either state the key can be removed. In the locked state, it operates as a storeroom function lock. It is a good alternative to a storeroom function lock if flexibility is required to keep unlocked.
Service Station	Deadlocking latch Latch by either lever unless outside lever is locked by push button in inside lever Key retracts latch when outside lever is locked Push button released by turning inside lever, closing door, or by key in outside lever unless push button is fixed in locked position by turning coin slot in inside lever Slotted inside button must be manually released	If familiar with using a locked door at a service station, then you know what this means. A key used to open. A push button is used on inside to maintain privacy.
Hotel, Dormitory, or Apartment	Deadlocking latch Latch by key outside and lever inside Outside lever always rigid Depressing push button when door is closed shuts out all keys except emergency key and projects visual occupancy indicator in cylinder face Push button released by turning inside lever automatically reactivating all keys and retracting visual occupancy indicator Lock out key fixes push button in locked position, shutting out all keys except emergency Push button fixed by lockout key must be released manually Lock out key provided	Similar to a storeroom function lock, this is always locked on the outside. Only a key will get you in. Furthermore, if the push button on the inside is depressed, it will prevent any key from opening the door. Emergency key can be used. This lock is designed for maximum privacy, while working well with access control systems.
Corridor	Deadlocking latch Latch by either lever unless outside lever is locked by push button inside or key outside Rotating inside lever or closing door releases inside button only, but does not unlock the outside lever is locked by key Key outside locks or unlocks outside lever and also retracts latchbolt when locked	Turning the inside handle will always unlock the push button (it pops out) and keep the door unlocked from the inside only. The key can be used to override the lock to enter, or keep the outside in a locked or unlocked state - see Classroom Function.