Understanding The 20+ Lock FunctionsBy Brian Rhodes, Published Mar 27, 2018, 11:33am EDT
While locks can look the same, they may operate in significantly different ways. To make understanding them simpler, widely adopted industry standards define a range of over 20 different lock functions. Understanding them is vital in picking the locks for a job, or else security vulnerabilities or dangers to life/safety can result.
In this note, we look at these crucial codes, and several key points in working with and understanding lock functions:
- Which Codes Describes Functions Based On Locks Type
- Why Lock Functions Are Important To Access Control
- A Chart Of 20+ Lock Functions Defined
- The Three Most Common Commercial Lock Functions
- Classroom Functions In Detail
- How Functions Are Typically Specified
Standardizing Lock Functions
The 'function' or mechanical behavior of a lock, especially a mortise or cylindrical lever lock, should be specified for an opening. These are classified into more than 20 types, using codes developed by door hardware group BHMA.
The relevant standard defining locks functions depends on the type of lock it is:
- ANSI/BHMA A156.2: Applies to Cylindrical (Bored) Pre-Assembled Locks and Latches
- ANSI/BHMA A156.13: Applies to Mortise Locks and Latches
An easy example of different functions in everyday use can be seen when comparing Restroom (Privacy Function) locks (F76/F02 or F19) and Storage Closet (Storeroom Function) locks (F86/F07).
Using the standard function definitions, bathroom locks include the provision to lock from the inside, preserving the privacy of occupants. However, this same feature is applied to storage closets, simply due to the potential of accidentally locking the door shut and preventing access from the outside, trapping children or potentially incapacitated people inside.
Electronic Access Relevance
The integration and behavior of mechanical locksets are important to preserve in electronic access, per Building Occupancy Codes and Access Control Life/Safety Codes. Failing to understand how underlying hardware operates may result in the improper/illegal use of electronic hardware.
For example, if a mortise lock includes a separate deadbolt, an accompanying electric strike may need to be upsized to include more that one latch, or more than one strike may be required. Likewise, if a lock is an E2161/F18 Deadlock function, it is kept locked unless key unlocked from the outside, and simply using a maglock is not enough to release the door when access unlocks it, potentially killing or injure people trying to escape.
20+ Function Codes
These properties of locks are identified by codes, and there are over 20 different functions available.
Before codes were implemented, functions were defined via common labels like 'Passage Functions, or 'Privacy Locks'. However regional and manufacturer variations of those labels are common, and simply identifying these locks by common labels does not guarantee the exact function will be ordered, so using the alphanumeric code is important for clarity.
The ANSI/BHMA Function codes are:
Common Commercial Lock Functions
These are three of the most common applications, and their corresponding lock functions, for security integrators:
- Office Doors: Most office workers want to lock their doors after hours. The F82/F04 function lets an employee push a button on the back of the lock when they leave, pull the door shut to lock it, and ensure it can only be unlocked by key when unattended.
- Server Rooms: For higher security applications, the addition of a deadbolt is useful. The F88/F09 "Entrance" function allows for an additional deadbolt to be thrown by keyed locking from the outside of the door, when IT leaves a main closet. However, when personnel are inside the room, the lever functions like a "Privacy" lock allowing free egress.
- Break Room: The F75/F01 "Passage" function is ideal for areas using doors for environmental isolations (noise/HVAC) but do not necessarily want them lockable. Areas like Break Rooms are common access, and "Passage" locks assure they are not inadvertently or maliciously locked from use.
Other applications, for example, a medical storage closet, F86 is a likely choice because the door is locked all the time and can only be opened by a key. The door automatically locks when the door is shut, which is ideal for securing a closet filled with valuable items. Code F86 also specifies a cylindrical lockset, although if the door was prepped for a mortise lockset, code F07 would provide the same features.
Not All Functions Code Compliant
Certain occupancies outlaw some functions - E2141/F16 "Double Keyed Deadbolt" cannot be used in most group occupancies, while others strictly define required use of others - F93/F15 only on Hotel/Motel doors.
Classroom Functions In Detail
Code F84/F05 is informally called 'Classroom Function', as they are designed to be installed in schools as a potential protection against active shooters or intruders.
These locks always allow occupants out of a classroom regardless if the door is locked or not. However, in order to lock the door, a key must be used on the outside of the room. This orientation has caused some concern in the wake of school shootings because they expose the teacher or class to danger in order to lock the door. Of note, doors lockable from the inside are F82/F04 Office Function locks.
This explains why some products marketed as 'classroom locks' do not specify F84/F05 code compliance because they can be locked from inside the class. While this potentially may be a safer function, it does not meet the formal 'Classroom Function' definition, and special attention is needed to clarify actual operation.
Function Specification Callout
Most commercial-grade hardware makes finding lock function easy - generally, this is listed on cutsheets, and different product SKUs have different functions, even if the base hardware series is the same. Take this example from Schlage:
Finding the right function is straightforward and many distributors will ask you for this information if you do not include it. Getting the right function ordered is important because it is difficult or impossible to change this attribute in the field.
Most residential and light-grade commercial hardware does not specify any function code, and is simply sold as an 'office lock' or 'bathroom lock'. These products are configured in only the most common functions and may not be compliant with codes or specifications as a result.
[Note: This guide was originally published in 2013, but substantially expanded and updated in 2018.]
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