Ask a supplier for a lock and you will be asked a question back: what function? The word sounds vague, but in door hardware it is precise. A function is a defined set of behaviors describing what each side of the lock does when the key turns, when the button is pushed, when the door closes, and when someone on the inside wants out. Two locks that look identical can behave completely differently, and the function code is the only reliable way to say which one you want.
Function is a specification term, not a sales term
Functions are defined in the ANSI/BHMA A156 standards and referenced by number in construction documents. Federal master specifications call locks out this way throughout their hardware sets: a passage latch is specified as F01, a keyed privacy lock as F13, a classroom lock as F05, and a storeroom lock as F07. The set lists the function alongside the closer, the strike, and the plates, so the installer receives a behavior, not a brand.
The same standards define the performance the lock has to deliver while behaving that way. ANSI/BHMA A156.2 covers bored and preassembled locks and latches across operational, durability, security and finish tests, so a specification can pair a function with a grade and get both behavior and endurance in one line.
The common functions, in plain language
- Passage. No lock at all. The latch holds the door closed and both levers always retract it. Used on corridor doors, closets, and any opening that needs to latch but never needs to be secured.
- Privacy. Locked from the inside by a button or turn, with an emergency release on the outside that opens with a coin, tool, or emergency key. Bathrooms and single occupancy rooms. It is a do not disturb function, not a security function.
- Office. Locked from the inside by a button or turn and released by key from the outside. The occupant controls their own door, and the inside lever always retracts the latch.
- Storeroom. Outside lever is always locked and a key is required every time. The inside lever always retracts the latch. Nobody can accidentally leave the room unsecured, which is exactly why it suits electrical rooms, IT closets, and supply storage.
- Classroom. The outside lever is locked and unlocked by key from the corridor. The inside lever always retracts the latch. The teacher does not have to step into the hall to change the door’s state at the start and end of the day.
The distinction between storeroom and classroom is the one that trips people up most often. Storeroom is permanently secure; classroom can be left unlocked deliberately. Both keep the egress side free.
Classroom security and lockdown variants
Traditional classroom function has a well known operational weakness: securing the door requires a key from the corridor side. That prompted a family of variants that allow the room to be secured from inside, using a second keyed cylinder on the inside lever, a thumbturn, or an intruder function that locks the outside lever from within while leaving the inside lever free.
These variants raise real questions about who holds the key, how a room is reopened by responders, and how the choice interacts with local requirements. Selection here should involve the AHJ and the district or facility’s own emergency planning, not a catalog page.
Egress stays free regardless of function
Every function described above shares one property: the inside lever always retracts the latch. That is not a coincidence of design, it reflects a foundational code principle that occupants must be able to leave without keys, tools, or special knowledge. Model code adopted at the state level, such as Washington’s building code provisions on doors, gates and turnstiles, permits locks and latches to prevent operation of doors only in narrowly enumerated circumstances, and those exceptions carry their own conditions.
If a proposed hardware arrangement would require a second operation, a key, or a tool to get out, that is the moment to stop and involve the authority having jurisdiction rather than to improvise.
Choosing from how the room is used
Skip the catalog and write a sentence describing the room’s operation. Who needs to get in, who controls the door, and should it ever be possible to leave it unlocked by accident? A room that must never be left open is storeroom. A room whose occupant should control access is office. A room whose door state changes on a schedule is classroom. A room that only needs momentary personal privacy is privacy. A door that only needs to stay shut is passage. Answer the sentence and the function code follows.
