Lock function is a critical component of proper door operation.  Think of your office door; would you consider a lever set that didn’t lock to be adequately secure for this door?  When you take into account the likelihood of an employee on the other side of that door counting the cash from their shift, it’s probably not the best option.  We rely on lever sets multiple times a day without realizing that their vast differences depending on the type of door they are on.

Builders Hardware Manufacturers Association (BHMA) has set the standard across all manufacturers for the numerous lock functions that exist.  This simplifies product comparison across manufacturers, because the function name and F# will be the same.  The F# is a universal part descriptor that manufacturers will include in their product descriptions.

Locking Definitions

Depending on your level of experience with locks and their functions, you may be able to skip these basic definitions. Without a basic knowledge of the lock’s pieces, understanding the varying functions is unnecessarily difficult.

• Latchbolt:  Also referred to as a latch; this is the portion within a lock that is secured into the strike.

• Deadlocking Latchbolt:  There are two components in a deadlocking latchbolt; the latchbolt and the deadlatch.  Upon closing the door, the latchbolt extends into the frame and the deadlatch stays depressed.  When the deadlatch is depressed, the latchbolt can’t be pushed back.  This added security feature means if someone tried to MacGyver their way into a door that had a deadlocking latchbolt by swiping a credit card between the door and frame, their attempt would fail miserably.  Any lock that has a key should have a deadlocking latchbolt.

 

• Lock:  Throughout this post, when I refer to the lock, I am referring to a cylindrical lever.  These same functions apply to cylindrical knobs as well; however, as knobs are not ADA compliant for commercial applications, we won’t discuss knobs.  Check out my cohort Kaitlyn Workman’s post that talks about cylindrical locks.

Now that we’re all on the same page, let’s look at the most common lock functions available for cylindrical (sometimes referred to as bored) locks in today’s market.

Cylindrical Lock Functions

Passage/Closet Latch (F#: F75)

The latchbolt is operated from either side at all times.  This type of lock will never be in a locked state.

Privacy, Bedroom, or Bath Lock (F#: F76)

The latchbolt can be operated from either side of the door.  The lever set is secured from the inside of the door by depressing a pushbutton or other locking device such as a turn.  The lever set can be unlocked by engaging the inside lever, closing the door, or by an emergency release on the outside.

Growing up, my brother probably tried to get rid of all of the paperclips we had in the house.  Ignoring his threats of life and limb, I would maneuver the end of a paperclip into the outside of the doorknob and barge into his room.

Communicating Lock (F#: F78)

Communicating locks have deadlocking latchbolts, and each side is operated by key or other type of locking device.  Both sides must be unlocked for the door to open.  Often times, you will see these on doors that separate adjoining rooms.

Entry Lock (F#: F82)

Entry locks also have deadlocking latchbolts which can be operated from either side of the door. The exception to this rule is if the pushbutton (or other locking device) has been actuated from the INSIDE of the door. The lock can then be released by engaging the lever on the inside of the door, OR by turning the key from the outside. Unlike a privacy lock, closing the door will not unlock the door.

Classroom Lock (F#: F84)

As the name describes, these locks are most often utilized on classroom applications.  They have deadlocking latchbolts, and unless the outside has been locked by key, they are operated by either side of the door.  When the outside is locked, the latchbolt is operated by either engaging the inside lever, or by key from the outside.

Classroom locks cannot be secured from the inside of the door, which is why lock manufacturers are developing new locks that operate much like classroom locks with the addition of a lockdown option.  The goal is to allow teachers (and only teachers) to lock the door in an emergency situation without having to step into the hallway and harm’s way.

Storeroom or Closet Lock (F#: F86)

Storeroom locks have a lever on both sides, but the outside is stationary and cannot be moved.  From the outside, the deadlatch is operated with a key.  Inside, simply engaging the lever will unlock the door. Don’t worry – despite the movie myth portrayal, you can’t get locked in a storeroom.

Entrance or Storeroom Lock (F#: F81)

Just as the name suggests, this lock is a hybrid of entry and storeroom locks.  Unless the inside has been locked by a pushbutton or other locking device, the deadlocking latchbolt can be operated from either side of the door.  When secured, the latchbolt is operated by key on the outside, or by engaging the lever on the inside.

Unlike the entry lock, turning the inside lever will not unlock the outside – the pushbutton (or other locking device) must be manually released from the inside.  This got me into trouble at my old office – I regularly forgot to release the lock on the inside of my door and locked myself out.  The maintenance man loved me (I’m lying… he hated me).

Corridor Lock (F#: F90)

The corridor lock is similar to the entry lock with the only significant difference being the ability to both unlock and lock the door from the outside.  Unless the outside has been locked by key or the inside has been locked by a pushbutton (other locking device), the deadlocking latchbolt can be operated from either side of the door.  The outside is unlocked by key, and the inside can be unlocked by engaging the inside lever or by simply closing the door.

Hotel Guest Room Lock (F#: F93)

These locks are used on hotel rooms, dormitories, and apartment entrance doors.  The deadlocking latchbolt can always be operated from the inside by engaging the lever.  Similar to the storeroom lock, the outside lever is stationary and cannot be moved.  The latchbolt can be operated from the outside by key unless the pushbutton (or other locking device) has been secured from the inside, in which case an emergency key must be used.  When the door has been locked from the inside, there is an indicator visible from the outside of the door showing that the room is occupied.

While this is far from an all-encompassing list of lock functions on the market, it covers the most common.  If you have any questions or want to learn more about the other lock functions, let us know in the comments.  Be on the lookout for a future post defining the varying mortise lock functions.
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