Interior door locks come in three functions, sorted by who controls the door: a passage latch gives control to nobody, a privacy lock gives it to the person inside, and a keyed lock gives it to whoever holds the key. A passage latch only holds the door shut. A privacy lock locks from inside and has an emergency release outside. A keyed lock needs a key to open from outside.
Passage and privacy: the two functions without a key
A passage latch is the simplest interior function. Turning the knob or lever on either side pulls back the latch bolt, the slanted metal tongue that holds the door in its frame. There is no button and no keyhole. A passage latch keeps a door from drifting open and does nothing more.
A privacy lock looks almost the same from across the room. Up close, the inside knob or lever has a push button or small turn piece that locks the outside handle. The outside has no keyhole, only a small hole or slot. That opening is the emergency release, which lets someone outside open the door if a child locks it or a person inside needs help. On many privacy sets, turning the inside lever also unlocks the door, so nobody gets stuck on their own side.
The emergency release is the whole point of a privacy lock, and it also sets the limit. A privacy lock is a courtesy lock: it tells others the room is in use and stops someone walking in by accident. It will not stop a person who has decided to get in.
The difference between the two non-keyed functions is narrow. A passage latch gives the occupant nothing to lock. A privacy lock lets the occupant lock the door and still lets someone outside open it in an emergency without a key.
Keyed interior locks hand control to the key holder
A keyed interior lock has a cylinder on the outside, the part with the keyhole. Some keyed functions let a button lock the outside handle while a key opens it. Others keep the outside locked at all times, so only a key gets anyone in. On most keyed interior sets, the inside lever still opens the door freely, so the person inside can leave.
Keyed functions belong on doors where someone other than the occupant decides who enters: storage rooms, utility and equipment rooms, offices, file rooms, and any room holding valuables or records.
Choosing a keyed lock also means choosing how keys are managed. Someone has to decide who holds copies, whether rooms share a key, and what happens when a key goes missing. In a home, that might be one spare on a hook. In an office or a building with many keyed doors, a master key system lets each person's key open a set group of doors while one master key opens them all. When a key leaves with a former employee, the cylinder can be rekeyed so the old key stops working. A smart lock is another way to control a door, but the same question of who should get in still applies.
Three questions that sort any interior door
- Does anyone need to lock this door from the inside? If not, a passage latch is usually enough.
- Does anyone need to lock it from the outside, when the room is empty? If so, the door needs a key.
- Must someone always be able to get in, even when it is locked? If that person is a family member helping the occupant, a privacy lock's emergency release covers it. If that person is a manager or owner, they need a key.
A yes to the first question and a no to the second points to privacy. A yes to the second points to keyed, whatever the answer to the first.
Which lock function fits which room?
- Bathroom: privacy, so the occupant can lock it and someone outside can still get in if needed.
- Bedroom: privacy in most homes. Keyed only if the room must be locked when empty and you have decided who holds copies.
- Hall closet: passage, since the door only needs to stay shut.
- Home office: privacy if the goal is quiet. Keyed if it holds records or equipment you want locked while you are out.
- Shared office or back office: keyed, often as part of a master key system in larger workplaces.
- Storage room: keyed, usually with the outside locked at all times.
- Room occupied by a separate tenant: keyed, with a clear decision about who holds keys before the hardware goes on.
The two easy mistakes run in opposite directions. A keyed lock on a bathroom or bedroom where privacy would do adds a key to lose and can shut a person out of their own room. A privacy lock on a room that needs controlled access protects nothing: anyone can open it from outside, and nobody can lock it behind them when they leave.
For help deciding which function goes on which door, call Imperial Locksmith & Security at (917) 500-1145. The company handles commercial door hardware, lock changes and rekeying, and master key systems in Midtown Manhattan and across all five boroughs.
Frequently asked questions
Can I swap a passage lever for a privacy lever without replacing the door?
Swapping a passage lever for a privacy lever usually works on the same door, because sets in the same style often fit the same holes. The two measurements to match are the bore hole, the large round hole through the door face, and the backset, the distance from the door's edge to the center of that hole. Also confirm the privacy button will sit on the side you want to lock from.
If I need a keyed lock on an interior door, should every door in the building use the same key?
Keying every interior door alike is convenient, but anyone holding one key can open every room, and a single lost key affects all of them. A master key system is the usual middle ground: each person carries a key for only the doors they need, and a master key opens the full set. The more people hold keys, the bigger the problem when one goes missing.
Is a privacy lock enough to protect valuables kept in a home office?
A privacy lock is not enough for valuables in a home office. It keeps people from walking in while you work, but anyone outside can open it through the emergency release, and you cannot lock it behind you when you leave. A keyed lock lets you lock the office while you are out. For items of real value, a safe adds protection a door lock alone does not.