"key will unlock the door" vs "key will *open* the door, but not unlock"

Question

Can anyone help me with terminology to describe two different types of functioning in a door lock. (Please note, I am not talking about a lock that is broken.)

My front door and my back door both have regular old fashioned doorknobs which take a regular old fashioned key. No fancy computerized digital button pushing, no "smart-lock", etc...

When you come in the back door, twisting the key in the lock unlocks it, and then you come inside. If you close the door subsequently, it stays unlocked until you deliberately lock it again.

However, when you come in the front door, the key opens the door, but does not unlock it. The door remains locked until you deliberately unlock it from the inside (with the little twist-button). I feel this makes it much easier to lock yourself out of the house.

I think, but not 100% positive, that both of these locks are made by Schlage. I need to buy a new exterior doorknob, and I would like to get the kind that unlocks when you turn the key in the lock (like my current back door).

I don't even know how to ask for this at the hardware store because I don't know what those 2 different types of locks are called. I cannot seem to get any answers from internet because all I get are helpful suggestions for dealing with a lock that isn't functioning the way it is supposed to.

Answer 1

Lock functions (as applied to your question)

What you're discussing is called a lockset or latchset's function. There are five functions that are considered "basic" in the world of doors and hardware (entry, storeroom, classroom, passage, and privacy), but we only need to deal with two functions for this, namely entry and one of its variations, corridor (which can be seen as a hybrid of entry and privacy).

The entry function is what you have on your front door, according to this article, where you can open the door (retract the latchbolt) with the key from the outside, but need to use the inside button/knob to unlock the door, and it does not unlock when closed. What you have on your back door, though, is the corridor version, which is unlocked but not unlatched by the outside key, and has its inside handle unlocked automatically when the door is closed.

Answer 2

Not an answer to the exact question, but a recommendation based on my knowledge of locks and personal experience:

The only reasonably secure locks are deadbolts.

The "doorknob locks" are nearly useless for providing real security. They are fine for bathrooms & bedrooms to prevent visitors at inappropriate times, but they are useless for preventing criminals from getting in.

Install a deadbolt on each door (front and back). Key them the same for convenience. Then either replace the doorknobs with doorknobs that do not lock at all (to avoid accidental lockouts) or disable/remove the locking mechanism.

The deadbolts should be single cylinder (key required on only the outside) in order to be safe in a fire - you don't want to have to find a key to get out of the house in an emergency.