My apartment door unlocked by itself. Can anyone offer an explanation please?

Question

My apartment door unlocked itself.....a wood kind of one with a round door handle that key goes into. I shook it when I was leaving to make sure it was locked then I came home to find it unlocked....twice. Does anyone please have an explanation for how this could have happened?

Call your landlord (assuming "apartment" = rental) and request an immediate lock change. If you own the place, call a locksmith yourself. Don't delay. — Ecnerwal, Apr 29 '21 at 14:17
It was locked when I left (I even shook it) and unlocked and open when I got home — Kate, Apr 29 '21 at 16:38
If you can get someone to "house-sit", you can simply remove the lock-set from the door, and drive it to a reputable locksmith's retail location, and they will re-key it for under $30. The actual work is cheap; the big cost of a locksmith is bringing the truck to your location. — Harper - Reinstate Monica, Apr 29 '21 at 16:47
I would setup a camera to see if anyone is entering and who. If the landlord/maintenance is the one doing it, having it rekeyed won't change anything as they still have the key. Ideally they should notify you before entering, but in cases where someone below you has water coming in from above, they won't always wait for permission if it's a big enough emergency. — rtaft, Apr 29 '21 at 17:08
"How do you find a reliable locksmith" Not Google. Grab a 10-year old telephone book (so you know they've been in business 10 years)... and say you want to bring in lockset to be re-keyed. If they balk at giving their street address, don't be offended - it just means they do outcall only i.e. they work out of their truck and their "home base" is their house. If they ask for your street address then yeah - be offended! They don't need it! — Harper - Reinstate Monica, Apr 29 '21 at 17:13
What do you think the chances of the lock being defective are? It is an old door with old lock (key goes into ball shaped door handle)....I did lock and then shake it before I left though (OCD) — Kate, Apr 29 '21 at 19:47
@Harper-ReinstateMonica Buy a new lock and just replace a core will be cheaper. only one screw hold it. — user263983, Apr 29 '21 at 20:07
Is it possible you didn't actually lock the door when you left? If the door doesn't have a deadbolt it's possible that the door didn't actually lock when you thought it did — mmathis, Apr 29 '21 at 22:05
@Kate no deadbolt in an apartment? Depending on where you live, you may have the right to make your landlord install one. If it's an old in-knob lock, it actually could be defective in some way. Pictures would help a lot! — Aww_Geez, Apr 29 '21 at 22:50
@Kate -- is the deadlatch plunger (the small plunger on the side of the main latchbolt) staying retracted when the door's shut, or is it dropping into the strike hole along with the main latch? — ThreePhaseEel, Apr 29 '21 at 22:50
I know you have lots of feedback right now, but I think posting a picture of the door lock/knob and how it interacts with the door frame could help. In general, the description sounds like a cheap lock. I would recommend getting a second lock some kind like a deadbolt lock. — Giacomo1968, Apr 30 '21 at 20:32
Presumably, if you don't happen to have a 10-year-old telephone book laying around, you could use Google Maps and look for locksmiths with clearly marked physical locations visible on Streetview, like an actual storefront with a sign and lots of locks in the window. — Zach Lipton, Apr 30 '21 at 21:46
Just put a piece of tape on your door every time you go out. If the tape has been folded in between the door and the door frame when you return, it means someone has opened the door while you were away. Easy. — Daniele Testa, May 02 '21 at 12:41
@gerrit I find it unlikely that a door would unlock itself or that someone else would repeatedly unlock it. I find it more plausible that the OP either forgets to lock the door or does not realize they've unlocked it and thinks someone else has. This sort of confusion could be caused by, among other things, CO poisoning. Hence, a CO detector. There's a famous Reddit thread about Post-It notes being left in an apartment, which this question reminded me of. — isanae, May 02 '21 at 20:44
If the latch uses only a spring-loaded bolt, and no "dead bolt", it's possible that the latch is unlocking itself due to rattling and other motions of the door. At the very least the bolt should be the "dead latch" variety, with a pin that runs along the edge of the bolt and, when depressed, prevents the bolt from being pressed in. — Hot Licks, May 02 '21 at 21:42

score 39 · Answer 1 · answered Apr 29 '21 at 13:48

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Either your door lock is defective, or someone is unlocking the door while you are gone (someone with the key, like your landlord, or someone is picking it open).

answered Apr 29 '21 at 13:48

PhilippNagel

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To follow up, there are some things you can do to tell if the door was actually opened or not. Cameras and sensors are available for this, of course. Low tech solutions would be something like placing a very thing string between the door and the frame when you shut the door. Test this out first. If the string moves or is dropped on the floor, it indicates someone has opened the door. Of course you would want to place this away from the lock as to not make it easy to spot when someone unlocks the door. – PhilippNagel Apr 29 '21 at 14:06
I used to unlock my friends apartment (slide credit card) to steal food or play video games in college. He came home from work 3 hours early one night and there were 4 of us eating his chips and playing NHL 94. Buddy looks at him dead eyed without laughing "you got next game broh". Moral of story was we locked the door behind before he caught us... but some doors can't be locked without a key - apartments do this to keep from lock out calls. If your door requires key... wow creepy. If not just get the lock changed. – DMoore Apr 29 '21 at 15:41
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What do you think the chances of the lock being defective are? It is an old door with old lock (key goes into ball shaped door handle)....I did lock and then shake it before I left though (OCD) – Kate Apr 29 '21 at 19:45
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It is possible for the installation to be defective. The latch on our front door will sometimes not "catch" on the strike plate in certain weather conditions. The deadbolt works fine so it's not an issue. If you don't have one, consider getting a quality deadbolt as well. – JS. Apr 29 '21 at 22:48
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@JS The description of this one is that the door is shut and locked when they leave. Then it is unlocked when they return. It seem unlikely that a lock is defective in that way. – Michael Richardson Apr 30 '21 at 13:25
...or they just made a mistake and didn't actually lock the door. I wonder why no one is taking this into consideration, but to me it seems to be by far the most likely explanation. – MaxD Apr 30 '21 at 14:44
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I once lived in an apartment and came home to find a weird stain on my chair. I got a weird feeling, picked up the phone and hit redial. Someone answered and I asked who it was and he said "Jeff". I didn't know anyone named "Jeff". It was really creepy. Get your locks changed. – JimmyJames Apr 30 '21 at 15:47
@MaxD because they said they tested it was locked before they left – PC Luddite May 01 '21 at 12:59
@PCLuddite Sure, but that doesn't mean anything if we are considering a mistake. Maybe they didn't press the handle down far enough, or their memory is mixed up from another day. Could be lots of things. – MaxD May 01 '21 at 22:03
I 100% def locked it. I have OCD and shake every door I lock and the first time it happened I REALLY checked it was locked the next time I was leaving but still came home to find it unlocked and open again. Like I said it is an old door with an old lock that has since been changed but im still freaked out wondering why it happened in the first place. Doesnt appear to be anything taken and there is plenty to take..... – Kate May 02 '21 at 14:07

score 32 · Answer 2 · answered Apr 29 '21 at 23:58

Most likely, someone is entering your home without your permission. That is probably a violation of your local tenant-landlord laws, but there are other actors who may not know about or respect those laws.

There are several ways this can happen. Some sites have really, really, really bad security. This very long video covers most of them in its first 20% or so. (the rest is about door sensors, card keys and other non-applicable stuff).

Previous tenant

Often they don't change the lock after a previous tenant leaves. Sometimes the tenant is shifty, or sometimes they give a copy of the key to someone else who may not realize that tenant has moved on, such as a friend or contractor.

Master keys

In all apartments, it is normal and legal for the landlord to hold a copy of your key. That is so they can do non-destructive entry when necessary.

It's possible to build a lock tumbler set so that two different key cuts (bittings) will both work. So your lock works with key bitting A and B... your neighbor A and C, your next neighbor A and D, etc. You are issued key B. Your neighbor is issued key C, next neighbor key D, etc. The landlord holds onto key A, which opens every apartment, as well as utility closets, roof access etc.

But of course the landlord doesn't do all their own work; that's not even legally allowed (workers must be licensed). They hire out to contractors. The contractors need access, so as a simple expedient, they hand the contractor an "A" key. At this point, the contractor (on purpose or by mistake) could enter an apartment. Legally the landlord is supposed to give you advance notice of such an entry unless it is an emergency... but that's not the contractor's responsibility, they're there to "Git-r-Dun" and get paid. In an emergency they are supposed to notify you that they had in fact entered - however they may stick that on the outside of the door and other tenants or the wind may tear it off.

If a "master key" gets compromised, i.e. if a contractor copies it, security for the site is blown. Now the landlord has the ignominious task of having a locksmith create a new "AA" key bitting, and re-key your door so it works with "AA" and "B", your next door neighbor's to work with "AA" and "C", etc. for every door on the premises. The landlord often won't bother, or won't even know the key is compromised.

You need to report the entries to the landlord, for this reason alone.

Lock Boxes

Because nothing says "peace of mind" like a Chinese lock box clamped to a fence, with your house keys inside.

Lock boxes are lockable boxes with a shackle, typically locked to doorknobs or fences, sometimes bolted to the side of the building. They have a compartment specifically for house keys. Whoever can access the "lock box" has the keys inside.

They're intended for everything from Realtors to Fire Department access to dog walkers for Pete's sake.

Some commercial sites infamously have a whole row of these things, one per contractor or service provider. Who knows what keys are in it? These have exploded in popularity in recent years. It is the classic example of the war between "usability" and "security".

This combines badly with the above, e.g. if the management company is dumb enough to put a master key in one, or if the previous tenant put your key in a lock box for a service they once used, and that lock box is latched to a fence, forgotten and waiting for someone to pick it.

Door "dead latches" and strikes

See 6:50 in that video.

You notice the door's latch is just a ramp on a spring. Nothing keeps someone from dragging something (hook, credit card) across the slot and the ramp will make it retract. UNLESS...

Better door knobs have a feature called a "dead latch". It's a typically half-moon shaped "rod" right next to the latch. If it is pushed in, the latch will not retract! It can only be operated by the knob/key. If your door set doesn't have a "dead latch", it needs one.

However, the dead latch has to operate against something in the door frame. That is called the "strike". If the strike is the wrong shape, or misaligned, the dead latch will fall into the hole in the strike, and it won't do its job.

Other jamb problems could even cause the door to hop off the jamb with the wind, and open, and re-close. If the lock automatically unlocks in that case, it could be the wind!

Talk to your landlord.

Anyway, talk to the landlord about your door concerns. Most landlords have no issue whatsoever with you installing premium door knobs (they are pretty standard and don't involve modification) as long as you pay for it and they get a copy of the key. If warranted, you could even use a premium access-control key such as Schlage Primus or Medeco M3... they can't duplicate it and you'd only give them one, so they won't risk leaving it in a "lock box".

In some EU countries, it's perfectly normal and legal for the tenant to replace the lock cylinder with one of their own, without ever giving a key to the landlord (you just store the original cylinder and put it back when moving out). It's illegal for the landlord to enter the property without prior arrangement with the tenant anyway, and in major emergencies (fire), the emergency responders will just break in by force, no time to search for keys. (Newer apartment buildings might have automatic remote unlocking of all doors when the fire suppression system activates.) — TooTea, Apr 30 '21 at 07:38
"Because nothing says "peace of mind" like a Chinese lock box clamped to a fence, with your house keys inside." It's actually kind of nice, if I ever lose my keys (say at night while out without my phone) I can at least get inside using the master key for the apartment building from the lockbox at the entry for which I know the code because a contractor put it on a sticky note on the lockbox once. :D — Nobody, Apr 30 '21 at 08:45
They now make lock boxes similar to the one you pictured, but electronic, and with a code that can be changed remotely via a phone app, in order to grant temporary access under controlled circumstances. Realtors use this sort of thing all the time to show residences to prospective buyers, but they are available for general use as well. — Darrel Hoffman, Apr 30 '21 at 13:46
To expand a bit on the subject of deadbolts: the kind of lock you describe (keyhole in the knob) is cheap and very poor. It can be opened with a credit card or any piece of stiff plastic that fits between the door and the jamb. A deadbolt prevents this. In some jurisdictions (mine, in the US), deadbolts are required on apartment doors. In addition, cheap locks are manufactured in a small number of patterns to keep costs down, and it is possible that someone is opening your door by mistake with his key. See https://holdersecurity.com/2016/05/18/the-problem-with-mass-produced-door-locks/ — Wastrel, Apr 30 '21 at 14:14
LPL videos show how easy it is to open those boxes without knowing the code. — JDługosz, Apr 30 '21 at 14:51
Wastrel: a knob lock can have a "dead latch" as described in the post; it cannot be shimmed open. — JDługosz, Apr 30 '21 at 14:52
@Wastrel This is one reason why most apartment doors I've seen open inward instead of outward. This way the door jamb prevents any kind of jimmying as you describe. Also prevents using hammer and screwdriver to remove the hinge pins. (Also note that while deadbolts may be required in some jurisdictions, they're actually banned in others, so it's a mixed bag.) — Darrel Hoffman, Apr 30 '21 at 17:52
@Wastrel Yeah, or the apartment manager assigned a tenant the master key by mistake. — Harper - Reinstate Monica, Apr 30 '21 at 18:11
@DarrelHoffman -- it's possible to get latchsets that have a deadbolt-style separate thumbturn/key but still permit single motion egress, but they require a more commercial-style door prep than what you'd find on a cheap door from the big-box store — ThreePhaseEel, May 01 '21 at 01:28
@JDługosz sure, but LPL also shows how easy it is to just pick the door key way directly. As the saying goes: locks are just there to keep honest men honest. — Tim, May 01 '21 at 21:59
@Tim LPL shows how easy it is for LPL to pick a lock. Picking a lock is actually kind of hard, and requires having cultivated both fine motor skills/sensitivity and lots of practice in lockpicking, which requires e.g. lock picks and a vise to hold the practice lock to your workbench. Whereas many lockbox exploits are "jab a piece of metal in the right place". — Harper - Reinstate Monica, May 01 '21 at 22:17
@Harper-ReinstateMonica I think you’re oversimplifying the lockbox attacks: he has a specially cut bit of metal to grab the bar / feel the flat on the wheel. Then you have to carefully find the “gate” of the wheel where it feels set. I’ve tried the lockbox attacks: they’re not a first-time-immediately-in thing. It’s not just “jam a piece of metal in the right place” anymore than “jam a piece of metal in the right place” is a description of picking a key way! — Tim, May 01 '21 at 22:21
And that’s aside from a lockbox being “essentially fine” because insurance (at least most home insurance in the U.K.) covers that. For me, the risk of being locked out by losing a key is much higher than the risk of someone decoding a lockbox to get into a house to steal something covered by insurance! I also suspect most burglars would use the brick-through-window method! — Tim, May 01 '21 at 22:25
re LPL lockboxes, it really is that easy. i don't have any prior lock picking experience and after watching a few LPL videos I am able to open lockboxes and a few other tricks. practiced on two occasions for about an hour each. tools are cheap 10 - 25 USD. — zamnuts, May 01 '21 at 23:10
These have exploded in popularity in recent years, have they really? I would expect that modern commercial sites that need to manage access to varying number of contractors use electronic locks for all access except the master key. Easy to manage who has access to what door, no need for dozens of keys, and no risk of rogue copies having access after their access should have been lifted. (They have their own issues, of course, but it would seem the advantages far outweigh the downsides.) I've only seen lockboxes to manage entry for hotel guests arriving when the reception is closed. — gerrit, May 02 '21 at 21:50

score 6 · Answer 3 · answered Apr 30 '21 at 02:55

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If this has happened more than once, motion sensing game cameras are cheap these days and the comment recommending you put up a camera deserves to be an answer. If someone has entered your place and nothing was stolen, especially repetitively, it might greatly benefit you to know who as it could be inappropriate activity by a landlord or something less OK than that. I'd put up a camera and at most re-key the existing lock so a change is not obvious and you have a good chance of getting video of whatever person attempting to enter one last time.

I had my front door crowbarred open about 10 years ago. Still no idea what if anything they took. Thousands of dollars in recent electronics that could have been hauled out rapidly. Initially my roommate thought a box of loose change had been stolen, but I found it a few years ago after he passed away.

answered Apr 30 '21 at 02:55

K H

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While this is a good idea, it remains secondary to securing the access door. Cameras stop nothing, they simply add extra information after the fact. – Criggie Apr 30 '21 at 09:49
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@Criggie If the problem is someone repeatedly breaking into a home for sinister purposes, a new lock won't guarantee long-term safety; they'll probably just switch tactics. A camera might get them arrested. – user3153372 Apr 30 '21 at 11:14
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Just as an FYI, make sure the camera streams off-site. My neighbor's house got robbed and the thief also made sure to remove the SD card from their security camera. – Machavity Apr 30 '21 at 16:20
@user3153372 lets go with "why not both" as an acceptable set of actions for OP. – Criggie Apr 30 '21 at 23:28
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Yeah the intent of that part is to emphasize the benefit of not changing the look of the lock. Re keying would be easiest, but if it's a recent lock you can probably buy a new set for roughly the same cost or less. Setting up a camera with a net link requires tech skills so a layperson could take some time to get the camera up or be stuck with a monthly fee. I'd go out and buy a game camera the same day and hide it. Especially if the lock is changed and you can put the camera inside, this is likely to be adequate. That said if you have the budget or skill, network cameras are cheap. – K H Apr 30 '21 at 23:43
Not as cheap as putting a piece of tape on the door and see if it's folded when you come back. Thus, someone has opened and closed the door without your knowledge. – Daniele Testa May 02 '21 at 12:42
@DanieleTesta Other than never being 100% sure of your own memory, OP appears to have crossed that bridge. The point of the camera is not to figure out if, but who. The next step may be informing the authorities, who are going to do nothing or worse without a photo and close to nothing with a photo. Close to nothing is still better than nothing or worse. – K H May 02 '21 at 22:53

sevensevens · Answer 4 · 2021-04-30T22:22:15.683

It means someone is breaking into your apartment

It's most likely a handy-man or contractor with some bad intentions. Just google "handy man breaking into apartment". In many cases apartment complexes hire people without a background check.

Immediately call your landlord

Tell them you know your door is locked, but you've come home to an unlocked door twice. Hopefully it's an oversight and the person was supposed to be there. If there were no work orders rekey immediately!

Buy a security camera that can stream to your phone

By a camera that will live stream the apartment and save it offsite. You can set it to alarm when it detects movement. If it is a handy-man, you may have just tipped them off, and they'll be more careful to lock-up behind them.

If it is someone on payroll, the security camera will let you catch them red-handed.

Maybe sleep somewhere else until the new lock is installed

Consider staying at a friend's place. The worst case scenario is a very bad person has you in his sights.

As far as sleeping, simply setting a piece of furniture in front of the door will assure an entry won't be quiet. — Harper - Reinstate Monica, May 01 '21 at 22:20

keshlam · Answer 5 · 2024-03-01T06:31:23.980

I'm sorry to have to ask this, but starting around my own age it becomes relevant: Is there any chance that, despite your confidence, you really did forget to lock the door/shake the handle on the way out?

As locksmiths and landlords will tell you, one of the early signs that memory isn't as good as it once was is that we start noticing things aren't the way we thought we left them, and it's very common for folks to look for someone to blame it on rather than accept that age is catching up with them. "Senior paranoia" is the extreme version of this, but occasionally forgetting a task happens to all of us and it's easy to misremember when it's a task you do almost automatically and can't imagine not doing.

Heck, even a locksmith occasionally leaves his door unlocked by mistake... Or, more embarrassingly, locks himself out with not just the key but the tools on the wrong side of the door. (My solution to that last: a friend has a copy of my key, so I go borrow that. Best lockpick in the world is a copy of the right key. Even if it does give them a chance to laugh at me.)