Two Keys or Not Two Keys?
February 16, 2022 11:44 AM   Subscribe

The hubby and I are getting a security door for our main entry. He wants one single key for both the existing door and the new security door (mostly for convenience). I think two keys, one for each door, would add to our security. Which is best: two keys or one?

We live in an area that is sadly beginning to see more crime, and there have been several burglaries and robberies in the surrounding community. Hubby and I have decided to install a new security door, which we are looking into right now. Yay!

However... he wants one single key for both the main door and the security door, mostly for convenience, which I completely understand.

I think that if our ultimate goal is to increase our security, then two separate keys for each door would make more sense. Let me know if I'm wrong here.

I'm having a hard time coming up with websites and statistics to support either argument, and so I'm turning to the Hive for any information you have one way or another. If having a single key for everything is great, then I'll go along with it! If it's more secure to have separate keys for each door, then I'd love to have something to show to the hubby to inform him as to why this would be a better option.

Any links you want to share are more than welcome!

So which should it be, Hive Mind? Two keys or one? Thanks in advance...
posted by chatelaine to Home & Garden (24 answers total) 1 user marked this as a favorite
I mean, the "two keys" thing only matters if someone gets hold of your keys, right? Who are you theorizing would have access to one key but not the other? Otherwise, if someone's breaking in *without* a copy of your key, it's no more difficult to sneak past two locks with different keys than it is to sneak past two locks with the same key. (I guess there's the very slim chance someone could photograph one of your keys and make a copy from the photo? Maybe I'm missing something obvious!)

Also consider - if it is inconvenient to ensure that both doors are locked (e.g. because of the different keys) it becomes more likely that one of the doors will be left unlocked.
posted by mskyle at 11:51 AM on February 16, 2022 [28 favorites]

Most robberies are not going to be using keys, so I think one key is best.
posted by soelo at 11:53 AM on February 16, 2022 [10 favorites]

Nobody is likely to painstakingly pick the locks to your front entrance, so 2 locks are probably no safer than 1 in that respect.

If one of you has your keyring stolen, then whether it takes 1 key or 2 to get in, the thief will have access.

If you lend keys to someone -- a houseguest, a petsitter, etc. -- you will need to lend them all the keys necessary for entry, whether that's 1 key or 2 keys. So if they or someone they know is going to be dishonest, you're screwed either way.

In sum, I don't really see 2 locks offering much more protection than 1.
posted by Artifice_Eternity at 11:53 AM on February 16, 2022 [4 favorites]

Locks only keep out honest thieves.

Turn the security issue around:
You in an unsafe situation outside of your home (weather, erratic neighbor, etc), and you need to gain entry quickly. Which is going to be more expedient for you: one key or two?
A friend is looking in on your dog or child home alone. Which is going to gain them entry to your home faster in an emergency: one key or two?
Which is easier to store in a hide a key: one key or two?

If I want to commit a property crime, I'll just break your window.
posted by phunniemee at 12:05 PM on February 16, 2022 [26 favorites]

Have you considered a lock with a keypad? The good ones allow you set a temp # so someone (housesitter, tradesperson) can enter when needed. That way, you’d still only have one key.
posted by dbmcd at 12:09 PM on February 16, 2022 [13 favorites]

Another vote for one key. 2 keys only increase security if the keys are always kept separate and even then it's only against attacks on the doors that use keys. if you are worries about picking, somebody still has to pick BOTH locks even if they are keyed identically.

What you want is just to maximize inconvenience for someone using a brute force attack.
posted by Dr. Twist at 12:10 PM on February 16, 2022 [2 favorites]

I think one key is better because there will be circumstances where you’re trying to get your door open carrying something bulky or heavy, and switching keys for the second door will be awkward using only one hand, which will delay you at the door, and that’s a moment of vulnerability.
posted by jamjam at 12:10 PM on February 16, 2022 [3 favorites]

Two keys increases your attack surface. If the ultimate goal is increased security, one key is safer than two. But agreed with everyone else here that locks only keep out honest folks, and you'd be better off spending the cash on bright property lights or other, more effective security measures.
posted by Jairus at 12:12 PM on February 16, 2022 [1 favorite]

Two keys feels more secure because it seems like having two passwords for a computer system — a brute force attack will take twice as long on two passwords as on one.

But home robberies are not like computer systems, and the brute force attack in this case is a crowbar to a door or window — one or two keys doesn't factor into it.
posted by wemayfreeze at 12:18 PM on February 16, 2022 [5 favorites]

When we moved into our house, the locksmith was kind enough to talk us out of buying the special expensive locks, by gesturing silently at the window.

I'm definitely in the camp of "all you're going to accomplish with two keys is inconveniencing yourself, or ending up leaving the inner door unlocked most of the time".
posted by ook at 12:37 PM on February 16, 2022 [8 favorites]

Same key for every external door in your house.
posted by Geckwoistmeinauto at 12:46 PM on February 16, 2022 [6 favorites]

Two keys increases your attack surface.

In this case, how does this work? the doors are in series, not parallel.
posted by Dr. Twist at 1:25 PM on February 16, 2022 [3 favorites]

We did two keys for our apartment, because there were some people (dogwalker, occasional cleaning person) that we wanted to give keys to, but didn't know well enough to assume that if we went on vacation should have full access to our home (we trust them completely, but we don't know who else they have in their lives and whether those people are trustworthy, and that's none of our business).

The reality is that once we had relationships with those people long enough, we never used the second lock anyway, even on vacation, because if something went wrong while we were away (power outage, a neighbor hearing or seeing something strange) and we needed someone to go into our place, those are the people we'd call - so we want them to have access.
posted by Mchelly at 1:37 PM on February 16, 2022 [1 favorite]

One key. Lock pickers still have to pick both locks.
posted by Oyéah at 3:15 PM on February 16, 2022

You may as well upgrade to a smart-lock. :)
posted by kschang at 4:17 PM on February 16, 2022

One key is actually stronger in security terms, I think. Because you're humans, one or both of you will get sick of fishing around for two different keys and stop locking one door or the other.

As others have said, picking two identical locks is not really any easier (maybe marginally, but not enough to matter) than picking two different locks and crowbars don't care either way. Simply having a locked security door will be a huge disincentive because they're harder to brute force than 'normal' doors.
posted by dg at 5:07 PM on February 16, 2022

This would only make sense if you were dedicated to keeping the keys separate (one in your pocket and one in your bag for example.). Otherwise whoever steals your keys is going to end up with both of them anyway.
posted by Tell Me No Lies at 8:21 PM on February 16, 2022

The thing no one seems to have pointed out is that the security door helps prevent someone from just kicking in your door... and that's a lot more likely than someone picking both your locks, anyway.

So getting the added security door is a good thing for that reason - but then, the goal is to make sure it's convenient to always lock both, with a secondary consideration that you can get in quickly yourself if you ever need to.

While you're at it, seriously take into consideration things like lighting, windows/ sliding doors, and cameras. Then assess how you're dealing with your vehicles and packages.

The best way to reduce your odds of being a crime victim is to make it less convenient for a thief... more work, more time, more hassle, greater chance of being interrupted, etc.
posted by stormyteal at 11:14 PM on February 16, 2022

Two keys increases your attack surface.
In this case, how does this work? the doors are in series, not parallel.

I think "attack surface" may have been about the space/time where you're vulnerable to attack while unlocking the door to get in--more time fumbling with your keys.
posted by needs more cowbell at 5:07 AM on February 17, 2022

Best answer: Just beware of the programmable electric battery powered locks.

My building has them. The management comes around and changes the batteries every year when they do an apartment inspection. With the pandemic that didn't happen and a lot of people bailed to their parents' places out in the suburbs, country or out of state so their door locks went unused for months. As a result they didn't see the flashing red warning light on the lock that their batteries were dying. So their locks died while they were not at home. I woke up one night at about 11pm to a cacophony as a locksmith was trying to drill out the lock on a neighbor's unit so they could get in and get some sleep after driving cross-country to return to their apartment. It took about two hours for the locksmith to get in and put in a temporary lock.

Smart locks can become incredibly dumb locks at very inopportune times.
posted by srboisvert at 5:32 AM on February 17, 2022 [4 favorites]

I just have to point out this is a little eponysterical!
posted by Mrs. Rattery at 5:57 AM on February 17, 2022 [4 favorites]

Nobody is picking the locks anyway. They're either using bump keys or breaking windows, both of which are fast, efficient, and # of keys doesn't matter.
posted by liminal_shadows at 6:58 AM on February 17, 2022

There might also be situations where it would be safest for you to be able to enter your home as quickly as possible.
posted by oceano at 11:55 PM on February 17, 2022

Response by poster: You guys sold me 100% on getting one key for all locks! Thank you all so much! The convenience for us does outweigh everything else. The security door we ultimately decided on is an excellent one that we both feel very confident about and we got the lock issue resolved today.

And Mrs. Rattery, that is so great. I meant for my MeFi name to be after the French for "lady of the manor", and the etymology of the term seems... ha ha... lock step... with what you shared. Thanks for the enlightening comment!
posted by chatelaine at 2:45 PM on February 20, 2022 [1 favorite]

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