I am a renter, so I cannot change the locks or drill an additional deadbolt. I came across August Smart Lock today (https://www.amazon.com/August-Smart-Lock-Pro-generation/dp/B0765LFNM7), which sits on top of the handle of the existing deadbolt. I don't need (or want) any smart functionality, however, a device to lock the existing deadbolt from being turned with a key would be ideal.

Are there any purpose-built solutions for this? If not, any other contraptions I could build?

Thank you!

  • Have you asked your landlord about just changing the locks for you? Back when I was a landlord I had these quick-change locks on all my apartments, so switching out cylinders only took me like 2 minutes tops. He may have the same thing. Commented Jul 22, 2019 at 18:21
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    Under most rental agreements, such functionality (blocking the key) would be against the terms of your lease. The landlord and tenant both have rights, and both emergency and (generally with notice to the tenenat) non-emergency access for the landlord is one of those rights. You could get yourself evicted for attempting to block the landlord's access.
    – Ecnerwal
    Commented Jul 22, 2019 at 18:22
  • @EricPetroelje They will, while they retain the key for emergency access.
    – user25400
    Commented Jul 22, 2019 at 18:25
  • @Encerwall - sounds like the solution he is suggesting here would only work when he was actually at home (after all, if he used it when he wasn't home, he wouldn't be able to get into the place himself). So this feels similar to a the chain-type safety lock that you see on many hotel rooms which would probably be OK legally. Commented Jul 22, 2019 at 18:25
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    I have an august deadbolt, and they do not stop the outside key from working.
    – JPhi1618
    Commented Jul 22, 2019 at 18:33

2 Answers 2


I don't think that gadget does that. It certainly will allow you to override with an actual key.

Anyway, the thing you are looking for is a gadget that secures your door absolutely from the inside so nobody can unlock it. That is not what a deadbolt does. Deadbolts are designed to do that and also let people with keys through - that is the entire point of a "key-based" security system.

Now, either you have a seriously misplaced expectation of how door locks are supposed to work... or you have some sort of unique, special security problem that makes keys ineffective. The answer to the second problem is "Try not to allow that to happen, and fix it immediately when it does."

That means if you lose control of your keys, change the keys ASAP so that the random or hostile person's keys no longer work.

Now you say you have a landlord. It really sounds like you're trying to homebrew this without getting the landlord involved. That's a mistake. First, you have a legal obligation to tell him you lost control of a key. Second, he is just as interested in the apartment's security as you are, because someone hostile to you is a direct threat to the apartment - the landlord fears kicked out drywall, smashed pipes to cause flooding, stolen appliances -- an angry guy can do a lot of damage to an apartment, way more than your deposit will ever cover. And that's on the landlord! (Well the bully will do it because it's on you legally, but landlords generally assume you'll be uncollectable.)

So get your landlord "in the loop" here.

  • I have not compromised the keys in any way, shape, or form. It is simply the fact that my landlord holds a copy of the key and I do not want maintenance walking in while I am sleeping.
    – user25400
    Commented Jul 23, 2019 at 16:16
  • @PizzaEater it's been a long time since I've rented, but usually the landlord only comes in at night when you've called needing an emergency repair. If you work at night and sleep during the day, you need to communicate with your landlord so he knows your hours and will be most likely willing to work around your schedule (remember, he may have to pay employees/contractors to work around your day-time sleep schedule, so you may have to be a bit flexible, too). If your landlord is in the habit of wandering in unannounced in the middle of the night, you may want to look for a new place.
    – FreeMan
    Commented Jul 23, 2019 at 17:57
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    @FreeMan The landlord can't enter the unit unannounced, PERIOD. They are supposed to provide advance notice of planned entrances. Only if there's a bona-fide emergency, like a broken pipe in your unit flooding the downstairs unit, but they still have to loudly knock. They cannot simply use a key to slip in unannounced. If OP has a worry of that, they need to find another place to live ASAP. Commented Jul 23, 2019 at 18:01
  • @Harper I was running out of characters for my comment. Also, it been a very long time since I rented. Thanks for that reminder!
    – FreeMan
    Commented Jul 23, 2019 at 18:08

This image is of a commercial product that you can buy cheaply, but you can make something on your own that performs the same task if you want. Basically, you can wrap a strap around the thumb turn of the deadbolt and tie that strap to your door knob:

enter image description here

Item on Amazon

The strap has a big mechanical advantage over the small amount of torque a key can apply so they are pretty effective.

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