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How to Lock Someone Out Who Has a Key? – 5 Effective Ways

Fact checked by Teddy B.Miller

how to lock someone out who has a key

Your door and its lock are great devices to keep intruders—or unwanted guests out of your house.

But what would happen if someone has unsolicited possession of your key? It’s terrifying to think they could just enter your property and harm you and your loved ones.

But don’t fret since there are several measures to keep someone with a key from getting in. Follow this guide to defeat terrorizing feeling of getting burglarized and learn how to lock someone out who has a key.

Ways to Lock Someone Out Who Has a Key

It’s impossible to be at ease and sleep soundly when you need to guard your house against possible intruders. But thankfully, you can take action by using these different methods to lock your door if someone has a key.

#1 Rekey your lock


If you need to secure your house and yourself immediately yet effectively, rekeying your lock might be the best possible method to keep someone from unlocking a door. It is a good, quick, and cheap alternative to replacing your lock entirely.

Inside the lock is the lock tumbler with the key pins, which are responsible for restricting other keys from turning the lock open. Pushing the pins upwards, even a little, will stop the tumbler from rotating and opening the lock.

That’s why the lock only opens if the key pins match the key cuts.

Through this method, you can stop a key from working because the key pins are remodified or rearranged; hence, the original (or stolen) key will lose access to the lock.

Follow these steps to rekey your lock:

  • Remove the lock from the door.
  • Disassemble the lock cylinder, make sure you take the clip ring (with a C-shape) from the cylinder lock.
  • Remove the key pins from the lock tumbler.
  • Rearrange, or file the key pins to rekey the lock.
  • See if the tumbler rotates inside the cylinder.
  • Reassemble the lock cylinder and put it back in the door.

If you’re not confident with the task, calling a locksmith is always your go-to solution!

#2 Add a secondary lock

An additional lock to support your primary lock is always a good measure to make your house safe from unwanted guests. Even in normal circumstances, doubling (and even tripling) your external door lock is a must to stop someone from picking your lock.

Regardless if the person can open the primary lock, they still cannot get into your house because you have additional locks installed.

Although this requires you to spend a little more, several door restrictors like a keyhole latch or lockable door chain in your door will give you peace of mind. External door latch padlock even ensures your house safety if you’re outside.

Moreover, installing these locking devices is straightforward and as easy as one-two-three because the installation manual is often included in the package. If not, an online tutorial is your friend!

#3 Block the door shut


Like in movies, you can lock someone out by putting an improvised barricade on your door, which will serve as your door stopper. However, this will only work if the door opens inward.

The chair-blocking method works best to prevent someone from unlocking your bedroom door or external door. This method is also a great course of action if you are in an emergency.

  1. Place the top of the chair’s backrest under the doorknob. Make sure the edge of the chair is resting between the doorknob and the door.
  2. Angle the chair into a slanted position wherein its front feet are not touching the ground. This step is crucial as this will put pressure on the door and stop the person from entering.

You can also use other heavy furniture to block your door, like a fridge, table, and couches.

However compelling, this chair under door knob method has a durability issue and just works temporarily. The intruder might destroy the barricade if they used force.

#4 Stuff the keyhole using a keyhole lock


A keyhole blocker will work best for you if you have a door with a keyhole on both ends of the lock. And just like the name suggests, this device is used to block key from back of the knob and prevent the door key from functioning.

The keyhole lock set comes with a keyhole lock and keyhole lock key.

  • Enter your lock your door
  • Insert the keyhole lock into the keyhole
  • Insert the key of your keyhole lock into the keyhole lock and turn it to keep it in place.
  • Remove the keyhole lock key.
  • To undo the blocking, insert your keyhole lock key and turn it.

Keyhole locks are a must-have for people living in an apartment complex where their tenant has a duplicate of their tenant’s key. Moreover, what’s good about stuffing your keyhole with the keyhole lock is that it will prevent deadbolt from turning DIY.

#5 Jam a lock


Jamming a lock with an improvised keyhole-stuffing tool is another cheap yet effective method for locking someone out with a key.

This method mirrors the keyhole lock device, but the only difference is this has a permanent effect on your lock. This method requires you to ruin a lock so the existing key would be perpetually useless.

If someone has access to one of your doors, you stuff the keyhole using superglue or some toothpicks to keep a deadbolt from unlocking and simply discard it once you get a new one.

However, this method only applies to people who own the house or, if not, have an authorized person approve the action.

Remember that you must have another door when entering and leaving the house because you cannot unlock it once you jam a lock permanently.



How do you block keyholes?

Another way to block the keyhole is by mounting a metal cover over or around it. Using a keyhole lock blocker, you can secure your keyhole even when you are outside because, aside from the metal cover caging it, it is equipped with another lock to access the keyhole.

How do you lock someone’s door from the outside?

An additional external lock, specifically a padlock latch, can help you lock a door from the outside.

However, if you want to lock door from outside without key, you can use a keypad door lock which maneuvers the lock mechanism by tapping the correct number combination.


As you can see, there are plenty of ways on how to lock someone out who has a key and upgrade your security when faced with a compromising situation. You can combine different methods to secure yourself and your family further if you have the means.

If you are in grave danger, calling an authorized person can help you more than these locks, so constantly evaluate the situation and act upon it if needed.

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