LOCKSRekey or replace a lock?

What rekeying does

Rekeying changes the pins inside the lock so a new key works and the old keys don't. You keep the same lock. If you've lost a key, moved into a new place, or don't know who has copies, rekeying is usually the right fix. If you rent, ask your landlord before you rekey or change a lock.

It also lets you make several locks work with one key, which is called keyed alike. One key then opens the front door, the back door and the door to the garage. That only works when the locks take the same type of key. A Kwikset and a Schlage, for example, use different key shapes, so one of them needs a different cylinder or a new lock before they can share a key.

What replacing does

Replacing swaps the hardware. Do that when the lock is worn out or damaged, when you want a stronger lock or a different style, or when you're adding something like a smart lock. Rekeying does not make a lock stronger. A weak lock with new pins is still a weak lock.

When rekeying is the better choice

• You lost a key, or one was stolen.
• You moved in and don't know who has copies.
• Someone who has moved out or finished the job, like a former roommate, a former partner or a contractor, still has a key.
• You want every door on one key, and the locks all take the same type of key.
• The lock works fine and you like it.

When replacing is the better choice

• The lock is worn out. It's still sloppy or hard to turn with a good key and the door open, even after the mounting screws are tightened.
• It's damaged or has been forced.
• You want a stronger deadbolt or a different finish.
• You're installing a smart lock or a keypad.
• The lock can't be rekeyed. That's uncommon, but it happens with some cheap or old hardware.

What a rekey involves

On a standard pin tumbler lock from a common brand, the job goes like this:

• Take the lock off the door and remove the cylinder.
• Take off the clip or cap that holds the plug, which is the part that turns, and turn the plug a little with a key that works the lock now. Then slide it out with a tool called a plug follower, which keeps the top pins and springs from spilling everywhere.
• Swap the key pins for ones that match the new key.
• Put it back together, then check that the new key works and the old one doesn't.
• Reinstall it and test it with the door open first, then with the door closed.

You need a key that works the lock now to do this. If every key is gone, the job is harder and a rekey kit alone won't do it.

Some locks work differently. Kwikset SmartKey locks, for example, are rekeyed with the key that works now, a small tool and the new key, without taking the lock apart. If you're buying a rekey kit, match it to your lock's brand and keyway, and make sure you have a key that works the lock now.

New to how the pins work? Here's the lock explained in plain English.