Rekey vs Replace Locks: How to Decide in Westchester

If the lock still works smoothly and your only worry is who has a key, rekey it. If the lock is broken, worn loose, corroded, damaged in a break-in or simply too weak for the door, replace it. Rekeying changes the pins inside the cylinder so every old key stops working, and you keep the hardware you already own. Replacing swaps the lock itself for a new one. For a sound lock on a sound door, rekeying is usually the one you need, and it is the gentler job on your wallet.

What rekeying actually changes

Most front door locks are pin tumbler locks. Inside the cylinder sits a row of small spring-loaded pins, each cut to a different length. The cuts on your key lift every pin to exactly the right height, the cylinder turns, and the bolt moves. Change the pins and the lock wants a different key.

That is all rekeying is. The cylinder comes out of the door, the old pins come out of the cylinder, a new set goes in, new keys are cut to match, and the cylinder goes back. The deadbolt, the handle, the strike plate and the finish on the door all stay exactly as they were.

Two things follow from that.

1. Every copy of the old key stops working at once, including the copies you forgot existed.
2. Nothing about the strength of the lock changes. A rekeyed builder-grade deadbolt is still a builder-grade deadbolt. It just has a new key.

Rekeying can also put several locks on one key. If the front door, the back door and the side door into the garage each take a different key today, they can usually be pinned to the same new key. The catch is the keyway, the shape of the slot the key slides into. Different brands often use different keyways, so a mix of brands may not all share one key without swapping a cylinder or two. Ask before you assume.

What replacing a lock changes

Replacing means a new lock body, a new cylinder, or both. It is the right answer when the problem is the hardware rather than the keys. It is also the only way to change what the lock can do: a higher grade of deadbolt, a pick-resistant cylinder with restricted keys, or a keypad or app-controlled lock.

Replacing is a bigger job on older doors. A new lock has to fit the holes already cut in the door, and when it does not, the door needs work first.

The cost logic, in plain words

There are no figures here, because the honest answer depends on your doors. The logic is still simple.

• Rekeying reuses what you own. You are paying mainly for the work and for a few new pins and keys.
• It is counted per cylinder, not per door. A door with a knob lock and a deadbolt has two cylinders. A house with a front door, a back door and a garage side door may have five or six.
• Replacing adds the price of the new hardware. That ranges widely, from a basic residential deadbolt to a high-security cylinder with a controlled key.
• Replacing can add door work. If the new lock does not match the old holes, someone has to fix that.

So for a lock that works well, rekeying is almost always the cheaper of the two. The exception is a cheap lock that is already wearing out. Paying to rekey it and then replacing it a year later is paying twice. Whoever you call, ask for the total before work starts, ask whether it is priced per cylinder, and ask how many new keys are included.

When rekeying is the right call

Rekey when the lock is sound and the keys are the problem.

• You just moved in. You have no idea how many keys the last owner handed out. Our guide to rekeying the locks in a new house covers that whole checklist.
• A key went missing. Especially if it was on a ring with anything that shows your address.
• Someone who had a key has moved on. A former roommate, a contractor, a cleaner, a dog walker.
• A tenant moved out. Most landlords rekey at every turnover.
• You want one key for every door. Keying alike is done during a rekey.

A quick test before you decide. Open the door and turn the key so the bolt throws while the door is open. If the bolt moves freely, the lock is probably fine, and any sticking you feel with the door shut is the strike plate or the door sagging, not the lock. If the bolt drags or the key fights you even with the door open, the lock itself is worn, and that points toward replacing it.

When replacing is the better answer

• The lock was forced. A bent bolt, a cracked housing or a cylinder that spins loose is finished. After a burglary, our after-a-break-in checklist walks through which locks to replace and which to rekey.
• The lock is worn out. You jiggle the key, lift the door, or try twice. New pins will not fix a worn plug.
• Salt and water got into it. Salt air works its way into cylinders over time, and a lock that has sat in flood water often comes back gritty and corroded. Cleaning sometimes works. Often it does not.
• You want a better lock. More strength, key control or a keypad means new hardware.
• You are renovating. A new finish or style is a replacement by definition.

Locks that cannot or should not be rekeyed

Most residential locks can be rekeyed. A few cannot, and a few are not worth it.

• The cheapest locks. Some are not built to be taken apart, and the parts are hard to source. A new lock often costs close to the rekey.
• Badly worn or seized cylinders. If the plug is worn or corrosion has frozen the pins, there is nothing sound left to rekey.
• Restricted high-security cylinders. These use key blanks that only an authorised dealer can supply, and rekeying may require the owner's key card or the dealer.

Smart locks sit in their own category. Changing who can get in is mostly a matter of deleting codes and app users. Most also have a physical key cylinder as a backup, and that cylinder can be rekeyed like any other.

Older Larchmont houses and the Mamaroneck waterfront

Many of the older Tudor and colonial houses in Larchmont still have their original mortise locks, the kind where the whole lock body sits inside a pocket cut into the edge of the door. The cylinder on a mortise lock is a separate piece that screws in. That matters: the cylinder can often be rekeyed or swapped on its own, so you keep the original lock body and the old hardware on the door. A tired mortise lock body is a repair or replacement question. A worn key is not.

Near the harbour in Mamaroneck, salt air is the usual reason a cylinder gives up early. Low streets in the village that flood in heavy storms add water and grit to the mix. A lock that has been through that is more often a replacement than a rekey.

Two of our technicians live in Larchmont, and Mamaroneck is next door, so both villages are home ground. For lock work in either place, see our Larchmont locksmith page or the page for locksmith service in Mamaroneck. For what a rekey involves, see our lock rekeying service.

Frequently asked questions

Is a rekeyed lock as secure as a new one?

Against old keys, yes. Every old copy stops working. Against picking, drilling or a kick, a rekeyed lock is exactly as strong as it was before, because the hardware has not changed. If strength is the worry, replace it with a better lock.

Can I rekey my own locks?

Some consumer locks, such as Kwikset's SmartKey line, are built for the owner to rekey with a small tool and a working key. A standard pin tumbler lock needs pins in the right sizes, a way to hold the springs while the plug is out, and some practice. Most people find a locksmith quicker than the learning curve.

Can a lock be rekeyed without the original key?

Usually. It takes more work, because the cylinder has to be opened or removed without the key first. Tell the locksmith on the phone that you have no working key, so they know what to expect.

Does rekeying one lock change my other locks?

No. Each cylinder is rekeyed on its own. If you want all your doors on one key, say so up front and have every cylinder done in the same visit.

Not sure which one your doors need? Call Larchmont Locksmith NY on (914) 255-6611 any hour, or send a photo of the lock through the WhatsApp chat on the site, and describe what the key is doing.