Rekey or Replace Locks? How to Decide What Your Door Needs

When people move into a new home, lose their keys or change tenants, the usual question is whether to rekey the locks or replace them. Both make old keys stop working. They differ in cost, in what you end up with, and in when they make sense.

This guide gives you a simple way to decide, explains the trade-offs honestly, and covers the situations where the answer is clearly one or the other.

What each option does

Rekeying keeps the lock on the door and changes the pins inside the cylinder, so old keys no longer work and new keys do. The hardware you see stays the same.

Replacing removes the old lock completely and fits a new one. You get new hardware, new keys and, if you choose well, a better level of security.

Both options solve the key problem. Only replacement changes the lock itself.

A simple way to decide

Ask yourself three questions about each lock.

1. Does the lock work well?

If the key turns smoothly, the bolt extends fully, the handle is firm and the door closes cleanly, the lock is in good condition. Rekeying is usually the better choice.

If the key grinds, the bolt sticks, the handle is loose or the lock has been patched before, it may be close to the end of its life. Replacement, or at least a repair, is worth considering.

2. Is the lock secure enough?

Some locks work perfectly but offer little real security: very cheap deadlatches, old rim locks on vulnerable doors, or a single latch on a laneway back door. Rekeying gives you new keys for a weak lock. If security is a concern, replacing or adding a lock is the better spend.

3. Do you want something different?

If you want a stronger deadlock, a different style, a restricted key that cannot be copied at a kiosk, or keyless convenience, replacement is the only way to get it.

If you answered "yes, yes, no", rekey. If you answered "no" to either of the first two, or "yes" to the third, replace.

When rekeying is clearly the right choice

You have just moved in and the locks are fine

This is the most common situation. You have no idea who has copies of the old keys, but the locks themselves are good. Rekeying solves the real problem for less.

You lost your keys

If the locks are in good shape, rekeying makes the lost keys useless.

A tenant, housemate or staff member has left

Rekeying cancels their keys without changing the hardware.

You want one key for every door

While rekeying, the locks can be set to work on one key. This is called keying alike, and it is one of the best-value things you can ask for.

Budget matters

Rekeying usually costs less, because you are not buying new locks. See our guide to lock rekeying costs.

When replacement is clearly the right choice

The lock was damaged in a break-in

A lock that has been forced may be weakened inside even if it still turns. Replace it, and check the frame and strike plate too, as they often take most of the damage.

The lock is worn out

New pins will not fix a worn bolt, a broken spring or a loose mechanism.

The lock cannot be rekeyed

Some cheap or sealed cylinders are not designed to be opened. Some restricted systems can only be rekeyed by the business that holds the key system.

The lock is poor quality on an important door

If your front door or laneway back door relies on a weak lock, replacing it with a quality deadlock is better than rekeying it.

You are upgrading security

A new deadlock, a restricted key system or a stronger strike plate needs new hardware.

The middle option: repair

Sometimes neither rekeying nor replacement is needed. A lock that sticks is often not broken at all. In older terraces, doors drop and timber moves with the seasons, so the bolt stops meeting the strike cleanly. Cleaning, the right lubricant or a small adjustment can bring a lock back to full working order.

If your problem is a sticky lock rather than unknown keys, start with our lock repair page.

Comparing the two side by side

Situations that need a bit more thought

Rental properties

In NSW, landlords and tenants generally need to agree before locks are changed, and each must receive a key. Whether you rekey or replace, check your lease and talk to your agent first. Our guide to landlord and tenant lock change rules in NSW explains this.

Apartments

You can usually rekey or replace the lock on your own lot door. Building entries, car park gates and common areas belong to the owners corporation. Some buildings also require lot door hardware to match a particular style or fire rating, so check your by-laws before replacing.

Heritage doors

Older terrace doors in Surry Hills, Paddington and Darlinghurst often have original mortice locks. If the lock works, rekeying or repairing it keeps the door intact. Replacing it may mean cutting the door, which cannot be undone.

Businesses

For a shop or office, rekeying is the usual answer after a staff change. If you are moving into new premises or keys are regularly going missing, a master key system or restricted keys may be the better long-term investment. See commercial locksmith and security locksmith.

Three real-world examples

These are typical situations we see around Surry Hills. The details are simplified, but the reasoning is exactly how we decide.

A rented terrace after the tenants change

The front door has a deadlatch and a deadlock, both from a reputable brand, both working smoothly. The back door has a deadlock in similar condition. Nobody knows how many keys the last tenants handed out.

The answer: rekey all three and key them alike. The hardware is good, so replacing it would cost more for no extra security. The landlord and new tenant each get keys, and the outgoing tenants' keys stop working.

An apartment after a break-in attempt

Someone has tried to force the lot door. The lock still turns, but the key is now stiff and the faceplate is bent.

The answer: replace the lock and check the frame. A lock that has been forced may be weakened inside even if it still works. We would also look at the strike and the door edge, because that is where force usually goes. If the building has a particular style or fire rating for lot door hardware, the replacement needs to match it.

A Paddington heritage door with an original mortice lock

The lock is decades old but solid, with a large brass faceplate set neatly into the door. The new owners want to be sure the old keys are gone.

The answer: rekey or service the original lock if parts are available. Replacing it would mean either finding hardware of exactly the same size or cutting the door, and cutting a heritage door cannot be undone. If the owners want more strength, a carefully placed additional deadlock is usually better than removing the original.

The cost of getting it wrong

Choosing badly in either direction has a cost.

• Rekeying a worn-out lock means paying for labour on hardware that may fail in a few months. You then pay again to replace it.
• Replacing good locks unnecessarily means paying for new hardware you did not need, and sometimes for new holes in the door.
• Doing nothing after moving in or losing keys leaves an unknown number of working keys in circulation. That is the most expensive mistake if something goes wrong.

A few minutes checking each lock before deciding avoids all three.

What a good locksmith will do

A good locksmith checks each lock before recommending anything. They will tell you which locks are worth rekeying, which are worth replacing, and which just need an adjustment. If someone recommends replacing every lock without looking closely, it is fair to ask why.

When we rekey, we check each lock first. If one is close to failing, we tell you and let you decide. We will not replace a lock that rekeying would handle.

Doing both at once

You do not have to pick one answer for the whole house. It is common to rekey the good locks, replace the one worn lock, and key them all to the same new key. You end up with one key, every lock in good condition, and no old keys in circulation. Mixing the two options this way is often the best value, and a good locksmith will suggest it when it fits.

A quick checklist

Before you call, it helps to know:

• How many locks you have, and on which doors.
• What each lock looks like. A photo of each lock face and key is ideal.
• Whether any lock is sticking, loose or damaged.
• Whether you want one key for every door.
• Whether you rent, own, or manage the property.

With that information, a locksmith can give you an accurate recommendation and quote on the phone.

The bottom line

Rekey if your locks work well, are secure enough and you just need control over who has keys. Replace if a lock is worn, damaged, weak, cannot be rekeyed, or you want better security. Repair if the problem is a sticking lock rather than unknown keys.

For honest advice on your own locks, call Surry Hills Locksmith Service on 02 3820 5414, open 7 days, 7:00am to 12:00am, or request a quote and we will call you back.