Rekey or Replace Locks? How to Decide

After moving house, losing keys or a tenant leaving, the first question is usually "do I need new locks?" Often the answer is no. Rekeying gives you the same control over who can open the door, usually for less. But there are times when replacing a lock is the right call. This guide sets out how to tell the difference.

The short answer

• Rekey when the lock is in good condition and you simply need old keys to stop working.
• Replace when the lock is damaged, worn out, cannot be rekeyed, or is not strong enough for the door.

Everything below explains how to work out which situation you are in.

What rekeying does

Rekeying replaces the small pins inside the cylinder so a new key works and old keys do not. The lock body, handle and finish stay on the door. It solves one problem very well: controlling who has a working key.

It does not make a weak lock stronger, fix a broken mechanism or change the style of hardware. If any of those matter, rekeying alone is not the answer. Our lock rekeying page explains the process in detail.

What replacing does

Replacing swaps the whole lock for a new one. It solves several problems at once: worn or broken internals, poor security, unwanted style and old keys. It costs more because of the hardware, but in the right situation it is the better investment. See our lock replacement page.

When rekeying is the right choice

Rekeying usually makes sense when:

• You have just moved in and the locks work smoothly but you do not know who holds keys.
• A tenant has moved out and the locks are in good order.
• Keys were lost or stolen but the lock itself is fine.
• Someone has left the household or business and you want their key to stop working.
• You want one key for several doors and the locks are compatible.
• You like your existing hardware and it suits the door.

In these cases, rekeying achieves the security goal without discarding perfectly good locks.

When replacement is the right choice

Replacement is usually the honest recommendation when:

• The lock has been forced or damaged, for example after a break-in attempt.
• The cylinder spins, wobbles or binds even after servicing.
• Parts are no longer made for an older lock.
• The lock cannot be rekeyed, which is true of some cheap or proprietary models.
• The lock is too weak for the door, such as a basic knob lock on a front door with no deadlock.
• The door needs keyless exit for fire safety and the current lock requires a key inside.
• Salt corrosion is severe, common on ocean-facing doors in Coogee, Bronte and Bondi.

The questions that settle it

If you are unsure, these five questions usually decide it:

1. Does the lock work smoothly with the current key? If yes, rekeying is likely enough.
2. Has it been forced or damaged? If yes, replace.
3. Is it strong enough for this door? If no, replace or add a deadlock.
4. Can someone get out quickly without a key? If no, consider replacement.
5. Can it be rekeyed? A locksmith can tell you quickly.

Stiff locks: often neither

A lock that is stiff or sticky often needs neither rekeying nor replacement, just servicing. Dirt, old graphite and salt build up inside cylinders, especially near the beach. Cleaning and the right dry lubricant often restore smooth operation.

A dropped door is another common cause. If the bolt hits the edge of the strike, adjusting the hinges or strike is the real fix. Our lock repair page covers this.

Fixing these problems before rekeying is sensible: there is little point rekeying a lock that is about to fail.

Cost: why rekeying is usually cheaper

Rekeying involves labour and a few pins. Replacement involves labour plus new hardware. For locks in good condition, rekeying is almost always the lower cost. Our guide to lock rekeying costs in Sydney explains how pricing works.

That said, replacing a failing lock is better value than rekeying it and paying for an emergency call-out when it fails a few months later.

Rentals and strata buildings

In rental properties, rekeying between tenants is a common, cost-effective way to manage keys. NSW tenancy law sets rules about who may change locks and when; see our article on NSW landlord and tenant lock change rules.

In strata buildings, unit entry doors may be fire-rated, and building entry doors belong to the owners corporation. Restricted key systems cannot be rekeyed or copied without authorisation. Always check what is allowed before arranging work.

A whole-house approach

When you rekey or replace, think about every way into the property: front door, back door, side gate, garage, sliding doors and windows. Rekeying only the front door leaves other doors open to old keys.

It is often worth combining jobs: rekey the locks in good condition, replace the one that is failing, and key them all alike so one key opens everything.

Common myths

"New owners always need new locks." Not if the existing locks are good; rekeying achieves the same result.

"Rekeying makes a lock more secure against force." It does not. It changes the key, not the strength.

"Expensive locks never need rekeying." Any lock with an unknown number of keys in circulation benefits from rekeying.

"A stiff lock means it is worn out." Often it just needs cleaning or the door adjusted.

Worked examples from around Coogee

Abstract rules are useful, but real situations make the choice clearer. These are typical of the calls we take, with details changed.

The new owners on a hill street

A couple buy a Federation semi. The front door has a deadlatch fitted perhaps fifteen years ago, the back door has a matching deadlock, and the side gate has a padlock. Both door locks turn smoothly. The previous owners left two keys, but a neighbour mentions that the old tenants had a cleaner and a dog walker.

Decision: rekey. The locks are sound, so there is no reason to buy new hardware. Rekeying both doors, keying them alike and replacing the padlock with a keyed-alike one gives the owners one key for everything and certainty that nobody else holds a working copy.

The unit after a break-in attempt

A tenant in a walk-up block comes home to find marks around the cylinder of the unit door and the lock now feels gritty and loose. The landlord agrees to repairs.

Decision: replace. A lock that has been attacked may be damaged inside even if it still turns. Replacing it, reinforcing the strike and checking the door is the right call. Because the building is under strata, the hardware is chosen to suit the door and the building's rules.

The beachfront flat with a stiff key

An owner near the water says the key has been getting harder to turn for months and now needs both hands. They assume the lock is finished.

Decision: service first. The cylinder is full of salt residue. After cleaning and the right dry lubricant, it turns freely. Rekeying or replacing would have been money spent on the wrong problem. If the cylinder had been corroded through, replacement with a coastal-grade finish would have been the answer.

The share house after a tenant leaves

A housemate moves out and does not return their key. The remaining tenants ask the landlord, who agrees to a change.

Decision: rekey. The locks are in good order; the only problem is an unreturned key. Rekeying the front and back doors solves it quickly, and the landlord is given a copy of the new key as the rules require.

The old knob lock on a front door

A family home has only a basic key-in-knob lock on the front door, with no deadlock. It works perfectly.

Decision: add or replace. The lock works, but it is not strong enough for a front door. Adding a quality deadlock with keyless exit from inside, and rekeying the knob lock to the same key, is often the best balance of cost and security.

The pattern is the same each time: decide based on the condition of the lock, the strength the door needs and who holds keys, not on habit.

The honest summary

Rekey when the lock is sound and you only need to control keys. Replace when the lock is damaged, weak, unsuitable or cannot be rekeyed. Service stiff locks and fix door alignment first, and consider every entry point together.

If you would like an honest assessment of your locks in Coogee or the nearby eastern suburbs, call Local Coogee Locksmith Service on 02 5023 1337, open 7 days, 7:00 AM to 12:00 AM. You can also request a quote or read about our residential locksmith work.