Rekey or Replace Your Locks? How to Decide

When keys go missing, a tenant moves out or you move into a new home, the first thought is usually "I need new locks." Often, you do not. Rekeying gives you the same result, old keys that no longer work, without buying new hardware.

But rekeying is not always the right answer either. Some locks are too worn, too cheap or simply the wrong type for the door. This guide explains the difference between rekeying and replacing, what each costs in practical terms, and how to decide which suits your situation.

What rekeying does

Rekeying changes the inside of a lock so that a new key operates it and the old key does not.

Most Sydney homes use pin-tumbler locks. Inside the cylinder is a row of small pins in different lengths. The key lifts those pins to exactly the right heights so the cylinder can turn. When a locksmith rekeys a lock, they take the cylinder apart, replace the pins with a new set and cut a new key to match.

The lock body, the handle and the visible finish stay exactly as they were. Only the key changes.

What replacing does

Replacing a lock means taking the old lock off the door and fitting a new one. You get new hardware, new keys and, in some cases, a different type of lock altogether.

Replacement can be like-for-like, such as swapping an old deadlock for a new one of the same size. It can also be an upgrade, such as replacing a basic knob set with an entrance set and adding a separate deadlock.

The main differences

The simplest way to think about it: rekeying changes who can open the lock, while replacing changes the lock itself.

When rekeying is the better choice

Rekeying makes sense when your locks work well and you are happy with them, but you need to control who has a key.

You have just moved in. You do not know how many keys the previous owners, tenants, agents or tradespeople made. Rekeying on moving day ensures only your household holds working keys.

Keys have been lost or stolen. If the locks are fine, rekeying is the fastest way to make the missing keys useless.

A tenant or housemate has moved out. Landlords often rekey between tenancies, especially in flats and units around Greenacre and Bankstown where turnover is high.

A staff member has left a business. Rekeying the doors they had access to is simpler than replacing them.

You want one key for several doors. If your locks share a compatible keyway, a locksmith can rekey them alike so one key opens them all.

In each of these cases, the locks themselves are not the problem. Only the keys are.

When replacing is the better choice

Replacement makes more sense when the lock itself is the problem.

The lock is broken or damaged. If a cylinder is seized, a bolt will not throw, or the lock was damaged in a break-in, rekeying will not help.

The lock is badly worn. Years of daily use wear the pins and internal parts. A worn lock may rekey, but it is likely to fail again soon. Replacing it is often better value.

The lock is low quality. Some cheap locks are easy to defeat and wear quickly. Upgrading to a better lock improves security as well as solving the key problem.

You want a different type of lock. For example, a back door with only a spring latch may benefit from a deadlock. Our article on deadlocks and deadlatches explains the difference.

The lock cannot be rekeyed. Some very cheap locks, some electronic locks and some damaged cylinders cannot be rekeyed.

You are renovating. If you are replacing doors or changing the style of your home, new hardware may suit the new look.

Cost: what you are actually paying for

Rekeying is usually cheaper because you are paying mainly for labour, new pins and new keys. The expensive part of a lock, the body and mechanism, stays on the door.

Replacement costs more because you are paying for a new lock as well as fitting. The difference depends on the quality of the new lock and how easily it fits the existing holes. If a new lock is a different size, the door may need extra work to fit it neatly.

For a typical house with several working locks, rekeying them all in one visit is almost always cheaper than replacing them all. If one or two locks are worn, a sensible mix often works best: rekey the good locks and replace the worn ones, keying everything alike.

Our guide to lock rekeying costs in Sydney explains the factors behind a rekeying price in more detail.

Security: is one safer than the other?

Rekeying does not make a lock stronger. It only changes the key. If a lock is easy to pick, force or bypass, rekeying will not change that.

Replacing a lock can improve security if you choose a better lock. A quality deadlock, fitted with a heavy strike plate screwed deep into the frame, is much harder to force than a basic latch.

So if your concern is only about lost keys or unknown key holders, rekeying is enough. If you are also worried about how strong your locks are, replacement or an upgrade may be worth it. Our security locksmith page covers the most useful upgrades.

A quick checklist

Ask yourself these questions about each lock.

1. Does it work smoothly? If yes, rekeying may be enough.
2. Is it damaged or very worn? If yes, replace it.
3. Am I happy with the type of lock? If not, replace it.
4. Is the only problem who has keys? If yes, rekey it.
5. Do I want one key for several doors? Ask about keying alike.

If you are still unsure, a locksmith can usually tell you within a few minutes of looking at the lock.

Special cases

New townhouses. In growing areas such as Condell Park and Revesby, new townhouses often have good-quality hardware, but keys pass through builders, subcontractors and agents. Rekeying after handover is usually all you need.

Older homes with mortice locks. Many older timber doors in Punchbowl and Bankstown have mortice locks. These can often be rekeyed or serviced. Replacing them with a different style may mean filling and re-cutting the door, so rekeying or repair is often the better first option.

Security screen doors. Screen door locks can sometimes be rekeyed to match the main door. If the lock is weathered and stiff, replacement may be better.

Rental properties. In NSW, tenants generally need the landlord's consent before changing or rekeying locks, with some exceptions. Check our guide to landlord and tenant lock change rules in NSW before arranging work.

Businesses. If staff turnover is regular, a key plan with restricted keys may save money over time. Our commercial locksmith page explains more.

What to expect on the day

Whether you rekey or replace, a good locksmith will:

• check each lock and tell you whether it can be rekeyed;
• explain any locks that should be replaced instead, and why;
• confirm the number of keys you need;
• give you a clear cost before starting;
• test every new key in every lock before leaving;
• confirm the old keys no longer work.

Most rekeying jobs on a typical house can be finished in a single visit. Replacement takes longer, especially if new holes need to be cut.

Mistakes to avoid

• Replacing good locks unnecessarily. It costs more and achieves the same result as rekeying.
• Rekeying worn locks. They may fail soon, meaning a second visit.
• Forgetting screen doors, garages and side gates. Include them in the same visit.
• Not asking about keying alike. It is often possible and makes life easier.
• Assuming new locks are always more secure. A new cheap lock is not better than a well-made older one.

Three real-world examples

A family moving into a Yagoona brick home. The front deadlock, back door lock and two screen door locks all work smoothly. Nobody knows how many keys the previous owners made. The sensible choice is to rekey all four locks and key them alike, so one key opens every door. No new hardware is needed.

A landlord with a Greenacre flat between tenants. The entry door deadlatch is in good order, but the previous tenant returned only one of three keys. Rekeying the entry lock is quick and costs far less than a new lock. The next tenant gets fresh keys, and the missing copies become useless.

An older Punchbowl cottage after a break-in. The back door lock was forced and the cylinder is damaged. Rekeying cannot fix a broken lock, so it needs replacing, ideally with a quality deadlock and a heavier strike plate. The front door locks still work, so they can be rekeyed to match the new back door lock.

In each case, the right answer came from looking at the condition of the locks, not from assuming that new hardware is always better.

The bottom line

Rekey when your locks are in good condition and you only need to change who has keys. Replace when a lock is broken, worn, low quality or the wrong type for the door. In many homes, the best answer is a mix of both, with everything keyed alike.

To get advice on your own locks, call us on 02 5657 6414, 7 days from 7:00am to midnight, or request a quote through our contact page. You can also read more about lock rekeying and lock replacement. Tell us how many locks you have and what has happened, and we will recommend the option that genuinely suits your doors.