Locks don't carry an expiry date, and the honest answer to "how often should I change them?" is: it's about events, not calendars. A well-fitted, decent-quality lock can run for decades. What ages a lock overnight is a change in who might hold a key to it — or the slow mechanical decline that ends with a snapped key and an emergency call-out. Here are the seven moments the trade takes seriously, and what acting on each should cost.
1. The day you move in
You have no idea how many copies of your new home's keys exist — previous owners, their relatives, old lodgers, tradespeople, the letting agent's drawer. Changing the cylinders on day one converts all of those unknowns into scrap metal for a modest cost, and on most modern doors it's a quick job. Of every entry on this list, this is the one people skip most and regret hardest.
2. Keys lost or stolen
A useful rule from the trade: misplaced keys usually surface within a day; beyond that, treat them as gone. If they were lost alongside anything carrying your address — a wallet, a parcel label, a gym bag — change the locks promptly rather than hopefully. And if they were stolen rather than lost, don't wait at all.
3. After a break-in or attempted break-in
A burgled lock may be damaged in ways that don't show, and you can't know whether keys were taken, copied or photographed during the visit. Given that burglars demonstrably return to previously successful properties, fresh locks — upgraded, not like-for-like — are part of closing the door on the repeat.
4 & 5. When key-holders change, and when relationships do
Lodgers move out, cleaners change, builders finish, relationships end — and keys don't always come back, or come back uncopied. Nobody enjoys the implication, which is why the trade frames it as policy rather than suspicion: when a key-holder leaves your life, the lock turns over with them. It costs little and removes a category of worry entirely.
6. When the lock starts telling you
A key that needs a jiggle, a cylinder that's stiff on cold mornings, a handle that fights back — these are end-of-life announcements, and ignoring them is how locks fail at the worst moment. Our guide on snapped and stuck keys explains why a snapping key is usually the lock's fault, not the key's. Replacing a declining cylinder on your schedule is far cheaper than extraction and entry on its.
7. When the lock is the weak point
Sometimes nothing has happened at all — you've simply still got the builder-grade cylinder your door came with, which snaps in under a minute, or a timber door without the BS3621 deadlock your insurance wording quietly assumes. Upgrading before an event is the cheapest version of every other reason on this list.
What changing locks should cost
On uPVC and composite doors, "changing the locks" usually means swapping the euro cylinder — a quick, tidy job where the part is most of the price, from basic cylinders up to insurance-rated anti-snap. Timber-door mortice work costs more in labour. Our UK price guide sets out fair ranges for all of it, and every LocksmithLocal job is a fixed quote before work starts, with no call-out fee — find your local locksmith and turn whichever of the seven applies to you into a half-hour appointment.
