Changing the Locks When You Move into a New Home

When a property changes hands, the conveyancing process does not include a formal audit of every key ever cut. The previous owner may have lived there for twenty years, handed spare keys to neighbours, family members, or a cleaner, and simply forgotten to collect them all before completion. If the property was rented, the situation is even less predictable — letting agents, managing agents, maintenance contractors, and multiple sets of previous tenants can all have had access. Even a brand-new build can have had site workers, inspectors, and developers passing through with master keys. None of these people are necessarily dishonest, but you do not know them, and that uncertainty is worth resolving on day one rather than leaving it to chance.

Beyond security, there is a practical insurance angle. Many home insurance policies in the UK require that external doors are fitted with locks that meet British Standard BS3621, particularly the 5-lever mortice deadlock on a timber door. If you move into a property and the existing locks are old, worn, or below the required standard, your insurer may not pay out on a burglary claim. Getting the locks properly assessed and replaced from the outset removes that risk entirely.

Traditional timber front doors in Lewisham typically have two distinct locking mechanisms: a Yale-type nightlatch (the spring-loaded lock you use with a latch key every day) and a 5-lever mortice deadlock set into the body of the door itself. Changing both is the standard recommendation, and a qualified locksmith can usually complete the work in well under an hour on a straightforward door.

The nightlatch cylinder is removed and a new one — ideally an anti-pick, anti-drill, anti-bump replacement — is fitted in its place. The 5-lever mortice deadlock, if it is already BS3621-rated and in good condition, may simply need re-keying by replacing the internal mechanism with a new set; if it is worn, non-standard, or does not meet the British Standard, the entire lock body is replaced. You walk away with a fresh set of keys, the confidence that only you hold working keys, and documentation you can share with your insurer if needed. Back doors on timber frames — including French doors opening onto the garden — usually have their own mortice lock and are worth addressing at the same time.

Many properties in Lewisham, particularly those built or refurbished from the 1990s onwards, have uPVC or composite front doors. These use a multipoint locking system operated by a single handle, with several locking points engaging along the door frame simultaneously. The key-operated part of this system is a euro cylinder — the oval-shaped barrel that you insert your key into. Replacing the euro cylinder is the core task for a lock change on a uPVC door, and it is a quicker job than most people expect, though it requires the right cylinder size and specification.

The critical word here is anti-snap. Euro cylinders have a known vulnerability: if enough force is applied, they can snap at their mid-point, allowing a burglar to manipulate the internal mechanism directly. Anti-snap cylinders are designed to sacrifice the exposed outer section cleanly, leaving the internal locking part intact and the door secure. Look for cylinders rated to TS007 3-star, which is the standard insurers and police crime-prevention initiatives in the UK recognise. If the cylinder currently in your uPVC door is a standard, unbranded one — which is common in developer-spec properties and rented homes — upgrading to a TS007 3-star anti-snap cylinder on day one is one of the most cost-effective security decisions you can make. If your door is showing signs of misalignment, a stiff handle, or a lock that does not quite engage properly, that points to a multipoint lock mechanism fault rather than just the cylinder, and a skilled locksmith can assess whether upvc door lock repair is needed alongside the cylinder swap.

It would be remiss to write a guide about home locks without covering what happens when things go wrong after move-in. If you find yourself locked out of your house — key snapped in the lock, nightlatch dropped while you popped to the garden, or you simply left without your keys — the first sensible steps are to check whether any other entry point is securely accessible to you, whether a trusted person holds a spare key, and whether a window (ground floor, with care) has been left on the latch. Do not attempt to force entry yourself: beyond the risk of personal injury and door damage, it can complicate things with your insurer.

If none of those options apply, what to do when you are locked out of your house is straightforward: call a professional locksmith. A reputable locksmith London team will ask you to verify ownership or occupancy — this is normal and responsible practice, not an inconvenience. We will then attend and open the door using non-destructive methods wherever possible, meaning the lock and door remain undamaged. If the lock needs replacing after a lockout — for instance, because a cylinder has snapped — we carry common replacement parts with us and can complete the work in a single visit. Can a locksmith get into a deadlock or a multipoint lock? Yes — a trained, experienced locksmith has the tools and knowledge to open most lock types without damage, which is exactly why you want a professional rather than a DIY approach. If you are ever in this situation in the Lewisham area, call 020 3757 5731 and we will send someone straight out — we are usually with you in around 30 minutes.

When it comes to a lock change London homeowners moving into a new property have a few clear paths, and the right one depends on your door type, the condition of the existing hardware, and your insurance requirements. For timber doors: replace the nightlatch cylinder and either replace or upgrade the 5-lever mortice deadlock to a BS3621-rated model — this is the baseline recommendation for any timber front door. For uPVC and composite doors: replace the euro cylinder with a TS007 3-star anti-snap model, and if the multipoint mechanism itself is showing signs of wear or fault, address that at the same time. For back doors, patio doors, and any secondary access points: apply the same logic — a door is only as secure as its weakest lock.

One question that comes up regularly is whether you need to fully replace a lock or simply re-key it. In UK terminology, re-keying typically means replacing the cylinder or internal mechanism so that the old keys no longer work — the lock body itself stays. Do you need to re-key a new lock? If a lock has just been installed as part of a new build or recent renovation, it may still be on a master key system used by the developer or builder, in which case yes — having the cylinder changed so that only your keys work is essential. The final cost of any lock change will depend on factors including the type of lock and door, the specific cylinder specification required, and the time of day you call — we confirm an exact, up-front quote on the phone before anyone travels out, with no surprises on the day. For a 24 hour locksmith London homeowners and tenants can rely on any time — evenings, weekends, bank holidays — call us on 020 3757 5731.