Broken Key In The Lock? Don't Touch It Yet.

A key snapped inside the lock is the situation this page mostly exists for. The blade has sheared, part of it is sitting in the keyway, and the mechanism is stuck part-way through its travel. The door is neither properly locked nor openable, which is why it gets treated as urgent even though nothing has actually broken beyond the key.

Extraction uses tools made for the purpose. A key extractor is a thin, hooked or barbed probe that runs alongside the fragment in the keyway, catches on the cuts, and draws it back out the way it went in. Done properly it takes minutes and touches nothing else. Where the break is deep, or the fragment has been pushed further in by an earlier attempt, it takes longer and occasionally requires the cylinder to be removed and worked on out of the door.

The reason improvised attempts cause so much damage is geometry. A euro cylinder’s pin chambers sit directly above the keyway, spring-loaded and finely made. Anything forced into that space — a screwdriver blade, a hacksaw blade, a bent paperclip — pushes against those pins rather than the fragment. Scoring or displacing them turns a working lock into scrap even after the key comes out.

Where the fragment is protruding slightly, people ask whether they should just pull it. Honestly, if you can grip it firmly with your fingers and it slides out with no resistance at all, that is fine. The problem is that pliers apply far more force than fingers, and the usual result is that the stub shears again flush with the face of the lock, which removes the only easy access anybody had.

• Purpose-made key extraction tools
• Euro cylinder, mortice and nightlatch locks
• Cylinder removed and worked out of the door if needed
• Deep breaks and previously disturbed fragments
• Cylinder retained wherever possible
• Attended 24 hours a day

A key that comes apart in your hand rather than in the lock is a better outcome and a clear warning. You have both halves, the lock is clear, and nothing is jammed. What you do not have is a working key, and what you have learned is that this key was at the end of its life.

Keys fail by fatigue rather than by a single event. Every turn flexes the blade slightly, and over years those micro-flexes accumulate into a crack that eventually runs. The bow — the head of the key — is the usual failure point on older keys, because that is where the most leverage is applied. Blades snap nearer the shoulder, typically where the metal is thinnest.

The important consequence is that copies matter. If this key had been copied recently, those copies were cut from a blade already carrying fatigue and worn cuts, and they will be carrying the same weakness. Cutting a fresh key from the broken one is therefore the wrong move even when it seems obvious. Where you have an original or the lock code, cutting from that gives a correct key matched to the pin heights.

This is also the moment to think about the lock rather than only the key. If every key you own for this door has become worn, the cylinder they operate has almost certainly worn with them. A new key cut correctly into a worn cylinder can actually work worse than the old key did, because the lock has adapted to the degraded profile over years. In that case replacing the cylinder and starting with a fresh set is the cleaner and often cheaper long-term answer.

• Replacement keys cut from original or code
• Assessment of remaining keys for fatigue
• Cylinder wear checked against key wear
• Fresh cylinder and key set where wear is matched
• Spare sets cut on site
• Advice on which existing keys to retire

This is the part that gets skipped, and it is the reason people call us twice. A key does not snap because of bad luck. It snaps because it has been doing mechanical work it was never designed to do, and unless that changes, the replacement key will follow it.

The most common underlying cause is a dropped door. Doors settle over years, hinges wear, and the bolt or hooks stop meeting their keeps squarely. Every lock and unlock then requires the key to force the bolt against an obstruction. You compensate without noticing — a lift of the handle, a shove of the shoulder, a particular angle — and each of those compensations is load travelling through a thin piece of brass.

The second cause is cylinder wear. Pins and springs degrade, chambers pick up grit, and the plug no longer turns freely. Stiffness is the symptom, and it develops so gradually that people describe a lock needing a firm turn as normal rather than as a fault. It is not normal. A healthy lock turns with two fingers.

The third is lubrication, specifically the wrong kind. Household oil and general-purpose penetrating spray both attract dust, and inside a pin chamber that mixture sets into a paste that binds the mechanism worse than no lubricant at all. Locks want a dry lubricant — graphite or PTFE-based. We check all three of these before leaving, because extracting a key and leaving the cause in place simply schedules the next call. Where the fix is a daylight job — a door that needs proper adjustment rather than a quick tweak in the dark — we will tell you that and book it rather than pretending an overnight visit has resolved it.

• Door alignment checked and adjusted
• Hinge drop identified and corrected
• Cylinder wear assessed honestly
• Correct dry lubricant applied
• Explanation of what actually caused it
• Recommendation only where genuinely needed

Sometimes extraction is not the end of the story. Where a cylinder was already worn to the point of failure, or where an earlier attempt has damaged the pin chambers, replacement is the honest answer rather than an upsell. We would rather show you the removed cylinder and explain what is wrong with it than simply assert that it needs changing.

When a euro cylinder is replaced, two things matter more than brand. The first is the anti-snap rating: TS007 3-star or Sold Secure Diamond, because lock snapping is the dominant forced-entry method across London and a like-for-like replacement of a plain cylinder simply restores the original weakness. The second is length. A cylinder should sit close to flush with the handle, and an over-long cylinder in a high rating is weaker than a correctly measured one in a lower grade.

On timber doors with a mortice lock the equivalent is BS3621, the five-lever standard most UK home insurance policies specify on final exit doors. The kitemark is stamped on the faceplate, and a great many London homes have five-lever locks that were never certified to it. If we are replacing your mortice lock anyway, fitting to BS3621 costs little more and keeps your insurance position intact.

It is worth doing the other external doors at the same time if any of them are due. The labour of a visit is already being paid for, and a household running one new lock and three tired ones has not really solved anything. We will tell you honestly which of your other locks have life left in them rather than quoting for the lot as a matter of course.

• TS007 3-star anti-snap cylinders
• Cylinders measured to the door, not guessed
• BS3621 five-lever mortice locks
• Removed cylinder shown and explained
• Other external doors assessed honestly
• Keyed-alike sets available

A key snapping in a shared door is a different problem because it locks out more than one person. A communal entrance, an office door, a stockroom — each affects a group, and the urgency is set by whoever needs it most rather than by whoever discovered it.

In blocks of flats the practical point is that the fragment stuck in a communal cylinder is stopping every resident, so attendance is genuinely urgent even at unsocial hours. Managing agents typically want the fragment extracted and the existing cylinder retained wherever possible, because replacing a communal cylinder means reissuing keys to every resident — a considerably larger exercise than the extraction itself.

In rentals, the question of who pays comes up immediately and is worth settling before we attend rather than on the doorstep. Broadly, a key that snapped because it was worn out is usually the landlord’s side of the line, and one that snapped because it was forced is usually the tenant’s. We do not adjudicate that, but we will invoice whichever party you agree in advance and provide a clear description of what we found, which usually settles the discussion.

On commercial doors the cause is nearly always volume. An entrance operated hundreds of times a day wears keys and cylinders on a completely different timescale, and a snapped key is often the first visible sign of a cylinder that has been degrading for months. Where a business has several doors on the same profile, it is usually worth checking all of them at that point rather than waiting for each to fail in turn. On suited or master-keyed sites this matters more, because a replacement cylinder has to be cut into the existing hierarchy correctly rather than fitted as a standalone unit, and getting that wrong quietly breaks the master key it was meant to work with.

• Communal entrance extractions
• Cylinder retained to avoid reissuing keys
• Landlord and tenant billing agreed in advance
• Written description of what was found
• High-cycle commercial cylinder assessment
• Multiple doors checked in one visit

Keys give plenty of notice. Almost every snapped key we attend had been announcing itself for weeks, and the owner had adapted to it rather than reading it as a fault. Recognising the pattern is what turns a 2am emergency into a booked repair.

The clearest sign is a key that needs a technique. If opening your door involves lifting the handle, pulling the door towards you, jiggling the key, or turning it at a particular angle, that is not a quirk of an old door. It is a description of a mechanism that no longer aligns, and every one of those movements is loading the key.

Visible bending is the second. Hold your key against a flat surface and look along it. If it is not straight, it has been flexing under load, and metal that has been bent and straightened is work-hardened at the bend and considerably more brittle there. That point is where it will shear, usually inside the lock. A bent key should be replaced rather than corrected.

The third is seasonal. Locks stiffen in cold weather as metal contracts and old lubricant thickens, so a lock that is merely firm in September becomes genuinely tight in January. If you notice your key getting harder to turn as autumn goes on, that is the moment to have it looked at. Dealing with it in October is a routine visit; dealing with it in January is an emergency callout in the dark and the rain.

The last sign is one people rarely connect: a key that has started catching slightly as you withdraw it. That usually means the pins are no longer dropping cleanly back into place, which points at grit or wear in the chambers. It is the earliest of all the warnings and by far the cheapest point at which to act.

• Keys that need a technique to work
• Visible bending along the blade
• Locks that stiffen in cold weather
• Grinding or gritty feel when turning
• Key that has started catching on withdrawal
• Booked repair rather than emergency callout