A slammed door and a deadlocked door are not the same job
This distinction is the first question you will be asked on the phone, because it changes everything. A door that has slammed shut is held closed only by the latch bolt — the small bevelled bolt that clicks into the strike plate. Nothing has been locked: only the spring in the lock is keeping the door closed.
A deadlocked door has been locked deliberately: the deadbolt is thrown, and on a multipoint lock several locking points are engaged at the top, bottom and centre of the door leaf. The mechanical resistance is in a different league altogether.
In practice, a door that has simply slammed shut can usually be opened without touching the cylinder. A deadlocked door means working on the lock itself, and the question of replacing the cylinder then genuinely arises.
The techniques a locksmith uses
A professional always starts with the least invasive method the door in front of them allows. The choice depends on the type of lock, the condition of the door frame, the available clearance, and whether a seal or trim strip is present.
- The shim (or "card") technique
A thin blade slipped between the door leaf and the frame pushes back the latch bolt. Only suitable for slammed doors, with no tight weather seal and no hook-shaped latch.
- Picking
Manipulating the cylinder pins with dedicated tools to reproduce the action of the key. Success depends heavily on the cylinder's level of protection.
- Mechanical bypass
Acting directly on the mechanism without going through the cylinder, where the configuration of the lock and the door allows it.
- Drilling the cylinder
The last resort when the other methods fail. The cylinder is destroyed and must be replaced; the door and the lock itself are preserved.
Why nobody can promise a "non-destructive" opening
Some adverts guarantee an opening that is "always damage-free". That is a promise that cannot be kept in every case, and it should be treated with caution.
A recent high-security cylinder, A2P certified, is designed precisely to resist picking, drilling and snapping. A multipoint lock engaged at three points on a reinforced door offers resistance that is its very reason for being. A key broken off inside the cylinder, a seized mechanism or a broken internal part also change the picture.
Good practice looks different: the locksmith examines the door, explains what they find, tells you which method they intend to use and what it involves — including replacing the cylinder if necessary — and then draws up a quote before starting.
What you will be asked before the door is opened
A reputable locksmith does not force a door simply because someone asks. You will be asked to show that you actually occupy the property: an identity document showing the address, a rent receipt, an energy bill, a home insurance certificate, a tax notice.
If your papers are locked inside, say so on the phone: other evidence may be accepted, such as confirmation from a neighbour, the building caretaker or the managing agent (syndic). This check protects you as much as it protects the tradesperson.
Work on a communal area, or on a home where you are neither the tenant nor the owner, requires the agreement of the landlord or the managing agent, or a court order.
What to do while you wait for the locksmith
First check every other way in: side door, French window, a ground-floor window left ajar. Ask whether a spare key is held by someone close to you, by the caretaker or by the managing agent.
Do not try to force the door yourself. A rigid card used badly snaps off in the rebate, a screwdriver damages the door frame, and a mistreated cylinder seizes up for good. The result is almost always a longer and more expensive job.
Keep yourself safe, especially at night or in bad weather: a building lobby, an open shop, a neighbour's home. Keep your phone charged and reachable so you can be called back.