Locks explained
Door Lock Types: Which Lock Is on Your Door?
Most UK front doors use one of three lock types: a euro cylinder working a multipoint lock on uPVC and composite doors, or a mortice deadlock and a night latch on timber doors. Smart locks sit on top of these. Knowing which you have tells you the standard to ask for and roughly what a fitted replacement costs.
What are the main door lock types in UK homes?
Four types cover nearly every house and flat door.
- Euro cylinder with a multipoint lock: the keyed barrel on uPVC, composite and many aluminium doors. Lifting the handle throws hooks or bolts along the edge; the key then locks them. - Mortice deadlock or sashlock: a lock body cut into the edge of a timber door, worked by a lever key. - Night latch: the box on the inside face of a timber door, often called a Yale-type lock, that latches when the door shuts. - Smart lock: a keypad, fingerprint or app lock, either added to an existing cylinder or replacing it.
Internal, patio, garage, shed and gate locks are their own families, and each has its own page in this section.
How can you tell which lock you have?
Look at the key and at the edge of the door. A flat key with cuts along one edge, going into a teardrop-shaped barrel under the handle, belongs to a euro cylinder. A longer key with a round stem and a flag-shaped bit is a lever key for a mortice lock. If the door's edge shows a long metal strip with several bolts or hooks, the lock is multipoint. A box screwed to the inside face of the door, with a small knob to turn, is a night latch. Many timber front doors carry a night latch and a mortice deadlock together, and both count when an insurer asks what is fitted.
Which standard should each lock meet?
The standard depends on the door, not the brand.
- Timber doors: a mortice deadlock or night latch to BS 3621, marked on the faceplate with the Kitemark. Where people must get out without a key, BS 8621 or BS 10621 versions are used. - uPVC and composite doors: a euro cylinder to TS 007 3 star, or a 1 star cylinder behind a 2 star handle, or Sold Secure SS 312 Diamond. These are the grades tested against snapping. - Whole doorsets: PAS 24 tests the door, frame and hardware together.
Home insurers usually name these standards, though the wording varies by insurer, so read your policy before buying anything.
What does a fitted lock cost?
These are the published ranges this site uses, checked in October 2026:
- Euro cylinder change: £105 to £175 fitted (MLA price list; MyJobQuote). - Anti-snap cylinder: £137 to £150 fitted (MLA price list; Checkatrade). - Mortice deadlock to BS 3621: £100 to £205 fitted (MLA price list, Checkatrade, MyJobQuote and Bark). - uPVC multipoint mechanism or gearbox: £85 to £300 (MLA price list; MyJobQuote).
Where a job falls in each range turns on the grade of lock, the length of cylinder and whether the door needs work to take the new part. Evenings and weekends add £50 to £100 (MyJobQuote).
When should you call a locksmith rather than fit a lock yourself?
A like-for-like cylinder swap is within reach of a careful householder with a working key. Call a locksmith when a timber door needs a mortice lock of a different size, when a multipoint door is stiff or the handle no longer lifts, when keys are lost and you do not know who holds copies, or after a break-in. Ask for the standard to be written on the invoice, because insurers ask for it after a claim. A locksmith based near you can usually give a range on the phone once you describe the door, the key and what is stamped on the faceplate.
Common questions
What is the most secure type of door lock?
No single type wins on every door. On timber, a BS 3621 mortice deadlock is the usual insurance benchmark. On uPVC and composite, a multipoint lock is only as strong as its cylinder, so look for TS 007 3 star or SS 312 Diamond.
Do I need two locks on a timber front door?
Many insurers expect a BS 3621 deadlock on final exit doors. A night latch on its own often does not meet that unless it is a BS 3621 deadlocking version. Check your policy wording, which varies between insurers.
What is a euro cylinder lock?
It is the keyed barrel found on most uPVC and composite doors. It works the multipoint lock inside the door and can be changed on its own without replacing the mechanism, which is why it is the commonest lock change.
Can a locksmith tell me which lock I need over the phone?
Often, yes. Describe the door material, the shape of the key and what you see on the door edge. A photo of the faceplate helps, because the standard and the size are usually stamped on it.