Types of Door Locks Explained — Which One Do You Actually Have?
A plain-language guide to the lock types you'll encounter on UK residential doors — what they are, where they're used, and how secure each one is.
Half the confusion about door locks comes from not knowing what type of lock you're actually looking at. This is a reference guide — no fluff, just the information you need to identify what's on your doors and whether it's adequate.
Night-latch (Yale-type lock)
The classic slam-and-go lock. A spring-loaded latch that clicks shut automatically when the door closes. From outside, you need a key. From inside, you turn a knob or press a button. Most Yale-type locks have a "deadlocking" setting where the inside knob is disabled — useful when going to bed.
Security: Moderate. Basic Yale latches can be slid open with a credit card or similar. Deadlocking versions are more resistant. On their own, night-latches provide insufficient security for an external front door — they should always be supplemented with a deadlock.
Where you see them: Older front doors, flat entrance doors, rental properties built before the 1990s.
Mortice deadlock
Set into (morticed) the door body. The bolt is thrown manually with a key from outside; from inside, either a key or a thumb-turn. Unlike a night-latch, the bolt can't be pushed back — it's locked in position.
Security: Good (3-lever), very good (5-lever), excellent (5-lever BS 3621). British Standard versions add anti-drill, anti-saw, and anti-pick hardening. The BS kitemark is what most insurers require.
Where you see them: Timber external doors, mainly pre-2000 properties. More on five-lever mortice locks.
Euro-profile cylinder
The oval barrel you see on most modern uPVC and composite doors. The cylinder contains the lock mechanism and fits into a standard Euro-profile housing in the door. Cylinders are interchangeable — you can replace one without changing the whole lock.
Security: Varies enormously. Standard euro cylinders are vulnerable to cylinder-snapping — a 20-second attack with basic tools. Anti-snap cylinders break at a safe point before the lock cam is exposed, preventing this. Always fit anti-snap on external doors.
Where you see them: uPVC doors, composite doors, some modern timber doors.
Multipoint locking mechanism
Not a lock type in itself, but the system that operates multiple lock points on a uPVC or composite door when you lift the handle. The gearbox drives hooks, rollers, and bolts into the frame at multiple points simultaneously. The mechanism is hidden inside the door edge; you see the faceplate with the bolts.
Security: Very good when working correctly. Significantly better than single-point locking. The euro cylinder is the weak point, not the mechanism.
Where you see them: Virtually all modern uPVC and composite external doors.
Rim cylinder lock
A cylinder lock where the mechanism is mounted on the surface of the door (rim-mounted) rather than morticed into it. The nightlatch is the most common example. Lockwood-style deadbolts are a heavier rim cylinder variant.
Security: Basic rim cylinders: low. Deadlocking rim lock variants: moderate. Not the first choice for high-security applications.
Where you see them: Secondary external doors, garage doors, internal doors.
Padlock and hasp
A removable lock through a hardened steel loop. Security varies enormously based on the shackle hardness, the hasp quality, and how the hasp is fixed to the door. A hardened steel security padlock on a well-fixed hasp is genuinely effective. A cheap padlock on a flimsy hasp is not.
Security: Completely dependent on the specific padlock and installation.
Where you see them: Gates, sheds, garages, external storage.
Smart lock
A lock operated by smartphone, code pad, fingerprint, or proximity card, usually with a physical key backup. The security of a smart lock depends on: the quality of the digital component, the quality of the physical lock mechanism, and the quality of the installation.
Security: Variable. A well-engineered smart lock from a reputable brand is genuinely secure. A cheap import with poor firmware is not. The door itself is as important as the lock.
Where you see them: New-builds, rental properties with key-code access, residential properties where keyless entry is a priority.
Which one do you actually need?
| Door type | Minimum adequate | Insurer-grade | |---|---|---| | Timber external door | Night-latch + 3-lever mortice | Night-latch + BS 3621 5-lever mortice | | uPVC/composite external | Multipoint + standard cylinder | Multipoint + anti-snap cylinder | | Internal doors | 2-lever mortice | Not applicable |
See home insurance lock requirements for more on what your specific policy may require.
Sign-off
Not sure what you've got? Call 020 3780 8827 — a description or photo of the keyhole and lock faceplate is usually enough to identify the type over the phone.
Frequently asked questions
What's the difference between a deadlock and a night-latch?
A night-latch is a spring-loaded latch that clicks shut automatically when the door closes — no key needed from inside, key from outside. A deadlock is manually operated with a key from both sides and throws a bolt that can't be pushed back. They serve different purposes and most external doors should have both.
What's a euro cylinder?
The oval barrel you insert the key into on most modern uPVC and composite doors, and many timber doors. Euro cylinders are widely used because they're standardised and replaceable without changing the whole lock. Anti-snap versions should be used on external doors.
Are smart locks secure?
Modern smart locks with physical key backup and good encryption are generally secure. Cheap smart locks with poor firmware or no physical backup are a risk. The physical installation also matters — a smart lock on a weak door is still a weak door.
What lock should I have on a uPVC front door?
uPVC doors use a multipoint locking mechanism (driven by lifting the handle) and a euro-profile cylinder. The cylinder should be anti-snap — standard euro cylinders can be snapped with basic tools. Check the cylinder shows anti-snap features (usually indicated on the packaging or faceplate).
Which lock type do insurers prefer?
For timber external doors: a BS 3621 five-lever mortice deadlock. For uPVC/composite: an anti-snap euro cylinder. Check your specific policy for the exact wording.
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