UK front doors use four main lock families, often combined: Yale-type night latches, BS3621 mortice deadlocks, euro cylinder locks, and multipoint mechanisms. Each has a role; each has security ratings; each has typical failure modes. This guide explains what each lock looks like, what it does, and when you should upgrade — covering wooden, uPVC, composite, and aluminium front doors.
1. Yale-type night latch (rim lock)
The rectangular surface-mounted lock you see on the inside of Victorian and Edwardian wooden front doors. Branded Yale most commonly. Two parts: the case on the inside, the cylinder going through the door, and a strike plate on the frame.
- What it does: Self-latches when you close the door; opens with a key from outside or a knob from inside
- Security level: Basic — alone, not enough for insurance compliance
- Cost (replacement): £35-£90 for the lock, £100-£170 fitted
- Insurance: Insufficient alone — must be paired with a BS3621 mortice deadlock
- Upgrade path: BS3621-compliant night latches (Yale 89, Union 1037) for better protection but still need pairing with a mortice
Common failure: the catch mechanism wears and the door doesn't latch reliably. Symptom: door pulls open without turning the key. Replacement is straightforward DIY.
2. BS3621 mortice deadlock
The recessed lock fitted into the edge of a wooden door. You see only the brass keyhole on the outside and the metal faceplate on the door edge. The bolt is operated by key from both sides — no thumb-turn.
- What it does: Deadlocks the door (no spring-loaded catch — won't accidentally release); requires key both sides
- Security level: High when BS3621-compliant (5+ levers, hardened bolt)
- Cost: £40-£100 for the lock, £120-£200 fitted
- Insurance: The standard residential requirement on wooden external doors
- Upgrade path: Anti-pick / anti-bump versions; pair with a BS3621 night latch for "Police 7-lever" combination
Common failure: the lever springs fatigue (15+ years), and the key turns but the bolt doesn't fully extend. Repair: usually replacement.
3. Euro cylinder (UPVC and composite doors)
The brass cylindrical bit on either side of UPVC and composite front doors, where you put the key. The cylinder is the part that actually rotates to operate the lock; the rest is the door's multipoint mechanism.
- What it does: Translates key rotation to operate the multipoint mechanism behind it
- Security level: Depends entirely on the cylinder — standard (no rating) is vulnerable; TS007 3-star is well-protected
- Cost: £20-£80 for the cylinder, £80-£180 fitted
- Insurance: Most UPVC/composite doors need TS007 3-star OR 1-star + 2-star handle
- Upgrade path: Standard → 1-star → 3-star → 3-star + Sold Secure Diamond
Common failure: lock snapping if standard non-rated cylinder. Also: salt-air corrosion in Cornwall coastal homes. See our anti-snap upgrade guide.
4. Multipoint lock mechanism
The internal mechanism inside UPVC and composite doors that fires multiple locking bolts (typically 3-5) into the frame when you lift the handle and turn the key. The cylinder is the "trigger"; the multipoint is the "muscle".
- What it does: Holds the door closed at multiple points along the frame, making forced entry much harder than a single deadbolt
- Security level: High overall — even cheap cylinders combined with a multipoint mechanism resist kicking and forced entry
- Cost: £80-£200 for the mechanism, £200-£400 fitted (full replacement)
- Insurance: The mechanism itself usually doesn't carry a BS rating — security depends on the cylinder. Some insurers explicitly require multipoint for UPVC/composite
- Common faults: Gearbox failure (the internal cog assembly that translates handle motion); see our uPVC door troubleshooting guide
5. Other lock types you might see
Sash lock
A mortice lock with both a deadbolt AND a latch (operated by handles). Common on internal doors of older properties.
Deadlock
A mortice lock with only the deadbolt (no latch). Common on outhouses and stock rooms where automatic latching isn't needed.
Cylinder rim lock (modern Yale)
An evolution of the Yale night latch — surface-mounted but with anti-jimmy bolts and BS3621 compliance options. Better than a basic Yale 88; not as good as a full mortice + night latch pairing.
Patent restricted key cylinders
Euro cylinders that use patented key blanks. Replacement keys can only be cut from a registered ownership card. Used in master key systems and high-security premises. See master key systems guide.
What you should have on a front door
Wooden front door (Victorian, Edwardian, period)
- BS3621 5-lever mortice deadlock
- BS3621-compliant night latch (top of door)
- This combination is "Police 7-lever" — fully insurance compliant
UPVC or composite front door
- Multipoint locking mechanism (factory-fitted)
- TS007 3-star + Sold Secure Diamond euro cylinder
- Anti-snap handle (some doors)
Aluminium / commercial-style door
- Hookbolt or deadbolt multipoint
- TS007 3-star cylinder
- BS8621 if commercial use
What it costs to upgrade in Cornwall
| Job | Cost |
|---|---|
| Yale night latch fitted | £100-£170 |
| BS3621 mortice lock fitted | £120-£200 |
| TS007 3-star euro cylinder fitted | £100-£180 |
| Multipoint mechanism replacement | £200-£400 |
| Full wooden front door (Yale 89 + BS3621) | £250-£400 |
| Full UPVC/composite front door (3-star + handle) | £200-£350 |
Need help identifying or upgrading the locks on your Cornwall front door? Submit your postcode — we'll connect you with a Cornwall locksmith who'll inspect, identify gaps, and quote any upgrades with itemised pricing.
Frequently asked questions
What's the difference between a Yale lock and a mortice lock?
A Yale lock (night latch) is the rectangular surface-mounted lock with a knob inside and a key cylinder outside. A mortice lock is recessed into the door edge — you only see the keyhole and faceplate. Yales auto-latch; morti deadlocks need active key turning. Most insurance-compliant wooden doors have both: mortice deadlock for security, Yale night latch for convenience.
What's a euro cylinder?
The cylindrical brass component on either side of a UPVC or composite door. It's the key-operated part of the lock, and translates rotation to the multipoint mechanism behind it. Cylinder security ratings: standard (unrated, vulnerable), TS007 1-star, 2-star (handle), or 3-star (the highest individual cylinder rating).
What's a multipoint lock?
The internal mechanism in UPVC and composite doors that fires multiple locking bolts (typically 3-5) into the frame when you lift the handle and turn the key. The cylinder is the trigger; the multipoint is the muscle. Replacement: £200-£400 fitted.
What locks should I have on my UK front door?
Wooden door: BS3621 mortice deadlock + BS3621 night latch (Police 7-lever combination). UPVC/composite: multipoint mechanism + TS007 3-star + Sold Secure Diamond euro cylinder. Aluminium/commercial: hookbolt multipoint + TS007 3-star cylinder (BS8621 if commercial).
How much does a full front-door lock upgrade cost in Cornwall?
Wooden door (Yale 89 night latch + BS3621 mortice): £250-£400. UPVC/composite (3-star cylinder + anti-snap handle): £200-£350. Both options are below £400 fitted and bring most homes to full insurance compliance.