The right home lock is the one designed for the door, the required level of control and the people who must use it. UK homes contain several different lock families, and terms such as “deadbolt”, “cylinder”, “multipoint” and “smart lock” describe different parts or functions.
A euro cylinder is not the same as the multipoint mechanism it operates. A five-lever mortice lock is not automatically BS 3621. A smart keypad may control an existing mechanical lock without changing its resistance to force.
This guide explains the main types without mixing standards or assuming one product suits every entrance.
Last updated: 27th July 2026
Home Lock Types: The Short Answer
- Timber doors: commonly use mortice deadlocks, mortice sashlocks, nightlatches or a suitable combination.
- uPVC and composite doors: commonly use a multipoint strip controlled by a euro cylinder.
- Cylinders: control the key but are not always the complete lock; size, rating and surrounding furniture matter.
- Windows: use mechanisms designed for casement, sash, sliding or roof-window construction.
- Smart locks: change how access is authorised but do not automatically strengthen the door or bolt.
- Standards differ: BS 3621 for suitable lock assemblies, TS 007 and SS 312 for cylinders and hardware should not be treated as interchangeable.
Mortice Deadlocks
A mortice deadlock is fitted into a pocket cut in the door edge and operates a key-driven bolt. It does not normally contain a handle-operated latch, so it may be used with a separate nightlatch or other closing arrangement.
It is common on timber doors. Case size, backset, door thickness, frame keep and the amount of sound timber around the cut-out affect suitability.
Mortice Sashlocks
A sashlock combines a spring latch for ordinary closing with a key-operated deadbolt, usually used with lever handles. It is common where one lock case needs to provide both latching and deadlocking.
Handle centres, spindle position and existing cut-outs matter when replacing one. A poorly matched case can require unnecessary cutting and weaken the door.
Five-Lever Locks and BS 3621
Lever count describes the mechanism but does not prove the exact security standard. A suitable BS 3621-rated lock assembly carries relevant markings and has been assessed as a complete product.
Check the Kitemark and standard reference on the exact lock and compare it with policy wording. Installation and the frame remain essential.
Nightlatches and Rim Locks
A nightlatch is mounted on the internal door face and latches automatically when the door closes. It is operated outside by a rim cylinder and inside by a knob, handle or other control.
Basic models offer convenience but may not provide the same security as high-security variants or a suitable combined arrangement. Automatic latching also creates accidental lockout risk.
Rim Cylinders
A rim cylinder is the outside key cylinder commonly connected to a nightlatch by a tailpiece. Replacing it can restore key control without changing a serviceable internal case.
The case, mounting, external protection and internal escape should still be assessed. A new cylinder does not repair a failed latch or loose nightlatch body.
Euro Profile Cylinders
Euro cylinders are removable key components used in many uPVC, composite, aluminium and some timber or commercial doors. They may be key-key, key-thumbturn or single-sided and come in different two-sided lengths.
Correct sizing, projection and rating are critical. Police advice recommends a TS 007 three-star cylinder when changing this type of lock; SS 312 Diamond is another recognised approval route.
Oval and Other Replaceable Cylinders
Some lock cases use oval, threaded or specialist cylinders. They perform a similar authorisation role but are not interchangeable with a euro profile simply because the key action appears similar.
Profile, cam or tailpiece, length and lock-case compatibility must be identified before replacement.
Multipoint Locking Systems
A multipoint system uses a central gearbox and a long strip with hooks, rollers, mushrooms or bolts. Lifting the handle often engages the points, while turning the key secures the mechanism.
“Multipoint” describes the layout, not a guaranteed grade. Security and reliability depend on the cylinder, handles, keeps, alignment, gearbox and how the door is locked.
Automatic and Slam-Secure Multipoint Locks
Some systems project locking points automatically when the door closes. Others still require handle lifting or key operation. Marketing terms do not explain whether the door is fully deadlocked or how external handles behave.
Ask for the exact operating sequence and make sure every user understands it. Convenience should not create false confidence.
Window Locks
uPVC casement windows often use espagnolette mechanisms and locking handles. Timber casements may use stays and separate locks, while sash and sliding windows need purpose-designed fasteners or locks.
The handle alone does not prove the internal mechanism is secure. Hinges, keeps, frames, glazing and emergency escape also matter.
Padlocks
Padlocks vary by body, shackle, key control, weather resistance and independent rating. Closed-shackle designs can reduce exposed shackle access in suitable applications.
The hasp, staple, chain, gate or anchor must be at least as strong as the padlock and fixed into sound material. A premium padlock on a thin hasp is not a premium system.
Keyed-Alike Locks
Compatible locks can sometimes be keyed alike so one key operates several doors. This improves convenience and may encourage correct use.
It also increases the consequence of one lost key. Record every affected entrance and plan how future replacement will remain compatible.
Restricted and Master-Key Systems
Restricted keys can make unauthorised duplication harder. Master-key systems create access levels so selected keys operate multiple locks while others open only assigned doors.
Both require administration. Check authorisation, support duration, dealer availability, key registers and the impact of losing a high-level key.
Mechanical Keypads and Digital Locks
A mechanical keypad can provide code access without batteries, while electronic keypads may support multiple users, schedules and audit logs. They are useful where controlled access is more important than issuing physical keys.
Codes need ownership, change procedures and protection from observation. The lock body, door and escape function remain separate considerations.
Smart Locks
Smart locks may use apps, Bluetooth, Wi-Fi, keypads or biometrics. They can offer temporary access, notifications and remote administration.
Assess physical security, software support, account protection, batteries, privacy and fallback. UK consumer smart products are subject to baseline product-security requirements, but owners still need updates and secure configuration.
Thumbturns, Key-Key and Internal Escape
A thumbturn can support quick keyless exit. A key-key cylinder may offer different control but can delay escape or encourage a key to be left internally.
Choose for the actual household, nearby glazing, letterplates, children, vulnerable occupants and fire requirements. No internal operation is universally best.
Lock-Type Comparison
| Lock type | Common use | Main selection question |
|---|---|---|
| Mortice deadlock | Timber entrance | Does the case, standard, frame and separate latching arrangement suit? |
| Mortice sashlock | Timber door with handles | Are centres, case size, latch and deadbolt compatible? |
| Nightlatch | Timber entrance, automatic latching | What security grade, deadlocking and internal operation are provided? |
| Euro cylinder | Multipoint and compatible lock cases | Is the profile, length, rating, function and furniture correct? |
| Multipoint lock | uPVC, composite and some aluminium doors | Is the mechanism aligned, supportable and fully key-locked? |
| Smart lock | Managed or convenient access | What physical lock, support period and fallback sit underneath? |
Choose the Lock by a Decision Sequence
- Identify the door material, construction and existing cut-outs.
- Define whether you need latching, deadlocking, key control, access logs or remote management.
- Confirm insurance, lease, fire, warranty and escape requirements.
- Inspect frame, hinges, glazing, handles and alignment.
- Verify the exact product evidence and compatibility.
- Choose an internal operation every occupant can use safely.
- Fit, test and document the completed installation.
Common Lock-Type Confusions
Keep These Terms Separate
Cylinder versus lock: the cylinder reads the key; the case or multipoint system performs the locking action.
Five lever versus BS 3621: lever count alone does not prove the standard.
Multipoint versus secure: several locking points still need alignment, a protected cylinder and correct key use.
Smart versus strong: digital control does not automatically improve physical resistance.
Help Identifying and Choosing Locks in Northampton
KMI Locksmiths can identify, repair and replace common residential lock types in Northampton and surrounding areas, including mortice locks, nightlatches, euro cylinders and uPVC or composite multipoint systems.
Photograph the door edge, keyway, handles and visible markings before the visit. The best recommendation follows the complete door and function, not a product name alone.
Final Lock Selection Checklist
- Identify the door and complete existing lock arrangement.
- Separate the cylinder, lock case, handles and mechanism.
- Match standards to the correct product family.
- Measure profile and size accurately.
- Inspect frame, hinges, glazing, keeps and alignment.
- Choose safe internal operation and key control.
- Check smart-device support and fallback.
- Test and document every installed component.
Understanding the lock type prevents expensive mismatches and helps each door receive the security, access and escape function it actually needs.