What is BS3621?

B&B Locksmiths supplies, fits, and upgrades BS 3621 British Standard locks for homeowners, landlords, flats, and businesses across Oxford and Oxfordshire. If you need a more secure lock for a timber front door, back door, or external entrance, we can inspect the door, recommend a suitable lock, and install it correctly.

BS 3621 is the British Standard for thief-resistant, mechanically operated single-point lock assemblies that are locked and unlocked with a key from both sides of the door. Locks meeting the standard are tested against specified security and attack-resistance requirements.

BS 3621-approved locks are commonly fitted to external timber doors. They include suitable five-lever mortice deadlocks, mortice sashlocks, and certain high-security night latches. They may be recommended as part of a home-security upgrade or specified by some home-insurance policies, although customers should check the precise requirements of their insurer.

A compliant lock can usually be identified by the BSI Kitemark and a BS 3621 marking on the lock or faceplate. Not every five-lever lock complies with BS 3621, so the markings and certification should be checked rather than relying on its appearance alone.

A suitable BS 3621 lock can improve the security of timber front doors, back doors, side doors, rental properties, and commercial entrances where key operation from both sides is appropriate.

A lock upgrade may be advisable when:

The existing lock is old, worn, or damaged
A door has a two-lever or three-lever mortice lock
Keys have been lost or stolen
A property has changed ownership
Tenants or authorised keyholders have changed
An insurer requires a lock meeting a recognised British Standard
Improved security is required following a break-in or attempted break-in

BS 3621 is not suitable for every door or building. Doors on escape routes, communal entrances, or properties requiring keyless exit may need a lock meeting a different standard. We can assess the door and advise on an appropriate locking solution.

uPVC and composite doors generally use multipoint locking systems and euro cylinders rather than traditional BS 3621 mortice locks. Depending on the door and security requirements, a suitable anti-snap or British Standard cylinder may be more appropriate.

B&B Locksmiths can inspect your existing lock, advise whether it is marked as meeting BS 3621, and supply and fit an appropriate British Standard lock where required.

For BS 3621 lock fitting, British Standard lock upgrades, five-lever mortice locks, or insurance-related lock advice in Oxford and Oxfordshire, contact B&B Locksmiths for practical advice and a reliable local service.