What does BS3621 mean?

BS3621 is the British Standard for thief-resistant locks. A lock carrying this kitemark has been independently tested and certified to resist forced entry, picking, drilling and other attack methods. Most UK home and contents insurers require BS3621 locks on external doors — fitting a non-approved lock may invalidate a claim after a burglary.

Do I need a British Standard lock on my front door?

Your insurer's policy documents will specify minimum lock requirements. Most policies for homes in England and Wales require a BS3621-certified deadlock on all external timber doors. UPVC and composite doors are typically covered by their multi-point mechanism, but the cylinder should still meet TS007 3-star. We can advise on what your door needs when we attend.

What is a five-lever mortice lock?

A five-lever mortice deadlock is the standard lock type for timber external doors in the UK. It is morticed (recessed) into the door edge and operates a deadbolt that throws into the frame. Five levers are required by BS3621 — fewer levers reduce security significantly. We supply and fit Chubb, Union and ERA five-lever locks in Ipswich.

BS3621 British Standard five-lever mortice lock on a timber front door in Ipswich

British Standard Locks Ipswich

A British Standard lock is more than a quality mark — for most UK home insurance policies, it is a requirement. If your external doors are not fitted with BS3621-certified locks, a successful burglary claim may be reduced or refused. Local Locksmith Ipswich supplies and installs British Standard locks across Ipswich and Suffolk, with same-day availability on the most common lock types.

We fit five-lever mortice deadlocks to timber doors, and advise on the correct TS007-rated cylinders for UPVC and composite doors — covering the full range of external door types found in Ipswich homes and commercial properties.

What Is BS3621?

BS3621 is the British Standard specification for thief-resistant locks. To carry the kitemark, a lock must pass independent testing for picking, drilling, forcing and manipulation. The standard is maintained by the British Standards Institution and is widely referenced in UK home and contents insurance policies as the minimum acceptable security level for external doors.

Fitting a BS3621 lock is not just an insurance requirement — it is a meaningful security upgrade. Locks that do not meet the standard are significantly easier to defeat using common tools and techniques.

If your home insurance policy requires BS3621 locks and you don't have them, a claim after a break-in can be rejected — even if the burglar caused thousands of pounds of damage.
Local Locksmith Ipswich

British Standard Lock Types We Fit

Five-lever mortice deadlock (BS3621) — the standard for timber external doors, recessed into the door edge
Five-lever mortice sashlock (BS3621) — combines a deadbolt with a latch — suitable for doors requiring a handle from outside
Rim automatic deadlatch (BS3621) — surface-mounted nightlatch meeting the standard — for timber doors in older properties
TS007 3-star cylinders — the British Standard for euro cylinders used in UPVC and composite doors
British Standard padlocks — for garages, outbuildings and secondary gates requiring a certified padlock

Five-lever BS3621 mortice deadlock being installed into a timber door in Ipswich

Insurance-approved BS3621 kitemark visible on a lock fitted in Ipswich

Same-Day British Standard Lock Installation in Ipswich

We carry Chubb, Union and ERA BS3621-certified locks on the van in standard sizes. Most installations are completed within one visit. If your existing mortice pocket needs modification to accept a new lock, we have the tools on site to do this cleanly without requiring a carpenter.

If you're upgrading a UPVC or composite door, see our anti-snap locks page for cylinder specifications. For a full security review, our high-security locks service covers all entry points. If you need a new lock fitted to replace a damaged or failed one, see our lock installation service.