British Standard Locks Explained: What BS3621 Means for Your Home

If you've ever read your home insurance policy carefully, you'll almost certainly have seen a requirement for 'British Standard locks' or 'BS3621 locks' on all external doors. But what exactly does this mean, and how can you tell if your locks meet the standard?

BS3621 is a kitemark standard set by the British Standards Institution (BSI) that defines the minimum security requirements for thief-resistant locks. To earn the BS3621 certification, a lock must pass a series of rigorous tests including resistance to drilling, picking, and forced entry. It must also have at least 1,000 key combinations to prevent easy duplication.

For mortice deadlocks — the type commonly found on traditional wooden doors — BS3621 certification means the lock has five levers (as opposed to two or three in cheaper models), a hardened steel bolt, anti-drill plates, and anti-pick features. You can identify a BS3621 mortice lock by looking for the BSI kitemark stamped on the faceplate of the lock (the part visible on the edge of the door when it's open).

For euro cylinder locks — found on uPVC and composite doors — the equivalent standard is TS007 (one-star) combined with a matching handle (also one-star) to achieve the two-star Diamond Sold Secure rating required by insurance companies. However, anti-snap, anti-pick, anti-bump cylinders from quality manufacturers like Avocet ABS and Ultion exceed these standards.

Why does your insurance care? Because statistics clearly show that homes with BS3621 locks are significantly less likely to be burgled, and if they are targeted, the burglar is much less likely to gain entry. If your locks don't meet the standard and you're burgled, your insurance company may refuse to pay out your claim — leaving you to cover the cost of stolen items and damage yourself.

If you're unsure whether your locks meet British Standards, a locksmith can check them for you. At Oldham Locksmiths, we carry a full range of BS3621-certified locks and can upgrade your security quickly and affordably. Call 07949 139 475 for advice or a free quote.