How to check a British Standard kitemark on your lock

Insurers often ask whether your locks meet a British Standard. You can usually check in a couple of minutes, without taking anything apart.

Mortice locks on wooden doors

Open the door and look at the metal plate on the edge of the door where the bolt comes out (the faceplate). A lock that meets the standard is stamped with the BSI Kitemark and the number BS 3621. Newer locks may show BS 8621 (which opens from the inside without a key) or BS 10621.

If you only see a brand name or “5 lever”, the lock may not meet the standard. Not every 5 lever lock is BS 3621.

Euro cylinders on uPVC and composite doors

Look at the end of the cylinder, where you put the key in, on the outside of the door. A tested cylinder is marked with the Kitemark and stars, or with “TS007”, or with a Sold Secure Diamond mark (SS312).

• 1 star: the cylinder has some protection, but needs a 2-star security handle to reach the full standard.
• 3 stars: the cylinder meets the standard on its own, including resistance to snapping.
• Sold Secure Diamond: a separate test that also covers snapping, drilling and picking.

Nightlatches

Look on the case of the lock on the inside of the door. A nightlatch that meets the standard is marked BS 3621 and has a deadlocking feature, so the latch cannot be pushed back once it is locked.

If you cannot find a mark

Marks can wear away or be painted over. A locksmith can tell you what you have and whether it meets what your insurer asks for.