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British Standard Locks Explained

BS3621 is the UK security standard most home insurers require on final exit doors. Here's what it actually means.

What BS3621 covers

A British Standard mortice lock or night latch meeting BS3621 has been tested for resistance to drilling, picking and forced attack to a defined level.

How to tell

Look for the BSI Kitemark stamped on the faceplate of the lock — the curved 'kite' logo. No mark, not BS3621.

uPVC equivalents

uPVC doors don't use BS3621 mortice locks — they use multi-point mechanisms with euro cylinders. Look for 3-star anti-snap cylinders (TS007) instead.

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Frequently asked questions

Many will refuse or reduce a claim if the policy required BS3621 and didn't have it. Always check the policy wording.

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