Lock standards sound like alphabet soup, but they matter, because they are the difference between a lock that resists a real attack and one that just looks the part. Here is what each of the main ones means, in plain English, from a locksmith who fits them every week.
We fit these standards every week on doors across Hythe, Fawley, Marchwood and the wider New Forest, so if you're unsure what your insurer wants, ask and I'll tell you straight.
The short version:
- BS3621 is the British Standard most insurers want on exit doors
- uPVC and composite doors need TS007 three star euro cylinders
- Three stars: one star cylinder plus two star handle works too
- SS312 Diamond is a tougher cylinder grade for high-risk doors
- Look for the Kitemark symbol stamped on the lock
- Free home security check, we only suggest changes that matter
BS3621, the insurance benchmark
BS3621 is the British Standard most home insurers ask for on final exit doors. A lock that meets it has been tested to resist drilling, picking and forcing to a set level, and it carries a British Standard Kitemark, the little heart-shaped symbol, stamped on the faceplate or cylinder. If your policy mentions an approved or British Standard lock, this is almost always what it means. Our insurance approved locks guide goes deeper on the policy side.
TS007 and the star rating, for euro cylinders
uPVC and composite doors usually use a euro cylinder, and the standard there is TS007, measured in stars. The aim is three stars of total protection against snapping. You get there two ways. Either a three star cylinder on its own, or a one star cylinder paired with a two star security handle, which adds up to three. An anti-snap cylinder upgrade is the most common fix we do for this, because so many doors were fitted with cheap, unrated cylinders as standard.
SS312 Diamond, the higher cylinder grade
Sold Secure SS312 Diamond is a tougher cylinder test that goes beyond snapping to cover drilling, picking and bumping as well. On a high-risk or high-value door it is worth the small extra over a standard three star cylinder. For most homes a good three star anti-snap is plenty, but it is useful to know the next step up exists.
Sold Secure, the real-world attack test
Sold Secure is run by the Master Locksmiths Association and rates products, including key safes and locks, by how they hold up to actual attack tools, graded Bronze, Silver, Gold and Diamond. For a key safe, a Sold Secure rating is the difference between secure storage and a box that hands over your key. It is the rating police schemes look for.
The Kitemark, what the symbol means
The BSI Kitemark is independent proof that a product genuinely meets the standard it claims, not just that the maker says so. If you can see the Kitemark stamped on the lock, it has been tested and audited. No mark, no guarantee. It is the first thing to look for when you check your own doors.
What this means for your door
For a typical Waterside home, that usually means a BS3621 mortice or nightlatch on a wooden final exit door, and an anti-snap three star euro cylinder on a uPVC or composite door. The common mismatch we see is a smart-looking front door with an old, unrated cylinder, which is the security equivalent of a strong gate on a low fence. If you are not sure what you have, we will tell you on a free home security check and only suggest changes that actually move the needle. For the words behind the words, the Locksmith Glossary has every term defined.
Frequently asked questions
What is BS3621?
It is the British Standard most insurers require on final exit doors. A BS3621 lock resists drilling, picking and forcing to a tested level and carries the Kitemark symbol.
What does TS007 three star mean?
It is the standard for euro cylinders against snapping. You reach three star protection either with a three star cylinder, or a one star cylinder plus a two star security handle.
What is SS312 Diamond?
A tougher Sold Secure cylinder test covering snapping, drilling, picking and bumping. It is worth considering on high-risk or high-value doors, above a standard three star cylinder.
What is Sold Secure?
A real-world attack test run by the Master Locksmiths Association, grading products Bronze, Silver, Gold or Diamond. It is the rating police schemes and key safes are judged by.
How do I know if my lock meets the standard?
Look for the British Standard Kitemark, a heart-shaped symbol, stamped on the lock. No Kitemark means no independent proof it meets the standard.
Which standards does my home actually need?
Typically BS3621 on wooden exit doors and an anti-snap three star euro cylinder on uPVC or composite doors. We can confirm yours on a free security check.
Need a locksmith now? Bugsy answers the phone himself, no call centre. No call-out fee. Call 07453 327708 for a quick honest quote.
Bugsy Edwards
Founder, Keywise 24hr Locksmiths. Family-run on the SO45 Waterside.
This advice comes from a working locksmith, not a content writer. Bugsy answers his own phone, and was named the Hampshire Police and Crime Commissioner's 2024 Community Volunteer of the Year. 5.0 from 288 Google reviews.
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