If you have home insurance in the UK, the small print probably says something like "all external doors must be fitted with locks conforming to BS3621" or "euro cylinders must meet TS007 3-star standard". Most people sign the policy without reading that bit. Then they get burgled and discover the insurer won't pay because their 1980s mortice lock isn't BS3621-compliant. This guide explains what the standards actually mean, how to check what you have, and what an upgrade costs.
The two standards that matter
BS3621 — the British Standard for mortice locks
BS3621 covers mortice locks (the recessed locks fitted into wooden external doors). To meet the standard, a lock must:
- Have at least 5 levers (most older locks have 2 or 3)
- Resist forced attack for a specified minimum time
- Have a hardened steel bolt that resists sawing
- Have at least 1,000 differs (key combinations)
BS3621-compliant locks have the British Standard "kitemark" stamped on the faceplate. Look at the edge of your door where the lock bolt comes out — if there's a small shield-like logo with "BS3621" near it, you're compliant. If it's blank or just shows the manufacturer's name, you're probably not.
TS007 — the UK standard for euro cylinders
TS007 covers the euro cylinders fitted to UPVC and composite doors (the cylinder is the cylindrical bit you slide the key into). It has three star ratings:
- TS007 1-star: Basic anti-pick and anti-bump protection
- TS007 2-star: Pairs with a 1-star security door handle to achieve 3-star total
- TS007 3-star: Full anti-snap, anti-pick, anti-bump, anti-drill on its own
The big concern with euro cylinders is lock snapping — a burglary method where a thug snaps the protruding cylinder with mole grips or a hammer to access the lock mechanism. A 3-star cylinder is engineered to break in a way that doesn't compromise the lock. A standard cylinder breaks and grants entry in under 30 seconds.
The combination most policies require
- Wooden external doors: BS3621 5-lever mortice locks
- UPVC/composite external doors: BS3621 multipoint mechanism OR TS007 3-star cylinder (some policies accept 1-star cylinder + 2-star security handle as equivalent)
- Patio/French doors: locks meeting PAS 24 or with secondary locking devices
What your policy actually says
Find your home insurance policy schedule (the document you got when you bought the policy). Look for sections titled "Security requirements", "Locks specification", or "Conditions". You're looking for phrasing like:
- "All external doors must be fitted with locks conforming to BS3621 or BS10621"
- "UPVC doors must have euro cylinders conforming to TS007 3-star or equivalent"
- "In addition to the main lock, all external doors must have key-operated security bolts at top and bottom"
Read carefully — there's often a clause that says "claims may be refused if security requirements are not met". This isn't theoretical: insurance companies do investigate after burglaries, and they do refuse claims where the locks weren't compliant.
How to check what you've got
For mortice locks (wooden doors):
- Open the door
- Look at the edge of the door where the bolt comes out
- You should see a metal "faceplate" — the rectangular piece around the bolt
- BS3621-compliant locks have a small kitemark logo + "BS3621" stamped on this plate
- If it just says the manufacturer's name (e.g., "Yale", "Union") with no BS reference, it's probably pre-BS3621 (i.e., non-compliant)
For euro cylinders (UPVC/composite doors):
- Look at the side of the cylinder (the brass/silver cylindrical bit on either side of the door, around the keyhole)
- You should see a logo with stars: one star, two stars, or three stars
- If you see TS007 stamped on it with stars, you're compliant for that star rating
- If there's nothing — just smooth metal — it's an unrated cylinder and probably not compliant with stricter policies
What an upgrade costs in Cornwall
| Job | Cost | Notes |
|---|---|---|
| BS3621 mortice lock fitted | £120 – £200 | Per lock, parts + labour |
| TS007 3-star cylinder fitted | £100 – £180 | Per cylinder, anti-snap |
| Multipoint mechanism replacement | £180 – £350 | UPVC/composite full mechanism |
| Full house insurance upgrade (3-bed) | £300 – £600 | All external doors |
| Security bolts (top + bottom) | £40 – £80 per door | Required by some policies |
For most Cornwall homes, the full insurance-compliance upgrade costs £300-£600 — a fraction of an average burglary insurance claim (£3,500+). Worth doing if your locks are pre-2010 or you've never checked.
What if I don't comply?
Two scenarios:
- Nothing happens. You never get burgled, the locks don't matter, life goes on. This is the most likely outcome.
- You get burgled and the insurer investigates. They send an assessor who inspects the locks. If non-compliant, they may refuse the claim, reduce the payout, or void the policy entirely. Some insurers also charge "non-disclosure" penalties.
For renters: your landlord is responsible for the locks meeting the building insurance requirements, but you're responsible for the locks meeting your contents insurance requirements. Worth checking.
Common myths
"My door has been here for 30 years, it's fine."
If your 30-year-old lock isn't BS3621, it's not "fine" — it's pre-standard. The standard was introduced precisely because older locks were too easy to defeat.
"My insurer won't actually check."
For small claims (under £1,000), often correct. For burglary claims (£3,500 average), insurers regularly send loss adjusters who do check. We've seen multiple Cornwall claims refused or reduced for lock non-compliance.
"BS3621 is just for big cities."
No — it's a UK-wide standard built into nearly every standard home insurance policy. Cornwall is no different to anywhere else.
"I have a deadbolt, that's enough."
Not necessarily — many deadbolts are non-BS3621. The standard is about specific testing criteria, not just having a beefy-looking bolt.
How to upgrade properly
- Check your policy schedule for the exact specification required
- Inspect your existing locks (kitemark check)
- Get 1-2 quotes from local Cornwall locksmiths for the upgrade
- Ask the locksmith to confirm in writing what they're fitting (BS3621-compliant, brand, model)
- Keep the receipt and any documentation — useful if you ever claim
Want to upgrade your locks to insurance-compliant standards? Submit your postcode and we'll match you with a Cornwall locksmith who supplies and fits BS3621/TS007 locks — full quote before any work starts.
Frequently asked questions
What is BS3621?
BS3621 is the British Standard for mortice locks (the recessed locks in wooden external doors). It specifies minimum lever count (5+), resistance to forced attack, and hardened bolt construction. Most UK home insurance policies require BS3621-compliant locks on all wooden external doors.
What's the difference between BS3621 and TS007?
BS3621 covers mortice locks (wooden doors). TS007 covers euro cylinders (UPVC/composite doors). They're different standards for different lock types — both are commonly required by home insurance.
How do I know if my lock is BS3621-compliant?
Open the door and look at the edge where the bolt comes out. BS3621-compliant locks have the British Standard kitemark logo and "BS3621" stamped on the faceplate. If there's no kitemark, it's probably pre-standard.
What does TS007 3-star mean?
It means the euro cylinder is engineered to resist all common attack methods: snapping (the most common UK burglary method), picking, bumping, and drilling. 3-star is the highest rating; 1-star needs to be paired with a 2-star door handle for full protection.
Will my insurance pay out if my locks aren't BS3621?
Depends on the policy and the claim. Small claims may not get investigated; burglary claims usually do. Insurers can refuse claims, reduce payouts, or void the policy entirely if security requirements weren't met. Read your policy schedule carefully.