High Security Locks: Anti-Snap and BS3621 Insurance-Grade Leicester

High Security Locks: Anti-Snap and BS3621 Insurance-Grade

This page is for anyone who wants their doors to actually resist a break-in attempt, and to meet the lock standards their home insurer expects. That could be after a scare on your street, ahead of an insurance renewal, or simply because the cylinder your uPVC door came with is the exact type burglars target.

Most forced entries on modern British homes are not dramatic. A euro cylinder that sticks out past the handle can be gripped and snapped in well under a minute, and the door opens. The fix is not more locks, it is the right lock, fitted properly.

The standards that matter

There is a lot of marketing noise around "high security". Only a few marks mean anything.

Anti-snap cylinders (TS007 and SS312). TS007 is the kitemark scheme for door hardware. A 3-star rating, reached by a 3-star cylinder alone or a 1-star cylinder with 2-star handles, is the level that defeats snapping. Sold Secure SS312 Diamond is a separate, harder attack test that the best cylinders also pass. We fit cylinders carrying these ratings, not lookalikes.

BS3621 mortice locks. On timber doors, insurers typically require a 5-lever mortice deadlock to BS3621, with the British Standard kitemark stamped on the faceplate. This is the mark an assessor looks for after a claim, so a lock that "looks similar" is not good enough.

Restricted keyways. For properties where keys move around (rentals, offices, holiday lets), a restricted keyway stops keys being copied without authorisation. Blanks are controlled and cut only against a registered card.

How we fit a high-security lock

The security of a good cylinder is easy to throw away with a sloppy fit, so the method matters.

1. Measure first. A euro cylinder must be sized to the door so it sits flush. A cylinder that protrudes even a few millimetres past the handle gives a burglar something to grip, which undoes the anti-snap design. We measure the door and cut nothing to guesswork. 2. Match the hardware. Where the rating relies on handles as well as the cylinder (the 1-star-plus-2-star route), we fit security handles that carry the rating too. A 3-star cylinder behind flimsy handles is not a 3-star door. 3. Fit and align. For mortice work we chisel the mortice and keep cleanly so the deadbolt throws fully into a solid keep. A BS3621 deadlock that only half-throws is not doing its job. 4. Test under load. We check the lock engages and releases smoothly, that the door pulls up tight, and that the whole assembly resists the pressure a real attempt would apply.

For the detail behind this, see our guide on installing a high-security door lock and, because handles carry half the rating on some doors, upgrading door handles for better security.

What it costs

High-security lock work is priced as a lock change. These are our real figures, inc VAT.

Based on 222 recent recorded lock change jobs. Where we hold local data:

A single anti-snap cylinder upgrade sits at the lower end. A full set of doors, or a mortice deadlock added where there was none, sits higher. Master suites and restricted keyways are quoted individually. See the pricing page for how we work it out.

When an upgrade is worth it, and when it is not

We do not think everyone needs a security overhaul. If your uPVC door still carries the standard cylinder it was built with, upgrading that one cylinder is the highest-value job in locksmithing and we will always recommend it. If you already run anti-snap cylinders and a BS3621 mortice where the door needs one, you are well protected and we will say so. Our guide are high-security locks worth it lays out the trade-off honestly. If a lock has already been attacked, that crosses into burglary repair or a straightforward lock replacement.

Every engineer we send is DBS checked and carries public liability insurance, which matters when you are handing someone the security of your home or business.

Where we fit high-security locks

We upgrade locks across Coventry, Derby, Colchester, Ipswich, Burton upon Trent, Nottingham and Leamington Spa, and the surrounding towns. Weaker uPVC cylinders are also a common cause of uPVC door problems, so the two jobs often go together.

Call us

Call 0333 006 9691 to talk through an anti-snap or BS3621 upgrade. Tell us your door type and what you have now, and we will tell you straight what is worth doing.