What Is Lock Snapping and How to Prevent It

The Break-In Method Most Homeowners Have Never Heard Of

Lock snapping is one of the most common methods of forced entry through a locked door in the UK. At its peak, police data showed it was the method used in roughly one in six burglaries involving forced entry to uPVC and composite doors. Despite this, most homeowners have never heard of it and have no idea whether their own front door is vulnerable.

The method targets euro profile cylinders - the type of lock fitted to the vast majority of uPVC and composite doors in British homes. If your front door has a handle with a keyhole on each side, you almost certainly have a euro cylinder. And if that cylinder was manufactured before 2012, there is a strong chance it can be snapped in under 15 seconds.

How Lock Snapping Works

A euro cylinder has a structural weakness around its centre - specifically, at the point where the fixing screw passes through the lock body and into the cylinder. This screw hole creates a stress point. When force is applied to the exposed section of the cylinder (the part that sticks out from the door), the cylinder snaps cleanly at this weak point.

The sequence is straightforward and requires no specialist tools:

1. The intruder grips the exposed end of the cylinder - often with nothing more than a pair of pliers or a mole wrench
2. They apply sideways force, snapping the front section off
3. With the front section removed, the cam (the rotating piece that operates the locking mechanism) is exposed
4. A flat-head screwdriver or similar tool is inserted to turn the cam and retract the locking bolts
5. The door opens

The entire process can take as little as 10 seconds. No noise, no visible damage from the street, and the multi-point locking system that was supposed to make the door secure becomes irrelevant - because every one of those locking points is controlled by the single cylinder that has just been compromised.

Why This Works on So Many Doors

Two factors make lock snapping so prevalent:

Cylinder protrusion. If the euro cylinder extends more than 2-3mm beyond the face of the door handle or escutcheon plate, it gives the intruder something to grip. Many poorly fitted cylinders protrude by 10mm or more.

No snap resistance. Standard euro cylinders - the ones fitted as default by most door manufacturers and builders - were never designed to resist this type of attack. They are made from brass or zamak (a zinc alloy) with no reinforcement at the stress point. They meet basic operational requirements but offer almost no resistance to deliberate force.

The TS007 standard addressing lock snapping was only published in 2012, and widespread adoption took several years longer. Many properties still have standard cylinders installed by builders and developers with no anti-snap protection, regardless of when the door was fitted.

How to Check Whether Your Locks Are Vulnerable

You can check in under a minute without any tools:

1. Open your front door and look at the euro cylinder from the edge of the door
2. If the cylinder extends noticeably beyond the handle or door furniture on the outside, it is protruding too far
3. Look for any markings on the face of the cylinder - a genuine anti-snap cylinder will typically show a TS007 Kitemark, a Sold Secure Diamond logo, or the manufacturer’s anti-snap designation
4. If there are no security markings and the cylinder is smooth and unmarked, it is almost certainly a standard unit with no snap resistance

If your cylinder was fitted when the door was installed and you have not upgraded it since, assume it is vulnerable.

How to Protect Your Home Against Lock Snapping

1. Fit an Anti-Snap Euro Cylinder

This is the single most effective measure. Anti-snap cylinders are specifically engineered with a sacrificial snap line. If someone attempts to snap the lock, the front section breaks away at a predetermined point - but the remaining body of the cylinder stays intact inside the lock, and the cam remains protected. The locking mechanism cannot be operated.

Look for cylinders that carry one of these ratings:

• Sold Secure Diamond (SS312) - the highest level of protection for a euro cylinder. This is the standard recommended by police and insurers
• TS007 3-star Kitemark - the BSI (British Standards Institution) rating for cylinders that resist snapping, picking, bumping, and drilling
• Secured by Design - a police-backed accreditation awarded to products that meet specific crime prevention standards

Reputable brands include Ultion, Brisant-Secure, ABS, and Mul-T-Lock. A quality anti-snap cylinder costs between £25 and £80 for the part alone - a fraction of the cost of a burglary. Our uPVC locksmith service covers supply and fitting of anti-snap cylinders across London.

2. Ensure Correct Cylinder Length

Even an anti-snap cylinder offers reduced protection if it protrudes excessively from the door. The cylinder should sit flush with, or very slightly recessed behind, the door handle or escutcheon plate on the outside. This eliminates the grip point that makes snapping possible.

A locksmith will measure the door thickness and handle configuration to supply the correct length. Our guide on replacing a barrel lock in a uPVC door explains the measuring process in detail.

3. Add Complementary Security

Anti-snap cylinders address the primary vulnerability, but layered security is always stronger:

• Sash jammers - inexpensive devices fitted to the opening edge of the door that physically prevent it from being forced open, even if the lock is compromised
• Door reinforcement plates - metal plates fitted around the lock and letterbox area that make it harder to access the cylinder
• Anti-snap handles - a 2-star TS007 handle combined with a 1-star cylinder achieves 3-star protection at lower cost than a standalone 3-star cylinder
• Door chains and viewers - additional barriers that do not rely on the main lock

For a full overview of lock types and security ratings, see our guide to security door and window lock types.

Lock Snapping vs Other Break-In Methods

Lock snapping is not the only technique burglars use, but it is the easiest to execute and the hardest to detect after the fact. Other methods include:

• Lock bumping - using a specially cut “bump key” to momentarily align the pins inside a lock. Leaves almost no trace. Anti-bump cylinders resist this.
• Lock picking - manipulating individual pins with specialist tools. Slower than snapping and requires more skill. Anti-pick cylinders use security pins that resist manipulation.
• Lock drilling - destroying the cylinder by drilling through it. Noisy and obvious. Anti-drill cylinders contain hardened steel inserts that resist drill bits.

A quality anti-snap cylinder typically incorporates resistance to all of these methods - not just snapping. This is why the TS007 3-star standard tests against multiple attack types, not just one.

The Cost of Upgrading vs the Cost of a Break-In

Replacing a vulnerable euro cylinder with a high-security anti-snap alternative typically costs between £80 and £150, fitted by a professional. That figure covers the cylinder, labour, and VAT.

A residential burglary in London, by comparison, costs an average of £2,800 in stolen property and damage - before considering the emotional impact, time off work, and increased insurance premiums that follow.

If you would like to know the current cost of a cylinder upgrade, our locksmith price list has the details, or you can contact us for a free quote.

Get Your Locks Checked

City Locksmith London carries a full range of Sold Secure Diamond and TS007 3-star anti-snap cylinders and can upgrade your locks in a single visit. We cover all of London with a 25-minute response time, and our prices are fixed and transparent - the quote you receive is the price you pay. Get in touch to arrange a security check.