Service
Anti-snap locks
An anti-snap cylinder costs from £137 fitted on the Master Locksmiths Association's 2026 list, and Checkatrade's 2026 average for an anti-snap uPVC lock change is £150. Snapping is a known attack on standard euro cylinders on uPVC and composite doors. Look for a Kitemark with three stars, or Sold Secure SS 312 Diamond.
What this covers
What it costs. Parts for an anti-snap cylinder start at £64 on the MLA's 2026 list, and fitted from £137; Checkatrade's 2026 average for an anti-snap uPVC lock change is £150. Full cost breakdown.
What the job covers
- Replacing a standard euro cylinder with a TS 007 3 star or SS 312 Diamond cylinder
- Upgrading every outside door on a house to anti-snap cylinders keyed alike
- Fitting a TS 007 2 star security handle with a 1 star cylinder
- Measuring a door so the new cylinder sits flush with the handle
- Fitting cylinders to the standard an insurer has named, shown on the invoice
What is involved
Most uPVC and composite doors, and many newer timber ones, lock with a euro cylinder: a barrel with a key on the outside and a key or thumbturn inside, held by one screw through its middle. A standard cylinder is weakest at that screw, and lock snapping is a burglary method that breaks it there. Police forces warn each autumn that burglaries rise when the clocks go back, which is when many people upgrade.
An anti-snap cylinder is built so that if the outside part is attacked, it breaks away along a sacrificial line and leaves the lock still working. Two marks show that one has been tested. TS 007 is a BSI Kitemark scheme: a 3 star cylinder resists snapping on its own, while a 1 star cylinder needs a 2 star security handle with it. SS 312 Diamond is Sold Secure's highest cylinder grade. Both are tests of the product, not checks on the person who fits it. Insurers often ask for one of the two on uPVC and composite doors, so ask for the standard on the invoice.
Fitting matters as much as the product. The cylinder should sit close to flush with the outside handle, because one standing well proud gives an attacker something to grip. A careful locksmith measures the door before ordering, fits a cylinder sized for it, and checks the multipoint mechanism still locks freely.
Many anti-snap cylinders use restricted keys that can only be copied against a key card, which is worth keeping somewhere safe. If you are changing one outside door, it is usually worth doing them all at once and having them keyed alike.
Choosing someone for the job
Ask for the total before work starts, per cylinder: the cylinder, fitting and VAT. Ask which standard it meets, TS 007 3 star or SS 312 Diamond, and for that to be written on the invoice. Ask the make, whether its keys are restricted, and how spare keys are ordered. Ask them to measure the door so the cylinder sits flush, and whether the handle needs changing too. If you have several outside doors, ask for a price to do them all keyed alike.
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Common questions
What is lock snapping?
A burglary method that breaks a standard euro cylinder at its weak point, the fixing screw, to get at the lock behind it. It affects many uPVC and composite doors. An anti-snap cylinder rated TS 007 3 star or SS 312 Diamond is made to resist it.
How do I know if my lock is anti-snap?
Look at the face of the cylinder, beside the keyhole, for a Kitemark with three stars or a Sold Secure Diamond mark. A 1 star Kitemark needs a 2 star handle to match. No marking usually means a standard cylinder. A locksmith can identify it and suggest a replacement.
What is the difference between TS 007 and SS 312 Diamond?
TS 007 is a BSI Kitemark scheme for cylinders and handles, graded by stars; SS 312 Diamond is Sold Secure's top grade for cylinders. Both test the product against snapping and other attacks. Insurers commonly accept either on uPVC and composite doors.
Do anti-snap locks affect home insurance?
Many insurers ask for a multipoint lock with a TS 007 3 star or SS 312 Diamond cylinder on uPVC and composite doors, and a BS 3621 deadlock on timber doors. Check the policy wording, and keep the invoice that shows the standard fitted in case you ever claim.