Lock snapping is the reason a front door can look solid and still be the weakest part of a house. It works on euro cylinders — the lock in almost every uPVC and composite door — and it does not take much skill. The cylinder is gripped, snapped at its weak point, and the mechanism behind it is turned by hand.

An anti-snap cylinder is designed to break in a controlled way instead, so the part that actually operates the lock stays protected.

That much you will find on any locksmith’s website. The part nobody explains is that “anti-snap” is used to mean two quite different things, and the difference matters when you are deciding what to buy.

“Snap resistant” and “snap tested” are not the same thing

Snap resistant describes how the cylinder is built. A good one has sacrificial sections designed to shear off under force, leaving the working part of the lock intact. That is genuine engineering, not marketing, and it is what stops the common attack.

Snap tested means something narrower. It means an independent laboratory has attacked the cylinder with a defined set of tools and certified that it held up. That is a separate process, and it costs the manufacturer money, so plenty of well-made snap-resistant cylinders never go through it.

Both are worth having. But if your insurer, your landlord or a property specification asks for a particular rating, only the second one satisfies it on paper.

The three specifications worth knowing

If you are being asked for a tested cylinder, there are three the Master Locksmiths Association recognises.

Sold Secure SS312 Diamond. The original anti-snap standard and the hardest to pass, tested with a heavier set of tools than the others.

TS007 3-star cylinder. Tested specifically for snap resistance.

TS007 1-star cylinder with 2-star door furniture. Here the cylinder alone is not enough. The protection comes from pairing it with a security handle or escutcheon rated 2-star.

There is one trap in that list, and it catches people out regularly. A 1-star cylinder on its own is not anti-snap. It is tested against drilling, bumping and picking, and not against snapping. It carries a star on the face, which looks reassuring, and a good many doors have one fitted by an owner who believes the job is done.

What we fit, and when to ask for more

As standard we fit snap-resistant cylinders, built with the sacrificial sections described above and certified to EN 1303 for drilling, picking and pulling. For the great majority of homes that is the right lock, and it is a long way from the plain cylinder that came with the door.

Where a tested rating is specifically needed — an insurer asking for 3-star, a property at higher risk, a landlord’s specification — we order those in. Tell us when you call and we will bring the right thing rather than turning up and having to come back.

What we will not do is tell you that you need the dearest cylinder on the shelf when the one on your door is already fit for the job.

How to check your own door, in about thirty seconds

Go outside and look at the lock.

Look for markings on the face of the cylinder, near the keyway. A Kitemarked 3-star cylinder carries three stars. Sold Secure Diamond carries a diamond. If there is nothing there at all, it is very likely a plain cylinder with no snap protection whatsoever.

Then look at how far it sticks out past the handle. It should sit as close to flush as the door allows. A noticeable lip standing proud of the metalwork is something to grip, and grip is the whole attack.

Then look at the handle itself. If you do have a 1-star cylinder, the handle is doing half the work and needs to be rated for it.

The fault we find most often

It is not the cylinder. It is the length.

A euro cylinder comes in two halves and they are rarely the same size. Fitted too long, it protrudes, and a well-made cylinder cut wrong is still a vulnerable cylinder. Fitted too short, the key fouls the handle.

This is why sizing gets done on the door with the old cylinder out and measured, rather than guessed from a photograph. It is a small thing that undoes an expensive lock.

When a new cylinder is not the answer

Worth saying plainly, because it is easy to spend money in the wrong place.

An anti-snap cylinder defeats one specific attack. If your door has dropped and you are lifting the handle to lock it, the multipoint gearbox is under strain and that is the more urgent job. If the frame is soft, or keys hang within reach of the letterbox, the cylinder is not where the weakness is.

We would rather look at the door and tell you the lock is fine than sell you one you do not need.

What the job involves

Usually one visit, and usually under an hour. The old cylinder comes out, gets measured, and the new one goes in cut to the right length. If several doors need doing they can be keyed alike, so you carry one key instead of three.

Builders usually fit a plain euro cylinder on a new build, meeting the specification for the door and nothing more, so newer estates are often still on their original.

We agree a price before we set off. There is no call-out fee, and if we cannot solve the problem we came out for, there is no charge for the visit.

Call 07890 295804.

Scotia Locksmiths are trusted, local, mobile locksmiths serving the following areas:

Perthshire & Kinross: Perth, Crieff, Blairgowrie, Kinross, Pitlochry, Aberfeldy, Auchterarder, Scone, Bridge of Earn, Kenmore, Blair Atholl, Coupar Angus, Glenfarg, Abernethy