What type of lock is on my composite door?

The same three-part system as uPVC — euro cylinder, gearbox and multipoint strip — in a thicker slab, frequently with split-spindle function where the outside handle never opens the door without the key.

How do I identify my multipoint lock brand?

Open the door and read the stamp on the metal faceplate along the lock edge, usually near the central gearbox — Ferco, GU, Maco and Fuhr are the common Nottingham patterns.

Which door lock type is most secure?

On uPVC and composite doors, a well-aligned multipoint mechanism driven by a TS007 3-star anti-snap cylinder. On timber doors, a BS3621 five-lever mortice plus a quality nightlatch.

What is the difference between lever-lever and split-spindle?

On lever-lever doors the outside handle opens the door when unlocked; on split-spindle doors the outside handle never opens the door without the key — a security feature, not a fault.

My key turns but the door won't lock — which part is at fault?

Test with the door open: smooth operation points to door alignment, stiffness points to the gearbox, and a freely spinning key points to the cylinder.

Can the cylinder be upgraded without replacing the whole mechanism?

Yes — the euro cylinder swaps independently in minutes, which makes the anti-snap upgrade the best-value security improvement on any euro-cylinder door.

Lock Repair

uPVC & Composite Door Lock Types: Identify Yours in 2 Minutes

Max the Locksmith · July 2026

The short answer: every uPVC and composite door lock is three parts working together — the cylinder (where the key goes), the gearbox (behind the handles), and the multipoint strip (the long metal edge with hooks and rollers). Learn to name the part and you’ve halved the diagnosis, armed yourself against the classic overcharge, and made any phone call to a locksmith twice as useful. Photos of your door edge to WhatsApp do the same job even faster. Repairs run the flat £85 + parts (+ VAT) — price guide.

Part 1: the euro cylinder — the barrel your key turns

Look at the keyhole face-on: a keyhole inside a metal oval running through the door = a euro cylinder, standard on nearly every uPVC and composite door. Three formats: double (key both sides), thumb-turn (key outside, knob inside — key-free exits, kinder for kids and older hands, the usual pick for family front doors), and half (key one side only — garage side doors and stores).

Quality is where cylinders really differ. Budget brass snaps in seconds under the attack burglars actually use; TS007 3-star / BSI Kitemark anti-snap cylinders are built to fail safe. The evidence is in are anti-snap locks worth it, the ratings decoded in 1-star vs 3-star, and sizing (which matters — a protruding cylinder is a handle for burglars) in how to measure a euro cylinder.

Faults that live here: key stiff, gritty or spinning (stiff, sticking or spinning guide), key snapped off in the lock, key turns but nothing happens.

Part 2: the gearbox — the engine behind the handles

The central case that converts handle-lifting into locking. When handles flop, stick halfway, crunch, or lift without throwing anything, this is the culprit — the failure stages, the open-door test and the swap itself are all in the gearbox guide.

Two functional variants worth knowing. Lever-lever: the outside handle opens the door whenever it’s unlocked. Split-spindle (or key-wind): the outside handle never opens the door without the key — standard on many composites, and a feature that regularly gets reported as a fault by new owners. Brands you’ll meet on Nottingham doors — Ferco, GU, Maco, Fuhr — stamp their name on the faceplate along the door edge, usually near the gearbox: that stamp is exactly what to photograph before calling.

Part 3: the multipoint strip — hooks, rollers, mushrooms and shoots

Open the door and look along its edge: a full-height metal strip with hardware at intervals. Hooks pull the door into the frame; rollers and mushroom cams compress the seals and resist prying; shootbolts fire top and bottom (standard on French doors and patio pairs). Count the locking points — “3-point” or “5-point” — and you’ve described your door like a professional. The full anatomy, including why an unlifted handle means an unlocked door, is in what is a multipoint locking mechanism.

Faults that live here: one hook grinding while the rest work, a locking point that’s stopped engaging, visible damage to hooks or rail — and the great impostor, alignment: shiny scrape marks on the cams mean the door has dropped and the strip is fighting its keeps. Strip symptoms with a healthy strip are an alignment job.

Timber doors, for the comparison

Older Nottingham houses — the Lace Market, the Victorian terraces of Sherwood and Carrington — run a different family: mortice locks buried in the door edge (5-lever, ideally BS3621 for insurance) and nightlatches on the surface (the “Yale-type” latch). Same honesty applies: most faults are one replaceable part, old locks often repair rather than replace, and the overall pick-the-right-lock question is covered in best locks for front doors.

Why naming the part protects your wallet

“The lock’s broken, you need a new mechanism” is how a modest gearbox becomes a full-strip invoice. Match symptom to part: key trouble = cylinder money. Handle trouble = gearbox money. Physically damaged hooks = strip money. Scrape marks and seasonal drama = alignment money (the cheapest of all). Anyone quoting the big part for the small symptom should be able to show you the failed part and explain why — Max does both, before work starts, on every job.

The van, and the make-safe rule

All three part families, in the common patterns and sizes, travel in the van — cylinders (anti-snap included), gearboxes in both functions, strips, keeps and handles — which is why most lock jobs across Nottingham finish in one visit. The exceptions are proprietary and obsolete systems, and the rule for those is fixed: the door gets made lockable and secure the same day, the correct part goes in when it lands (usually next morning), and nobody gets upsold a full strip because it happened to be on the shelf.

What it costs (on average)

On average: cylinders £25–£120, gearboxes £20–£180, full strips £40–£250, timber mortice/nightlatch work £30–£90 — all under the flat £85 labour + VAT. Rare and proprietary mechanisms can run £250–£500+; they’re the exception and always quoted before work starts. Price guide.

Quick answers

What lock type is on my composite door?

The same three-part system as uPVC — cylinder, gearbox, multipoint strip — in a thicker slab, more often with split-spindle function. Composite-specific behaviour is in the composite lock guide.

How do I find out my multipoint brand?

Open the door and read the stamp on the metal faceplate along the lock edge, usually near the gearbox. Photograph it and WhatsApp it over — it’s the fastest route to the right part on the first visit.

Which lock type is most secure?

On uPVC/composite: a healthy, aligned multipoint driven by a TS007 3-star cylinder. On timber: a BS3621 mortice plus a quality nightlatch. Security is the combination and the condition — a misaligned multipoint is barely locked.

What’s the difference between a lever-lever and split-spindle door?

Lever-lever: the outside handle opens an unlocked door. Split-spindle: the outside handle never opens the door without the key — a feature, not a fault, common on composites.

My key turns but the door won’t lock — which part is that?

Run the open-door test from the gearbox guide: smooth in mid-air points to alignment; stiff or incomplete in mid-air points to the gearbox. A key that spins freely points to the cylinder.

Can I upgrade the cylinder without touching the rest?

Yes — the cylinder swaps independently in minutes, which is why the anti-snap upgrade is the best-value security move on any euro-cylinder door.

Sorted? What most readers check next

Not sure what you’re looking at? Photograph the door edge and WhatsApp it: 07552 421433 — £85 + parts (+ VAT), no call-out fee.

Need a locksmith in Nottingham?

Max diagnoses the fault, fixes it on the spot where possible, and agrees the price first — £85 + parts, no call-out fee, same price across Nottingham, Derby, Mansfield & Loughborough.

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