Composite Door LocksSouth London Specialists
We fit, repair and upgrade the multi-point gearbox, hooks, cylinders and handles that secure every composite front door from Croydon to Dulwich. Like-for-like cylinder swaps, TS007 3-star anti-snap upgrades, full mechanism replacements — quoted before we touch a screw.
Composite Doors Are Tough. Their Locks Aren't.
A composite door slab will resist a kick all day. The mechanism behind the handle — the gearbox, the hooks, and especially the cylinder — is what fails, and it's what burglars target.
Composite doors arrived on UK streets around 2008 and are now the default front door on roughly two thirds of new South London builds. The slab is glass-reinforced plastic skinned over a high-density polyurethane foam core, then bonded onto a hardwood subframe. They look like wood, weigh about 35 kg, and don't warp the way timber does. The locking system underneath, however, is a small mechanical assembly — a multi-point gearbox driven by a Euro cylinder — and it's where every composite door problem starts.
We are Locksmith South London, a DBS-checked, fully insured local team that fits, repairs and upgrades composite door locks across every CR, SE, SW, SM and BR postcode — from Croydon and Purley through to Brixton, Dulwich and Bromley. Our vans carry the common Yale, ERA, Avocet, Lockmaster, GU and Mila multi-point gearboxes, plus TS007 3-star anti-snap cylinders in every standard size, so most jobs are a one-visit fix.
This page covers everything you need before booking: how the lock actually works, what each part is called, the four ways a composite door lock fails, the security standards your insurer cares about, and the honest fitted prices for each repair. If you'd rather skip the reading, send a photo of the side of your door (where the hooks engage) on WhatsApp and we'll quote within 30 minutes — or call 020 8050 2017. Need help with a different door material? See our uPVC door locks guide or browse the full door locks hub. Looking for the broader catalogue of cylinder options? Start with the Euro cylinder lock page, then read the anti-snap cylinder upgrade guide. Already locked out? Head to composite door lock replacement for the emergency response.
For a wider read on home security and the British Standards your insurer relies on, our Locksmith Advice blog has long-form guides covering BS3621, anti-snap protection and what to do after a break-in. Need us today? Contact us or check the areas we cover.
Locksmith South London · DBS-Checked · Fully Insured · Workmanship Guaranteed
Anatomy of a Composite Door Lock
When something fails, it's almost never “the lock.” It's one of these eight components. Knowing which one helps us diagnose by phone before the van rolls.
Euro Cylinder
The brass barrel your key goes into. Sized in 5mm steps; both halves measured from the centre fixing screw outward. Lock-snapping target.
Gearbox
The rectangular case in the middle of the door edge. Translates handle lift into bolt and hook movement. The most common failure point.
Hooks
Curved bolts (typically two) that swing out and grip the keep plates. Provide pull-resistance the deadbolt alone can't.
Deadbolt
Square central bolt thrown by the cylinder cam. Locks the door against forced entry once the key turns.
Roller Cams
Round adjustable rollers between the hooks. Pull the door tight against weather-seal compression.
Latch
The sprung tongue at door-handle height. Holds the closed door before you've thrown the deadbolt.
Spindle & Handles
Square bar linking inside and outside handles through the gearbox. Snaps under repeated forced lifting.
Keep Plates
The metal strike pieces fixed into the frame that catch every hook, bolt and roller. Misalignment here causes most lift-but-won't-lock faults.
How a Composite Door Lock Actually Works
Most homeowners think the cylinder is the lock. It isn't. The cylinder is the controller; the gearbox is the engine; the hooks, deadbolt and rollers are the workforce. Understanding the chain helps you describe a fault accurately and saves you a wasted call-out.
Every composite door in South London follows the same pattern: lift the handle, the gearbox throws the bolts, turn the key, and the cylinder locks the gearbox in place. If any link in that chain wears, slips or misaligns, the door stops locking properly. The good news — you almost never replace the whole assembly. We replace the part that's failed.
Want the upgrade route? Read our guide on anti-snap cylinder locks or the multi-point locking page (the same gearboxes are used on uPVC).
Door Closes — Latch Catches
The sprung latch at handle height drops into its keep plate. Door is held shut but not locked — this is what your kids do all day.
Handle Lifts — Gearbox Engages
Lifting the handle 45 degrees rotates the spindle, which spins the gearbox cam, which drives the linkage rods up and down inside the door edge.
Hooks & Rollers Throw Out
The linkage pushes the upper and lower hooks out into their keeps and tightens the rollers against the weather seal. The door is now physically interlocked with the frame.
Key Turns — Cylinder Cam Drops Deadbolt
One key turn rotates the cam inside the cylinder, which drives the central deadbolt out and locks the gearbox so the handle can no longer drop.
Reverse to Open
Key turn back → cam retracts deadbolt → handle drops → gearbox pulls hooks and rollers back → latch releases. Five movements from one key turn and one handle drop.
Composite Door Lock Types Compared
Four mechanisms can drive a composite door. Each suits a different use case — the wrong choice means an annoyed homeowner and an insurer who won't pay out.
Multi-Point with Euro Cylinder
Fits 95% of South London composite doors
The default modern composite door setup. A 3, 5 or 7-point gearbox runs the length of the door edge, driven by a Euro cylinder. Hooks plus deadbolts plus rollers, locked together with a single key turn.
- Highest pull-out and force resistance
- Cylinder upgrades to TS007 3-star without changing the gearbox
- Insurance-friendly when fitted to PAS 24
Slam Lock
Used on HMOs & rentals
The hooks engage automatically when the door is pulled shut — no handle lift required. Common on landlord properties where tenants forget to lock up. You always need a key to re-enter from outside.
- Door is locked the moment it shuts
- Reduces tenant lockout call-outs
- Easy to lock yourself out — carry a spare key
Smart Composite Lock
Keypad, fingerprint or Bluetooth
Yale Conexis, Ultion Nuki and Mila ProLinea retrofit onto a composite door's existing multi-point gearbox. You keep the mechanical security and add app or PIN control.
- No more lost keys for kids or cleaners
- Auto-lock on close (when enabled)
- Battery-dependent — physical key still required
Night Latch as Backup
Optional secondary lock
An auto-locking night latch mounted above the multi-point gives you a backup if the main gearbox fails. Older homes sometimes use one as a slam-shut without converting the whole door.
- Independent of the main mechanism
- Can be deadlocking for higher security
- Drilling a composite slab voids most warranties
Composite Door Security Standards Decoded
Insurers don't ask “is your lock good?” They ask which kitemark it carries. Get these four right and your front door is insurance-grade. Get them wrong and a claim can be refused.
3-Star Cylinder
Cylinder Attack Resistance
The British kitemark that covers cylinder snapping, picking, drilling and bumping. 3-star resists all four for the full attack window. Ask for it by name.
Sold Secure Diamond
Independent Lab Tested
The other recognised cylinder rating. Sold Secure goes Bronze, Silver, Gold, Diamond. Diamond is the equivalent of TS007 3-star — both are accepted by every UK insurer.
Door Set Standard
Whole-Door Security
Tests the complete doorset — slab, frame, hinges, lock and glazing — against forced entry. Most new South London builds since 2015 ship with PAS 24 composite doors as standard.
British Standard Lock
Insurance Baseline
The 5-lever standard you know from timber doors. Composite doors meet the equivalent intent through a TS007 3-star cylinder paired with a multi-point gearbox — same insurer recognition.
Free door security audit on every visit. We inspect your cylinder rating, gearbox brand, hook engagement, hinge bolts and frame condition, then write you a one-page report so you know exactly where you stand against insurance criteria.
Book Free AuditSix Composite Door Lock Faults We See Every Week
Match your symptoms to the card. The right diagnosis means the right part on the van — and a one-visit fix.
Won't Lift · Handle Stiff
Worn Multi-Point Gearbox
The internal cam stripped. You can feel resistance halfway through the lift, then a grinding noise. Continuing to force it snaps the spindle.
Cylinder Loose · Snap Risk
Non-Anti-Snap Cylinder Fitted
Original developer-fit cylinders are usually 1-star at best. The exposed barrel can be snapped off in under 30 seconds with mole grips.
Door Drops on Hinges
Misaligned Hooks & Keep Plates
Composite doors creep down their hinge stack over time. Hooks that used to glide into the keeps now scrape, then fail to engage.
Key Snapped Off
Broken Key Inside Cylinder
Worn or low-cut keys snap inside the cylinder — especially on cold mornings. Pulling at it pushes the broken half deeper.
Handle Spins Freely
Snapped Spindle or Cam
The square spindle linking the handles has sheared inside the gearbox. Handle moves but bolts don't engage.
Locked Out · No Damage
Cylinder Cam Slipping
Key turns but the cam inside the cylinder no longer rotates the gearbox. Door stays locked from outside.
The Four Jobs We Do Most on Composite Doors
Cylinder Change
Like-for-like Euro cylinder swap. Sized to your existing setup, two new keys cut on site, gone in 25 minutes.
From £135Anti-Snap Upgrade
TS007 3-star or Sold Secure Diamond cylinder fitted. Cuts the burglar-snap risk to near-zero. Insurance-grade.
From £200Multi-Point Repair
Gearbox replacement, hook re-alignment, spindle and cam swap. Yale, ERA, Avocet, Lockmaster, GU and Mila on the van.
From £350Emergency Lockout
Key snapped, cylinder failed, lost keys. Non-destructive entry first wherever possible. 30-minute average.
From £120Three Steps. Same Day. Fixed Price.
No quote sheets, no “we'll call you back,” no parts ordered next week. Diagnose, quote, fix.
Call or WhatsApp
Tell us the door brand, the symptom, and your postcode. Photo of the door edge helps if you have one. We diagnose by phone in under 90 seconds.
Local Locksmith Arrives
30-minute average across South London. Van carries Yale, ERA, Avocet, Lockmaster, GU and Mila gearboxes plus TS007 3-star cylinders in every common size.
Lock Fitted & Tested
Job done while you watch. We test the multi-point throw five times, hand you new keys, take card or cash, and email a 12-month workmanship guarantee.
Local Specialists. Composite Door Knowledge.
We've worked on every major composite door brand sold in South London since 2013 — Solidor, Composite Door Studio, Endurance, Apeer, Distinction, Door-Stop. We know which gearbox each brand ships with, which cylinder size, which keep plate quirks. That brand-level knowledge is the difference between a one-visit fix and a wasted trip.
DBS Checked
Every locksmith on the team is DBS-cleared. We work in homes, schools and care settings.
No Call-Out Fee
Quote is the price. No travel charge, no out-of-hours surcharge, no hidden VAT.
30-Min Average
Vans staged across South London CR, SE, SW, SM and BR postcodes for fast dispatch.
Fixed Prices
You hear the price before we touch a screw. No surprise add-ons after the job.
Free Security Audit
One-page written report on your cylinder rating, gearbox condition and frame security.
12-Month Guarantee
Workmanship and parts covered. We come back free if anything fails inside the year.
Card or Cash
Pay how you like. Card reader on the van. Receipt emailed before we leave.
5.0 Google Rating
Hundreds of South London homeowners. Not paid testimonials — verified reviews.
TS007 3-Star Stocked
Anti-snap cylinders in 30/30, 35/35, 40/40, 45/50 and offset sizes — ready to fit today.
Six Gearbox Brands on the Van
Yale, ERA, Avocet, Lockmaster, GU and Mila — covers 95% of South London composite doors first time.
Composite Door Lock Costs — South London
Fixed fitted prices. No call-out fee. No VAT add-on. Card or cash on completion.
Cylinder Change
Like-for-like Euro cylinder. Sized to your door. Two new keys cut on site.
- Quick swap, ~25 min
- Two keys included
- 12-month guarantee
Anti-Snap Upgrade
TS007 3-star or Sold Secure Diamond cylinder fitted. Insurance-grade.
- Anti-snap, anti-pick, anti-bump, anti-drill
- Three keys included
- Insurance-friendly kitemark
Multi-Point Repair
Brand-matched gearbox replacement. Six brands stocked on the van.
- Yale · ERA · Avocet · Lockmaster · GU · Mila
- Hooks re-aligned, rollers adjusted
- 5-throw test before sign-off
Emergency Lockout
Non-destructive entry first. 30-min average. Same-day cylinder available.
- Picked open where possible
- Snapped key extraction included
- Cylinder replaced if compromised
What South London Homeowners Say
Solidor stopped locking properly — handle would lift but the hooks weren't catching. Booked first thing, on the doorstep by 10am. Diagnosed a worn Lockmaster gearbox, had the exact part on the van, fitted in 40 minutes. Quote was the price.
Insurance renewal flagged that our composite door cylinder wasn't TS007 rated. Booked an audit, they confirmed it, fitted a 3-star anti-snap the same morning. Insurer accepted the new cylinder spec on email by lunchtime.
Snapped the key in our Apeer composite door at half past nine on a Sunday night. Spoke to a real locksmith on the phone, on site within 35 minutes. Extracted the broken half, cut us new keys, no damage to the cylinder. Saved us a full lock change.
Every Composite Brand. Every South London Postcode.
Solidor, Endurance, Apeer, Distinction, Door-Stop, Composite Door Studio — on the van today.
Composite Door Lock FAQs
Pulled from real homeowner questions we get every week. If yours isn't here, ask on WhatsApp.
What type of lock does a composite door use?
How much does it cost to replace a composite door lock?
Do composite doors need anti-snap locks?
Why won't my composite door lock when I lift the handle?
Can composite doors be kicked in?
What is TS007 and why does it matter for composite doors?
Can I replace a composite door lock myself?
Other Locks We Fit on South London Front Doors
Composite door work touches every adjacent lock type. Browse the related guides for the cylinder, gearbox and security upgrades we use most.
Composite Door Locks Across South London
We work every CR, SE, SW, SM and BR postcode. Browse the network or jump to a specific area.
Explore the Site
Related Locks & Problems
Composite Door Lock Trouble?
We're 30 Minutes Away.
Talk to a real South London locksmith now. We'll diagnose the fault by phone in 90 seconds and quote you a fixed price before the van rolls.
24/7 emergency locksmith serving South London since 2015 — trusted by homeowners, landlords and businesses across Sutton, Mitcham, Wallington, Cheam, Purley and surrounding areas.