Composite door locks
Composite door won't lock or open? It's the heat, the hinges or the gearbox.
Wolverhampton, Stafford and Cannock. Honest diagnosis before anyone sells you a new mechanism.
Under the skin, a composite door locks exactly like a uPVC one: same euro cylinder, same multi-point gearbox, same handles. What is different is the slab: thicker, far heavier, and (this is the one that catches everyone out) it swells in warm weather, so a dark south-facing composite door that locks perfectly at breakfast can refuse point-blank at four in the afternoon. Nothing is broken when that happens, and it does not need the new mechanism a call centre will quote you for. Run the three checks below and you will usually know which of the four faults you have before you ring anyone. If you still need me, the all-in price is agreed on the phone before I leave the van.
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Composite door won't lock? Three checks before you call anyone
Composite doors get misdiagnosed over the phone more than any other door I work on, because the most common fault (the slab swelling in warm weather) is invisible unless you know to ask about it. These three checks take two minutes and usually name the fault before anyone charges you a penny.
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Ask yourself: did it lock fine this morning?
This is the composite-door question, and no national call centre will ask it. If the door locked first time in the cool of the morning and fights you in the afternoon, the slab has expanded in the heat and the locking points are missing their keeps. Dark doors on sunny elevations are the classic case. Nothing is broken. Wait for the evening cool and try again: if it locks smoothly once the temperature drops, you have just diagnosed thermal expansion for free, and the fix is an adjustment, not a new lock.
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Lift the door by the handle edge and try locking again
Grip the lever and gently lift the whole door upwards as you raise the handle. A heavy composite slab drops on its hinges sooner than a uPVC one, and if the door locks while you are taking its weight, the hooks are missing their keeps by a few millimetres. That is a hinge and keep adjustment on the doorstep, usually with no new parts. If lifting changes nothing, the fault is inside the door edge, which is the next check.
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Take the key out and feel what the handle is doing
With the door open and the key out, lift the handle and watch the hooks throw from the door edge. If the handle will not lift with the door open, or feels crunchy and loose, the multi-point gearbox is failing and the door itself was never the problem. If the handle is fine open but stiff closed, you are back to alignment or heat. And if the handle lifts but the key will not turn, the euro cylinder has seized. Thirty seconds, and it tells me on the phone exactly which part to bring.
Heat, hinges, gearbox or cylinder: which one is it?
Match your symptom to one of the four branches below. Two of the four are adjustment jobs with no new parts, and those are exactly the two that get quoted as "you need a new locking mechanism" by people who never asked whether the door locks in the morning.
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If the door locks fine in the morning but won't lock on warm afternoons...
Thermal expansion. The slab has absorbed heat and grown, so the hooks and rollers no longer line up with the keeps in the frame. Dark-coloured composite doors on south-facing elevations are the worst affected, and the swelling reverses as the door cools. Do not force the handle and do not let anyone sell you a new mechanism for this: the honest fix is easing the keeps and adjusting the hinges so the door has clearance on hot days, from £90 with no new parts. The full hot-weather section below covers it.
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If the handle needs slamming, lifting or shoulder pressure to lock at ANY temperature...
The door has dropped on its hinges. A composite slab is heavy (roughly double a uPVC panel), and over a few years the hinges settle so the locking points drag on their keeps or miss them completely. The tell is check B above: if the door locks while you lift its weight, this is your fault. Composite doors hang on adjustable flag hinges, and bringing the slab back into line is a doorstep job from £90, usually no parts at all. Left alone it gets worse, because every forced lock-up strains the gearbox.
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If the handle will not lift even with the door standing open...
The multi-point gearbox has worn out or jammed, and the slab was never the problem. This is the same mechanism family a uPVC door uses (Winkhaus, ERA, Fullex, GU and the rest live behind composite handles too), and it is a like-for-like replacement from £145. Months of locking a door that needed an alignment adjustment is the most common way these die: the gearbox takes the strain the hinges should have been carrying. The mechanism-level detail lives on my door won't lock guide.
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If the key will not turn, or the door is jammed shut and will not open...
A key that will not turn in an otherwise happy door is the euro cylinder seizing: changed from £90, a 20-minute job, and worth upgrading to anti-snap while the door is apart. A composite door jammed shut with the hooks stuck out is a jammed gearbox, and forcing it is the expensive mistake: I can usually release it without damage first. The jammed-shut diagnostic, including what to do if you are locked inside, is on the door won't open page, and a stuck key is covered on key won't turn.
What national locksmith numbers will not tell you
A composite door that will not lock in hot weather has not broken, and a composite door that needs the handle slamming has almost never "worn out its mechanism". Both are alignment, both are fixed on the doorstep from £90, and both get quoted at £250 to £400 by people who diagnose over the phone with a price list instead of a question. The question is "does it lock in the morning?". Anyone who does not ask it is guessing at your expense.
Composite door won't lock in hot weather: the afternoon test
This is the composite-door fault, the one uPVC owners rarely see. A composite slab absorbs heat through its skin, and as it warms it expands. Darker colours absorb more, so an anthracite or black door on a south-facing elevation gets the worst of it. By late afternoon on a warm day the slab can have grown enough that the hooks and rollers no longer line up with their keeps, and the handle stops short of the top of its travel. The manufacturers say the same thing themselves: the swelling is temporary and the door contracts back to its normal size as the temperature drops.
8am
Locks first time
The slab is cool and at its normal size. Hooks meet their keeps cleanly, the handle lifts to the top, the key deadlocks without a fight.
4pm
Handle won't lift
Hours of sun have expanded the slab a few millimetres. The hooks now drag on or miss their keeps, so the handle jams part-way and the key will not turn.
If that pattern matches your door, it is thermal expansion. Nothing needs replacing.
What I actually do about it: ease the keeps (the metal plates the hooks land in have a few millimetres of adjustment) and set the flag hinges so the slab carries hot-day clearance. That visit is from £90, usually with no parts at all, and the door then locks in August the same as it does in January. What I will not do is plane a composite door like a joiner would a timber one: the slab is a GRP skin over a core, planing it wrecks the skin and voids the guarantee, and the door was only ever a few millimetres of adjustment away from behaving.
Composite door locks vs uPVC: what's actually different?
Good news first: almost nothing that matters to the repair. The lock parts on a composite door are the same families I fit to uPVC doors every week, which is why a composite door locksmith visit costs the same as a uPVC one. The differences worth knowing are all about the slab around the lock:
- Same lock parts: euro cylinder, multi-point gearbox (Winkhaus, ERA, Fullex, GU and the rest) and 92mm PZ handles are shared between composite and uPVC doors. A composite door lock replacement uses the same parts off the same van.
- Thicker slab, longer cylinder: a composite slab is typically around 44mm against a uPVC panel's roughly 28mm, so the cylinder is often a longer size. Fit a cylinder that pokes out and you have built in a snap weakness: measure it properly with my euro cylinder size guide, or better, go anti-snap while you are at it (the TS007 3-star guide covers which).
- Heavier slab, faster hinge wear: the weight that makes a composite door feel reassuring is carried by three flag hinges, and they settle sooner than uPVC ones. A composite door that gradually needs more of a slam to lock is dropping, not wearing out its lock.
- The skin swells in heat: the GRP skin behaviour covered above. uPVC doors move a little in heat too, but dark composite slabs are in a league of their own on south-facing elevations.
- The slab is a manufacturer part: locks, keeps, hinges and handles are locksmith territory. A genuinely warped, split or delaminated slab is a door-company job, usually under a 10-year guarantee. I will tell you which side of that line your door is on, and if it is guarantee territory I will say so rather than take your money.
Recent composite door call-outs
Three recent composite door calls across Wolverhampton, Cannock and Stafford: one heat expansion, one dropped door, one genuine gearbox failure. Real-pattern situations, real prices on the receipt, next to what the customer had been quoted elsewhere. Customer details lightly anonymised at their request.
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Friday 17 July 2026 at 5.45pm · Wolverhampton
Mrs Janet R., WV4, Wolverhampton
Anthracite grey composite front door, south-facing, would not lock every warm afternoon for a fortnight. Locked perfectly at breakfast. A door company had quoted her for a replacement locking mechanism and hinted the slab "might be on its way out".
Quoted elsewhere £340Paid to me £90Classic thermal expansion on a dark south-facing door. Eased all four keeps a touch and adjusted both flag hinges so the slab has hot-day clearance. Locked first time at the hottest point of the day when I tested it, and still locked cleanly that evening. No new parts, no new mechanism, and the slab is fine.
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Monday 13 July 2026 at 10.15am · Cannock
Mr Steve T., Cannock
Green composite front door, seven years old, needed the handle slamming and a knee against the door to lock at any time of day. He had been doing it for months and the handle had started to feel loose and gritty.
Quoted elsewhere £250Paid to me £90The heavy slab had dropped about 4mm on its hinges, so the hooks were dragging hard on every keep. Hex key into the flag hinges, slab back into line, keeps eased, and the handle lifted with two fingers again. Caught it just in time: the gearbox was starting to protest from months of forced lock-ups, and another winter of slamming would have killed it.
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Saturday 4 July 2026 at 8.30pm · Stafford
The Okafor family, Stafford
Composite back door would not lock at all: the handle flopped halfway up and the hooks would not throw. They had guests staying and did not want to leave the house unsecured overnight. Out-of-hours weekend call.
Quoted elsewhere £400 OOHPaid to me £230The multi-point gearbox had finally failed after (their words) "a couple of years of it being stiff". Like-for-like gearbox from the van, fitted out-of-hours in about 50 minutes, tested a dozen times open and locked. The stiffness had been an alignment issue all along: I set the hinges and keeps while I was in there so the new gearbox is not fighting the same drag that killed the old one.
The thermal behaviour above is documented by the composite door trade itself: Apeer, a composite door manufacturer, notes that "as the sun shines down on your doors, they will naturally swell and expand", and UK Composite Doors confirms dark-coloured doors on south-facing elevations are most susceptible, with the swelling resolving as temperatures drop. The alignment mechanics are the same ones the Master Locksmiths Association describes for multi-point doors generally: a door slightly out of alignment causes problems both locking and unlocking. My from-prices for the work above start at £90 for an adjustment visit and £145 for a like-for-like gearbox.
What customers say about door and lock call-outs
Verified Google reviews from real customers across Wolverhampton, Stafford, Cannock and the surrounding villages.
I got in touch with Sean as our back door lock had broken and we couldn’t lock the door at all. Sean came over really quickly and sorted the problem, he’s a lovely guy really chatty and friendly, and the communication was great. I would absolutely not hesitate to use him again in the future, thanks so much Sean!! Frankie Penkridge
Thankyou so much for the amazing review Frankie! It was my pleasure helping you today. Sean - Lockerfella Locksmiths 24/7.
Highly recommend fantastic service and Sean was a lovely honest polite chap Got us out of a mess and fitted a new lock very quick to arrive and completed the job brilliantly Thanks Sean
It was my pleasure to come out to Shifnal today and help you and Pete. Thankyou so much for your kind words. Sean - Lockerfella Locksmiths 24/7
Excellent service, very knowledgeable about the problem and left everything working okay Thanks Sean Robert Baggott Wolverhampton
You're more than welcome Robert. Real pleasure meeting you and assisting you today. Sean Lockerfella Locksmiths 24/7.
I Highly recommend Lockerfella Locksmiths Absolutely amazing price and what a friendly guy, from asking if he can come replace a lock on my front door, gave me the price upfront which was a big relief. To the communication on time of arrival, and informing me of the anti snap locks. Quick and easy swap over from old lock to new anti snap lock. I cannot fault anything he did at all. Very informative and professional and helpfulness. Thank you very much. .
It was an absolute pleasure assisting you today in Penkridge John. Thankyou for choosing Lockerfella Locksmiths 24/7. Sean ☺️
I got locked out of my house and called Sean from Lockerfella in Wolverhampton. I didn’t need his services in the end but he was so nice and was willing to help at such short notice. Thank you so much
You're more than welcome Georgia! I'm so pleased you managed to get in another way... and for free! Have a beautiful day. Sean ☺️ Lockerfella Locksmiths 24/7.
Absolutely fantastic! Came out to us in Stafford for an emergency lock repair and Sean was here in less than a hour! Sean is so polite and easy to have a chat to. Would definitely recommend to absolutely anyone! Best man for the job! Thank you ever so much again.
My pleasure guys. I'm glad I could help you both out. Sean - Lockerfella Locksmiths 24/7.
Sean answered promptly and was friendly. Nothing was too much trouble. Able to track his location to see when he would arrive in Stafford and excellent communication. Thank you!
Thankyou for the review Lucy. It was my pleasure. And I'm glad I gained a non-destructive entry for you. Sean - Lockerfella Locksmiths 24/7.
Got in touch with this company via WhatsApp on an evening. Sean was really accommodating and quick with communication. I booked him in straight away for our new house move to Penkridge. Came out on time, very clean and tidy work with some great advice on door safety. I would highly recommend using this company, what you are quoted is what you pay! Very reasonable prices too. The service has been exceptional.
Thankyou for your amazing review Rick. Absolute pleasure meeting you. I hope you have many happy years in your new home. Sean - Lockerfella Locksmiths 24/7.
Prices
What does composite door lock replacement cost?
The figures below are the floor prices for the composite door lock jobs I am called to most. They include attendance, diagnosis and labour, with no separate call-out fee, and the same parts and prices apply as for uPVC doors because the locks are the same families. I quote the all-in figure on the phone before I leave the van. The full price list with covers and affects sits on the dedicated pricing page.
- Alignment / hot-weather adjustment (hinges and keeps, no new parts) from £90
- Euro cylinder change (the composite door lock barrel, standard cylinder included) from £90
- Multi-point gearbox replacement (like-for-like) from £145
- Out-of-hours emergency (6pm to 8am, weekends, bank holidays) from £170
No VAT added on top. No call-out fee on any of these. Anti-snap and TS007 3-star cylinder upgrades are itemised separately so you can see exactly what each one costs. See the full price list and what each one covers →
About the locksmith
The locksmith answering your call
I'm Sean Hamilton. I run Lockerfella as a one-man-band. If you ring me about a composite door, the first thing I will ask is whether it locks in the morning, because that one question separates a £90 adjustment from a genuine gearbox job. I quote the all-in price on the phone before I leave the van. No call-out fee. No new mechanism for a door that just needed its hinges setting.
- 30+ years fascinated by locks. I've been picking, stripping and studying locks for the love of it for over 30 years. Lockerfella is what happens when a lifelong interest in how locks work becomes the day job.
- Trained and certified. Certificate of Locksmith Skills from A'Jam Locksmiths covering cylinder, mortice, padlock, wafer and euro lock picking, plus re-keying and mortice bypassing.
- Standard DBS checked, £1M insured, 12 months workmanship guarantee. Redacted DBS and insurance certificates are published on the About page, with originals available to view in person before work starts.
- One man, one van, one phone number. The phone rings on me directly. No call centre. No third-party fitter. If I quote you a price, that's the price you pay.
Common questions about composite door locks
Straight answers on composite doors that will not lock or open, hot-weather swelling, what a composite door lock replacement costs, and whether you need a locksmith or the door company.
Why won't my composite door lock?
Four causes cover nearly every composite door that has stopped locking. One: the slab has expanded in warm weather, so the locking points no longer line up with their keeps (dark doors on sunny elevations are the classic case). Two: the door has dropped a few millimetres on its hinges, which on a heavy composite slab happens sooner than people expect, and again the points miss their keeps. Three: the multi-point gearbox behind the handle has worn or failed, so the handle will not lift or the points will not throw. Four: the euro cylinder has seized and the key will not turn. The first two are adjustment jobs, often with no new parts at all. Tell me the symptoms on the phone and I will tell you which one you have before I set off.
Why won't my composite door lock in hot weather?
Because the slab itself has grown. A composite door skin absorbs heat, and on a hot day the slab can expand enough that the hooks and rollers no longer line up with the keeps in the frame, so the handle will not lift fully and the key will not turn. Dark colours absorb more heat, so anthracite or black doors on south-facing elevations are the worst affected. The giveaway is the pattern: the door locks first time in the cool of the morning and fights you in the afternoon. The expansion is temporary and the door usually locks normally again once it cools in the evening. If it happens every warm day, I can ease the keeps and adjust the hinges so there is enough clearance for the summer, which is a doorstep adjustment visit, not a new lock.
How much does composite door lock replacement cost?
It depends which part has actually failed, because "the lock" on a composite door is three separate parts. A euro cylinder change (the barrel your key turns in) is from £90 including a standard cylinder. A multi-point gearbox replacement (the mechanism the handle drives) is from £145. An alignment or hot-weather adjustment where nothing has actually broken is from £90 and often needs no parts at all. Out-of-hours attendance (6pm to 8am, weekends, bank holidays) is from £170. No call-out fee, no VAT on top, and I quote the all-in figure on the phone before I leave the van.
Are composite door locks the same as uPVC door locks?
Mechanically, yes. A composite door uses the same euro cylinder and the same multi-point gearbox families (Winkhaus, ERA, Fullex, GU and the rest) as a uPVC door, and the same 92mm PZ handles. What differs is the slab around them: a composite slab is thicker (usually around 44mm against 28mm-ish of a uPVC panel), so the cylinder often needs to be a longer size to sit flush, and the slab is much heavier, which wears hinges faster. So the parts I carry for uPVC doors fix composite doors too. The one thing to get right is the cylinder length, which is measured in two halves from the central screw: my euro cylinder size guide shows exactly how to measure it.
My composite door won't open at all. What should I do?
Stop pulling and work out which fault you have, because forcing a jammed composite door is how a repair becomes a full door job. If the key turns but the handle is dead and the door stays shut, the gearbox has jammed with the hooks thrown out, and it needs releasing rather than forcing. If the door unlocks fine but the slab will not pull open, it is binding: either heat expansion (try again when it has cooled) or dropped hinges. If you are locked out or locked in, ring me and tell me exactly what the handle and key are doing. I cover the full jammed-shut diagnostic, including what to do if you are stuck inside, on the door won't open page.
Do I call a locksmith or the door company for a composite door lock problem?
For anything lock-side (cylinder, gearbox, handle, keeps, hinge adjustment, getting you back in), a locksmith is the right call and usually the same-day one. For a slab that has visibly warped, delaminated or split, the door company is the right call, because a composite slab itself is a manufacturer part and most carry a 10-year guarantee that covers genuine warping. Where it gets cheeky is the overlap: I have seen door suppliers quote for a whole new door when the actual fault was an adjustment from £90, and national locksmith numbers quote a new mechanism for a door that just needed its keeps easing. My rule is simple: I fix what is actually broken, and if your slab is genuinely warped and still under guarantee I will tell you to use the guarantee rather than pay me.
Why is my composite door lock sticking?
A sticking composite door lock is usually one of three things wearing gradually rather than one thing broken. A dry cylinder wants a puff of graphite or a dry PTFE lubricant in the keyway (never oil or WD-40, which gum up the pins). A stiff multi-point wants the moving hooks and rollers along the door edge lightly greased about once every six months, which the manufacturers themselves recommend. And stickiness that gets worse through the day, or through the summer, is early-warning alignment: the slab is expanding or dropping and the points are starting to drag on their keeps. Caught at that stage it is a cheap adjustment. Ignored, it finishes the gearbox, because you are levering the handle harder every week until something inside lets go.
Ready when you are
Composite door still fighting you? Tell me the symptoms.
Tell me the door colour, which way it faces, whether it locks in the morning, and what the handle does. I will tell you on the phone whether it is heat, hinges, gearbox or cylinder, and the all-in price. No call-out fee. No deposit. No surprises.
Page last reviewed: . Reviewed by Sean Hamilton, the locksmith behind Lockerfella, under our editorial standards.