Guide
Woking uPVC Door Will Not Lock? How to Tell Which Fault It Is
If the door cannot be secured tonight, call 01483 377197, at any hour.
Before deciding whether this needs a call tonight or a booked visit, lift the handle with the door standing open, then try again with it shut: the difference between those two attempts names the fault. A uPVC door that will not lock usually comes down to misalignment, a fault in the locking mechanism, or movement caused by temperature.
A door that locks when open but not when shut is almost always an alignment problem, with the locking points no longer meeting the frame. A handle that is stiff or will not lift in either position points at the gearbox or another part of the multipoint mechanism. And a door that started failing during a heatwave or a cold snap may need nothing done to it at all. This guide from Woking Locksmith takes each in turn.
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Start With the Open Door Test
Open the door wide, lift the handle, and watch the hooks and rollers along the door edge. If the handle lifts and the hooks throw with the door open, the mechanism is working and the problem lies where the door meets the frame. If the handle will not lift even with the door open, the frame has nothing to do with it. Never force the handle during the test: if it does not lift easily, that is the result, not a reason to push harder.
| What you observe | What it means | What to read next |
|---|---|---|
| Handle lifts with the door open, sticks when shut | Mechanism works; door and frame no longer line up | The alignment section below |
| Handle will not lift with the door open either | The fault is inside the door, usually the gearbox | The gearbox section below |
| Door will not open at all | A different problem | A uPVC door that will not open |
The Handle Lifts With the Door Open but Not When It Is Shut
Here the mechanism is doing its job and the door has stopped lining up with the frame. Lifting the handle swings hooks and rollers out of the door edge, and they have to enter the keeps on the frame. If the door has dropped, swollen or shifted, one or more hooks strikes metal instead of the slot and the handle stops part way. Adjustment may solve the problem without replacing the lock. An inspection is still needed to rule out a fault in the mechanism.
With the door open, look for:
- A bright rubbed mark or shiny patch on a keep: that is where a hook is catching, and it tells you which keep is out.
- Uneven gaps around the door in the frame.
- Resistance as the door closes, or a door that needs pushing before it will latch.
The order of work follows from this: move the keep that is catching before you touch a hinge.
The Handle Will Not Lift in Either Position
This time the frame is not involved, so the problem sits inside the door. With the door wide open there is nothing for a hook to catch on, so a handle that still refuses to lift is being stopped by the mechanism itself, usually the gearbox at its centre. Two versions sound alike to a householder but are different jobs:
- The handle lifts part way and stops hard: something in the mechanism is binding or jammed.
- The handle lifts with no resistance and achieves nothing: usually something inside has sheared, and the handle is no longer connected to anything.
For the full picture, see what goes wrong inside a uPVC lock mechanism, and if the key itself will not turn, our guide to a key stuck in a lock. The one thing that makes either version worse is forcing it, covered further down.
If It Began in a Heatwave or a Cold Snap
If the door locked perfectly last month and stopped during a hot spell, it may not have a fault at all. The pattern is recognisable: the door is worse in the afternoon than in the morning, worse on a sunny side of the house than a shaded one, and it recovers by itself when the weather turns.
How Far a uPVC Door Actually Moves
uPVC moves about 1.2mm per metre for every 20 degree change in temperature. Tangram Technology gives the linear expansion coefficient of PVC-U as 0.00006 per degree Celsius, and its worked example takes a 1,000mm length through a 20 degree rise to arrive at 1.2mm. Applying that coefficient to a door leaf around 2m tall gives movement in the order of 2.4mm over the same swing; that is our calculation from Tangram's coefficient, not a figure Tangram published for doors.
Tangram also puts PVC-U at roughly five times the thermal expansion of steel and two and a half times that of aluminium.
| Material | Movement on 1,000mm over 20 degrees |
|---|---|
| PVC-U | About 1.2mm (Tangram worked example) |
| Aluminium | About 0.5mm (calculated from Tangram's ratio) |
| Mild steel | About 0.24mm (calculated from Tangram's ratio) |
The mechanism behind the seasonal fault is reasoning rather than a quoted claim: the frame is held by the wall around it and the leaf is not, and a leaf in direct sun runs warmer than a shaded frame. It is the difference between the two that moves the hooks off their keeps, not simply the air temperature.
Why Adjusting a Hot Door Creates a Winter Problem
A 2m leaf moves in the order of 2.4mm across a 20 degree swing, while the compression adjustment on a flag hinge gives about 2mm in total, according to the Double Glazing Cost Calculator adjustment guide. The setting that decides whether the hooks reach their keeps has less travel than the seasonal movement. A door wound in to lock at 30 degrees can be tight, or worse, at 5 degrees, and the complaint comes back in autumn the other way round. In a hot spell:
- Try the door again in the evening, once the leaf has cooled.
- Compare it with any door on the shaded side of the house, and only treat it as a fault if it still will not lock after the weather has turned.
This is a reason to wait, not a claim that adjustment never helps. A door that has never locked properly, or fails in every season, has a real alignment fault and belongs in the next section. Do not assume a door that only latches is secure: the latch can hold it shut without the multipoint system engaging, so if it cannot be locked properly, get help promptly. A failing lock rarely means a new door, because alignment, a faulty cylinder or part of the mechanism can often be repaired on their own. If the cylinder itself is the issue, see changing the cylinder on a uPVC door.
Temperature changes make uPVC expand and contract slightly, which alters how the door sits in its frame. Premier Windows says uPVC frames may expand slightly above around 25 degrees and contract back to their original size once the temperature falls below 23 degrees, and that darker colours such as anthracite grey and black expand more noticeably because they absorb more heat. Treat those thresholds as that installer's guidance rather than a standard. Even a small shift in the door or frame changes how the hooks, rollers and bolts meet their keeps. A door that stays hard to lock whatever the weather, though, may have a genuine alignment or mechanism fault.
Adjust the Keeps Before You Touch the Hinges
If one hook is catching one keep, move that keep: a hinge moves the whole door, while a keep moves only the part that is wrong. The keeps are the metal plates on the frame that receive the hooks, rollers or bolts, and they sit on slotted screw holes. The Double Glazing Cost Calculator adjustment guide says to slacken the screws, shift the keep two or three millimetres in the direction needed, and retighten. Mark the old position in pencil first so it can go back.
What Each Hinge Type Can Correct, and by How Much
The answer depends on which of three hinge types your door has, and you can tell by looking. Flag hinges are the commonest and adjust three ways: height with about 4mm of travel, lateral about 5mm either way, and compression about 2mm, usually with a 5mm allen key and sometimes a 4mm. Butt hinges, found on older doors, give up to 2mm sideways through two Phillips screws and height through an allen screw beneath the top cap, though some do not adjust at all. T-hinges on heavier doors offer height and lateral only, often by slackening the fixing screw and repositioning, and compression is rarely available.
If the door needs more movement than its hinge type can give, no amount of turning will fix it, and the fault lies elsewhere.
How Far to Turn Anything Before Testing
Turn a quarter to half a turn, then close the door and try it, every single time.
- Height: a quarter to half a turn at a time, adjusted across all three hinges together rather than one, because winding up a single hinge twists the leaf instead of lifting it.
- Compression: no more than 45 degrees at a time.
- Test between every adjustment, rather than making several turns on one hinge.
All of this comes from the Double Glazing Cost Calculator adjustment guide. Stop if two rounds of small adjustments have made no difference, and note what you changed, because whoever looks at it next needs to know where the door started. Stopping there is sensible, not a failure. For what door and lock work costs, see locksmith prices in Woking.
The distinction that decides the job: one hook missing is a keep adjustment; several hooks missing together means the door as a whole has moved, which is a hinge job. Before adjusting anything, check for loose fittings, rub marks and uneven gaps, because adjusting without knowing the cause can leave the door harder to close or secure. Never drill, file or enlarge a keep.
| Hinge type | What it adjusts | How much (approx.) | Tool |
|---|---|---|---|
| Flag hinge | Height, lateral, compression | Height about 4mm; lateral about 5mm each way; compression about 2mm | Usually a 5mm allen key, sometimes 4mm |
| Butt hinge | Lateral, height | Up to 2mm sideways; height through a screw under the top cap; some do not adjust | Two Phillips screws; allen key for height |
| T-hinge | Height, lateral | Compression rarely available | Slacken the fixing screw and reposition |
Figures are from the Double Glazing Cost Calculator adjustment guide. If adjustment is not enough, lock repair is often the next step rather than replacement.
When It Is the Gearbox Rather Than the Alignment
The gearbox is the small unit at the middle of the metal strip in the door edge, and both the handle and the key drive it. It passes movement from the handle and key to the hooks, rollers or bolts, takes the load of every lift of the handle, and is the part that wears. When it fails, the handle either jams part way or goes slack.
What happens next:
- Gearbox only or whole strip: on many doors the gearbox can be replaced by itself; on others the whole strip has to come out. Which applies depends on the mechanism, not on how bad the fault feels.
- Identify and match: the mechanism has to be identified and matched before a replacement can be fitted, so it is a measuring exercise before a fitting one. [CLIENT TO CONFIRM: whether mechanisms and gearboxes are carried as van stock]
Do Not Force the Handle
Forcing a handle against a jammed hook turns a small job into a large one. The handle is a lever, and the gearbox is the weakest link in the load path. Push hard on a handle whose hooks cannot enter their keeps and the force goes into the gearbox rather than the door; a gearbox that worked before the push may not work after it.
The same mistake has a second form: turning the key harder when it will not turn, which loads the cam and can damage the cylinder or bend or snap the key in the lock.
- Do not force the handle, even if it moved slightly before.
- Do not force the key.
- Do not keep slamming or pushing the door to make it line up.
Instead, stop, note what the door was doing, and leave it in whichever state is safest.
How to Leave the Door Secure Until It Is Fixed
A door that shuts and latches but will not throw its hooks is closed; a door that will not shut at all is open, and the two carry different risks.
Check:
- Whether the key still deadlocks the door once it is pulled to. On some doors the cylinder throws a bolt independently of the hooks, so the door can be locked even when the handle will not lift fully.
- Whether any second lock on the door still works.
Do not:
- Wedge, tie or prop the door as a substitute for a lock.
- Rely on the latch alone as if the door were locked.
- Leave a key in the inside of the cylinder where a glazed panel is within reach of it.
A locksmith can often get a door locking on the visit even when the full repair waits for a part [CLIENT TO CONFIRM: whether temporary securing then a return visit is offered]. A door that cannot be made secure at all is an emergency rather than a job for next week: an emergency locksmith can attend at any hour, and if the door or frame is damaged, see emergency boarding up.
Get the Fault Diagnosed
Tell us what the handle did with the door open and what it did with the door shut, and we can usually name the likely fault from the description.
Have ready: both test results, the door material, whether it started in a hot or cold spell, and a photograph of the door edge with the handle lifted.
There is no call-out charge at any hour, emergency calls are answered 24 hours a day every day of the year, and the price is given on the call from what you describe. [PROVIDER PACK: DBS check status of technicians] [PROVIDER PACK: public liability insurance details]
Describe the Fault and Get a Price: 01483 377197
uPVC Door Locking Questions
How do I know if the gearbox has failed?
It may be faulty if the handle jams, feels unusually loose, or fails to move the locking points even with the door open. Those signs suggest a problem inside the mechanism rather than friction between the door and frame.
Why does my door lock when open but not when closed?
That usually means the door or its locking points are not meeting the frame keeps correctly. The hinges, keeps or door position may need assessing; avoid forcing the door into place repeatedly.
Is my door secure if it shuts but will not lock?
You should not assume so. The latch can hold the door closed without the multipoint locks engaging, so arrange help promptly if it cannot be locked.
Can heat stop a uPVC door locking?
Yes. Heat can make uPVC parts expand slightly, which can upset the alignment between the locking points and the keeps. If the problem disappears in cooler weather, that is a strong clue.
Should I spray lubricant in the lock?
Lubrication may help with stiffness caused by friction, provided the manufacturer recommends it. Before applying any product, check that it is approved for your particular lock.
I rent my home. Who fixes the lock?
Repairs to faulty external doors and locks in rented homes in England generally fall to the landlord, except where the tenant caused the damage. Let the landlord know as soon as possible, making clear if you cannot secure the property. For more on home lock work, see our.