A window that will not close is one of the few faults where the first instinct, leaning on it until it shuts, reliably makes things worse. Most of the time the window is being blocked by its own locking mechanism, and thirty seconds of checking saves both the damage and the call-out.
Start here: are the locking points thrown?
Multi-point locking works through a strip inside the sash edge carrying several mushroom shaped cams. When the handle is up, they stand proud and engage keeps on the frame. When the handle is down, they retract.
With the window open, turn the handle to the closed position and look along the edge of the sash. Every cam should sit flush. If any are still standing out, the mechanism has thrown while the window was open, which usually happens when someone turns the handle on an open window. Work the handle up and down a few times and they normally drop back. That is the whole repair, and it is the single most common answer.
The most common cause of a window that will not shut is a handle that was turned while it was open. Nothing is broken and nothing needs buying. Anyone who books a call-out before checking that has bought an expensive lesson.
Double Glazing Cost Calculator Team
If the cams retract properly
Then the mechanism is doing its job and the fault is alignment or hardware. Three candidates, in order of likelihood.
- The sash has dropped. If the window catches on the frame at the bottom corner, or the gap along the top is visibly uneven, a worn friction stay is letting the sash hang out of square. Our guide to adjusting window hinges covers what genuinely adjusts and what has to be replaced.
- Heat has swollen the frame. uPVC expands, so a window with little clearance can bind on a hot afternoon and close normally by evening. If the problem is seasonal and reverses on its own, that is clearance rather than failure. Do not have anything adjusted during a heatwave, because it will be wrong in winter.
- The keeps have moved or worn. The keeps are the slotted plates on the frame the cams engage with. If a cam is catching on the edge of its keep rather than dropping into it, the keep can be slackened, moved a millimetre or two and retightened.
If the handle spins with no resistance
That is a different fault and a more expensive one. Either the spindle has sheared or the gearbox inside the locking strip has failed. Fitting a new handle will not fix a failed gearbox, and it is worth knowing that before buying one: a new handle on a dead mechanism spins exactly like the old one.
Replacing a multi-point locking strip is a bigger job than any of the routine hardware swaps, because the strip runs the height of the sash and has to match the existing one on several dimensions. This is the fault most worth getting a proper diagnosis on rather than guessing at parts.
What each fix costs
| Job | Fitted cost | Notes |
|---|---|---|
| Reseat a thrown mechanism | £0 | Work the handle with the window open. No parts. |
| Reseal double glazing (per window) | £50–£100 | Specialist resealing where the gasket or seal has failed. |
| Replace a window handle | £45–£150 | Parts and labour; a quick job on most uPVC frames. |
| Replace window hinges | £100–£250 | Parts from around £27.50 a pair plus labour. |
Source: DGCC 2026 repair dataset, except the no-cost row. A failed multi-point gearbox is a larger job and is quoted per window.
If several windows are failing at once, total the work in the repair cost calculator before booking anything, and read repair against replace if the list is getting long. The window fault checker will walk the symptoms if you are still not sure what you are looking at.
When repairs stop being the answer
One jammed mechanism is not a reason to replace a window, and most of what is on this page costs nothing or very little. But if locking mechanisms are failing across a set of ageing windows, and the seals and sealed units are going the same way, the repair bill starts to approach the cost of doing the job properly. If you want to see that comparison for your own windows, tell us what you have and Leads 2 Trade will arrange quotes from installers covering your postcode.
Frequently asked questions
The four common causes are a locking mechanism that has thrown while the window was open, a sash that has dropped on a worn friction stay, a frame or sash that has expanded in heat, and a failed gearbox inside the locking strip. Checking whether the locking points are standing proud of the sash edge separates the first from the rest in a few seconds.
If the handle moves freely with no resistance, the spindle has sheared or the gearbox in the multi-point mechanism has failed. If the handle moves normally but the window will not pull shut, the locking points are probably not lining up with their keeps, which is an alignment problem rather than a mechanism failure.
Turn the handle back to the fully closed position while the window is still open. The locking points, the mushroom shaped cams along the sash edge, should retract flush. If they stay proud the mechanism has jammed part way and forcing the window shut will damage the keeps or the sash.
Yes, and it is a common summer call-out. uPVC expands in heat, so a window with very little clearance can bind on a hot afternoon and close perfectly the same evening. If a window only sticks in hot weather and is fine the rest of the year, that is a clearance issue rather than a fault.
It depends what failed. A handle is £45 to £150 fitted, hinges are £100 to £250 and a reseal is £50 to £100. A failed multi-point gearbox means replacing the locking strip, which is a bigger job than any of those, so it is worth diagnosing before booking anything.
Yes, and it should be treated as urgent rather than tidied away as a small annoyance. A window that will not engage its locking points is not secured by the handle alone, whatever it feels like from inside. It is also a point worth checking with your insurer, since some policies carry conditions about securing accessible windows.