Top hung window not closing properly is one of the most common aluminium window complaints, and in most cases it is not a broken window. It is dirt, adjustment, or a stay that has stopped travelling evenly.
Most closing problems are prevented by regular aluminium window maintenance.
This guide works through the causes in the order we actually find them, so you can check the cheap things first.
Ready to price your opening? Our top hung aluminium windows page lists every standard size with its price.
Start by looking along the seal
Close the sash as far as it will go and look along the gap between sash and frame from the side.
If the gap is even all the way round but the handle will not throw, the problem is the lock or the keep.
If the sash stands off at one corner only, something is holding it there, and that is a mechanical obstruction rather than a lock fault.
If it stands off evenly along one whole edge, suspect the stays.
Clean the rebate before anything else
The frame rebate is the channel the sash closes into. It collects grit, cobwebs, insect nests and, in older windows, layers of overspray paint.
Any of that will hold a sash off its seal by a millimetre or two, which is all it takes.
Clean it out with a brush and a vacuum, then try the sash again. This resolves a surprising share of cases where a top hung window is not closing.
Check the friction stays
A top hung sash hangs on two friction stays, one at each side, and they have to travel together.
If one stay is bent, seized or has loosened at its fixings, the sash will close crooked and meet the frame on one side before the other.
Open the window and watch both stays as you close it. If one lags, that is your answer.
A stay that is stiff part-way through its travel is usually dirty rather than failed. Clean the channel and lubricate it.
A stay that is visibly bent needs replacing, and stays are replaced in pairs so the sash stays square.
Check the handle and keep
If the sash meets the frame all the way round but the handle turns without pulling anything in, the cam is missing the keep.
The keep is the plate on the frame the lock engages with. It can work loose or the sash can settle slightly, leaving the cam passing above or below it.
That is an alignment job, not a replacement.
Has the sash dropped?
A dropped sash catches the frame on its closing edge, usually at the bottom corner furthest from the hinge side.
You will often see a witness mark where the two have been rubbing.
Dropping is caused by loose stay fixings far more often than by a failed stay. Check and tighten the screws before assuming the worst.
If the fixing holes have pulled through the profile, the stay needs relocating or the sash needs replacing.
When it is the frame, not the window
Occasionally the opening itself has moved, and the frame with it.
Measure the diagonals of the frame. If they differ noticeably, the frame is out of square and no amount of adjustment at the sash will fix it properly.
That is the point at which replacement becomes the honest answer rather than repair.
Repair or replace?
Repair while the frame is straight, the glass is intact, and parts are still available for the stays.
Replace when the frame is corroded or distorted, the rebate is damaged beyond sealing, or the hardware is obsolete with nothing to match.
If you are replacing, see top hung windows for how they work and aluminium window sizes for measuring.
Coetz supplies aluminium windows and doors nationwide across South Africa. We do not install or carry out repairs; the checks above are for you or your installer.
SAGGA, the South African Glass and Glazing Association is the industry reference body.
A top hung window not closing in winter but fine in summer
Seasonal behaviour usually points at the seal rather than the hardware.
A compression gasket hardens as it ages and stiffens further in cold weather, so the sash needs more force to pull in.
If the window closes with a firm push but not a light one, and it is worse on cold mornings, replace the seal before touching the stays.
A top hung window not closing after painting
This is common in older properties where the reveal has been repainted around the frame.
Paint runs into the rebate and onto the seal, building up a layer that holds the sash off.
Scrape the rebate clean and check the seal has not been painted over. A painted gasket loses its compression entirely.
A top hung window not closing after a storm
Wind catching an open sash is the usual way stays get bent.
If the window was open during high wind and has not closed properly since, inspect both stays for distortion before anything else.
This is also the argument for restrictors on exposed elevations.
Quick reference
Top hung window not closing at one corner — something is caught in the rebate, or a stay has dropped.
Top hung window not closing evenly along an edge — the two stays are not travelling together.
Top hung window not closing but the handle spins — the cam is missing the keep.
Top hung window not closing since a repaint — paint build-up in the rebate or on the seal.
Top hung window not closing: at a glance
Clean first. A top hung window not closing is most often a rebate full of grit or paint.
Watch both stays. Uneven travel is the next most common cause.
Check the keep. If the handle spins freely, the cam is missing it.
Then measure the frame. Out-of-square diagonals mean the opening has moved.
If the window has to be replaced
See top hung windows for how the sash and stays work, and aluminium window sizes for how to measure the opening.
Browse the range under aluminium windows or request a quote.
Coetz supplies aluminium windows and doors nationwide across South Africa. We do not install or carry out repairs, so the checks above are for you or your installer.
For glazing standards and industry guidance, SAGGA, the South African Glass and Glazing Association is the reference body in South Africa.
Frequently asked questions
Why is my top hung window not closing on one side only?
One stay is travelling differently from the other, or something is caught in the rebate at that corner.
Can I fix a top hung window not closing myself?
Cleaning the rebate and tightening stay fixings are straightforward. Replacing stays is a job for someone comfortable with the hardware.
Should stays be replaced in pairs?
Yes. Mismatched stays make the sash close out of square.
The handle turns but nothing happens. What is wrong?
The cam is missing the keep. It needs realigning.
How do I know if the frame is out of square?
Measure both diagonals of the frame. A noticeable difference means it has moved.
Handle questions: see aluminium window handles.
Routine care: see how to clean top hung windows.
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