A window that will not shut properly is more than an annoyance; it is telling you something, and usually what it is telling you is about the frame rather than the glass. When a sash sticks, rattles or refuses to latch, people often assume the window is just old and leave it, or they reach for a plane or a tin of paint. But the cause behind it is what decides whether this is a quick fix or a sign the window is on its way out. uPVC Windows Expert supplies and installs replacement windows across New South Wales, and this article helps you work out what is actually going on with yours, so you know whether you are looking at a minor adjustment or a frame that has had its day.
A window that will not close is usually a frame problem rather than a glass problem. If the sash binds along one edge, latches only when lifted, or shows daylight at the sill, the frame has moved, or the sill has deteriorated. If the sash still sits square and only the handle or hinge is out of line, the frame is sound.
Work out what is actually moving
Before you can judge how serious it is, you need to work out what is physically going on, and you can learn most of it with a few simple checks. Open and close the window slowly and watch and feel where it catches.
Does the sash bind at the top, the bottom, or one side? Pay attention to where it meets resistance as it closes. A sash that rubs or jams along one particular edge tells you something has shifted out of true, and where it binds is a clue to what has moved.
Does it latch if you lift it? Try gently lifting the sash as you close it and see whether it then latches when it would not before. If lifting the sash lets it close and lock, the sash has dropped out of alignment, which points to the frame or the way the sash is sitting rather than the glass.
Is there daylight at the sill? With the window shut, look along the bottom edge where the sash meets the sill, ideally with a light on the other side. If you can see daylight through a gap at the sill, the seal between the sash and the frame has failed, which usually means the frame or sill has moved or deteriorated.
Those three checks- where it binds, whether lifting helps, and whether there is a gap at the sill- tell you most of what you need before anyone looks at it professionally. They point to whether you are dealing with hardware that has slipped or a frame that has gone.
When it is the hardware
The least serious cause, and the best-case outcome, is that the frame is sound and only the hardware has gone out of alignment. The moving parts of a window- the hinges, the keeps (the catches the handle locks into), and the handle itself- can shift, wear or loosen over time, and when they do, the window can stick or fail to latch even though the frame around it is perfectly fine.
The telltale sign of a hardware problem is that the sash itself still sits square and true in the frame, and the issue is only that the handle, hinge or keep is not lining up as it should. The window has not warped or dropped; the mechanism has just drifted out of adjustment.
This is the good news scenario, because it means the window structure is healthy and only the mechanism needs attention. A hinge that has sagged, a keep that needs realigning, or a handle that has worn are all about the hardware rather than the window itself. The point to take from it is diagnostic: if the sash still sits square and only the moving parts are out of line, the frame is not the problem, and you are not looking at a replacement on account of this.
When it is the frame
The more serious cause, and the more common one on an ageing window, is that the frame itself has failed, and this is where the window is genuinely telling you it is near the end. Frames fail in material-specific ways.
A timber frame moves with the weather. Timber absorbs moisture and swells in wet, humid conditions, then dries and shrinks again, and over years of that cycle the frame distorts, so the sash that fitted neatly now binds in the wet season and rattles in the dry. An aluminium frame can distort over time too, going out of square so the sash no longer seats properly. And the sill, the bottom of the frame, is where water sits, so it tends to rot or deteriorate from the bottom up, which is exactly why daylight appears at the sill as the seal there goes.
Here is the thing people waste money on: painting over it, or planing the binding edge, buys you about one season. Planing a swollen timber frame removes material so it closes again now, but the timber swells back next wet season, and you have lost frame material permanently. Repainting a deteriorating sill hides it for a while but does nothing to stop the rot underneath. These are symptom treatments, not fixes, because the frame is going to keep moving or keep rotting. When the frame has failed, replacing it with a stable material is what actually solves it, which is why uPVC window frames supplied and installed across NSW are chosen to replace timber and aluminium that has distorted, since uPVC holds its shape through the same weather that moved the old frame.
Repair or replace
So how do you decide? The brief version is a single test, and it cuts cleanly. Look at whether the sash still sits square in its frame.
If the frame has moved, if the sash binds along an edge because the frame is out of true, or the sill shows daylight or has deteriorated, then the frame is the problem. A frame that has distorted or a sill that has rotted will not be put right by adjustment, because the structure itself has failed, and that points to replacement. No amount of hardware tinkering fixes a frame that has lost its shape.
If, on the other hand, the sash still sits square and true and only the handle, hinge or keep is out of line, then the frame is sound, and the window is not failing. That is not a replacement situation, it is a hardware one.
So the decision is cleaner than people fear. Square sash plus misaligned hardware means the frame is fine. An out-of-square sash, binding frame or a gone sill means the frame has failed. When it is the latter, replacement is usually the honest answer, and a modern double glazed uPVC windows and doors replacement also lifts the window’s comfort and performance well beyond what the old frame ever offered, so the forced change becomes an upgrade.
The frame fails first
The lesson in a window that will not close is almost always the same: the frame is the part that fails first, and the sticking, rattling or gapping is how it tells you. The glass is usually fine, and the hardware, when that is the culprit, is the easy case. It is the frame distorting or the sill rotting that turns a window into a replacement, and the sits-square test is how you tell the two apart in a minute. If your window is sticking and you are not sure which it is, book a free measure and we will tell you honestly whether your frames need replacing.
Frequently Asked Questions
Can a swollen timber window frame be fixed?
Planing the binding edge or repainting treats the symptom, not the cause, so it closes again for now but the timber swells back with the next wet season. Because the frame keeps moving with the weather, these fixes buy a season rather than solving it, and the problem returns.
Does a window that will not close lose much heat?
It can, and the gap at the sill is usually the main culprit. When daylight shows at the bottom of the sash, that same gap is an open path for draughts, letting warm air out in winter and hot air in during summer, which makes the room harder and costlier to keep comfortable.
How do I tell the frame from the hardware?
Use the sits-square test. If the sash still sits square and true in the frame and only the handle, hinge or keep is out of line, it is a hardware issue and the frame is sound. If the sash binds or the sill shows daylight, the frame has moved and it is the frame.