Updated
Window Will Not Close Properly
The sash catches on the frame, stands off at one corner, or needs shoving to shut.
Find a window fitter
What's happening?
A casement hangs on friction stays or hinges that are supposed to hold it square to the frame all the way through its arc. When it stops closing cleanly, the sash and the frame are no longer parallel. On uPVC the usual cause is a heavy sealed unit gradually pulling the sash out of square, or a friction stay whose arm has bent or whose slider has worn. On timber it is more often the frame or sash swelling with moisture, or a hinge screw that has lost its grip in soft wood. And on any material, a window in a wall that has moved — over a lintel, above a bay, or beside a settling extension — is being asked to close into an opening that is no longer the shape it was fitted to.
What usually causes it?
- Friction stay bent, worn, or with a seized slider, so the sash tracks off line as it closes
- Sash dropped at the outer corner under the weight of the glass, especially on wide or triple-glazed units
- Hinge screws pulled loose in timber, or hinge packers lost during a previous repair
- Timber sash or frame swollen from water ingress through failed paint on the bottom rail
- Sealed unit shifted on failed or missing setting blocks, throwing the sash out of square
- Debris, a proud fixing screw, or a build-up of paint in the rebate stopping the sash from seating
- Structural movement at the opening — a settling lintel or bowed frame in an older or altered wall
Is it dangerous?
A window that will not close is a security and weather problem, and it may be a safety one. If this is the designated escape window in a bedroom or loft room, both halves of the job matter — it must open for escape, and it must be capable of being closed and secured. There is also the collision consideration: an open sash over a path or in a corridor is a hazard, which is why the impact and collision guidance addresses open windows projecting into places people walk. If the window is stuck open above a walkway, that is a reason to act quickly.
Can I fix it myself?
You can clear the rebate of grit and flaking paint, check for a proud screw, and see whether the sash closes when you lift it slightly by the outer corner — a good, quick test that points straight at hinges or stays. Tightening a loose hinge screw in timber is reasonable. Forcing the sash, or planing timber to make it fit, is not: planing a swollen sash that later dries leaves a permanent gap, and forcing a uPVC sash puts the load into the corner welds.
When should you call a window fitter?
Call a window fitter when lifting the sash makes it close, when a stay is visibly bent, or when the gap between sash and frame is uneven along its length. Call urgently if the window cannot be secured overnight, if it is stuck open over a footpath, or if it is the escape window for a bedroom or loft room.
What will the window fitter actually do?
- Measure the sash-to-frame gap at each corner to establish which way the sash has moved
- Replace friction stays or hinges like for like, with the correct load rating for the glass weight
- Re-square the sash — repacking the sealed unit on new setting blocks where the glass has shifted
- Adjust the keeps so the locking cams engage once the sash sits square again
- Renew the perimeter gasket the sash has been closing against unevenly
- Report where the opening itself has moved, so a structural cause is fixed before the window is adjusted around it
Frequently asked questions
We’re happy to answer all your questions.
Need a window fitter?
Compare local window fitters on Tradehand — coverage areas, accreditations and phone numbers, no middleman.