Window Will Not Close or Lock Properly? Work Through This First

First, make it safe

If the window is on a ground floor, above a flat roof or otherwise reachable, treat it as an insecure opening until it is fixed. Most insurers expect windows to be secured when a property is unoccupied, and a window that will not lock is exactly the sort of detail that matters after a break in.

In the short term, closing it onto its gaskets and keeping it closed is better than leaving it ajar. Do not wedge or screw a sash shut in a way that would stop it opening in a fire, especially in a bedroom where the window may be an escape route.

Look for the obstruction

Before assuming a mechanical fault, check the simple physical causes, because they account for a good share of these calls. Something in the frame rebate stops the sash seating properly and the handle then will not throw.

Close the sash slowly and watch where it makes contact. Look for grit, stones, an old gasket that has crept out of its channel, a nail or screw left in the rebate, paint build up, or a bird nesting behind a trickle vent. Cleaning the rebate and the keeps out properly is the first job, and it is often the last one too.

• Grit, stones or debris in the frame rebate
• Gasket crept out of its groove and bunched in a corner
• Paint or sealant build up on the rebate face
• Debris packed into the keeps in the frame
• Objects on the sill inside preventing the sash seating

Then check whether the sash is square

With the sash closed as far as it goes, look at the gap around it on all four sides. If it is even, the sash is sitting correctly and the fault is likely in the locking mechanism or the keeps. If the gap is wider at the top than the bottom, or tight on one corner only, the sash has dropped or racked and that is why the locking points will not meet.

A dropped sash is usually a hinge story rather than a lock story. Worn or corroded friction stays let the sash sit low, and the cams then arrive below their keeps. Adjusting or replacing the stays brings it back square and the handle often works normally again without touching the mechanism.

Test the mechanism itself

Open the window and turn the handle slowly while watching the edge of the sash. Every cam or mushroom bolt should rotate or extend evenly and smoothly. If some move and others do not, the strip has a fault along its length. If none move, the drive between the handle and the gearbox has gone. If they all move freely but the window still will not lock when closed, the keeps in the frame are the mismatch.

Light lubrication of the cams and keeps, then retesting, is worth doing at this stage. If it improves, the mechanism was dry. If nothing changes, the alignment or the mechanism needs proper attention.

• Watch every locking point move with the sash open
• Lubricate the cams and keeps, then retest
• Check the keeps are secure and not worn oval
• Note whether the handle feels loose, gritty or solid
• Stop before applying real force to the handle

Tilt and turn and other specialist gear

Tilt and turn windows have a more involved mechanism with a specific sequence, and they can be knocked into a mis handled state where the sash is held in two positions at once and will not close. This is a known behaviour rather than a breakage, but resetting it needs care and the correct sequence for the hardware in question, so it is worth having it done properly rather than forcing the handle round.

Similarly, easy clean hinges, fire escape hinges and restrictors all behave differently, and a restrictor that has jammed can present exactly as a window that will not close.

Deciding between repair and replacement

Most of these problems are repairable while the frame is sound, and that is usually the right route. Adjustment, new stays, new keeps or a matched mechanism will return the window to normal use for a fraction of a replacement.

Where we would talk about a new window is when the frame or sash has distorted, when welded corners have opened, when the profile is too worn to hold fixings, or when the hardware pattern is no longer available. Multiple windows on the same elevation showing the same fault is another point where it becomes a value question rather than a repair question.

Getting it dealt with

We survey free of charge across the Wirral, Chester and around thirty miles from base. Because a window that will not lock is a security matter, it is not one to leave sitting on the list, and we would far rather look at it than have you force a handle and turn it into a bigger job.

Common questions

My window will not lock. Is that an insurance problem?

It can be, because many policies expect windows to be secured when a property is unoccupied, so a window that cannot be locked is worth treating as a priority.

Why will my window not pull up tight any more?

Common causes are debris in the frame rebate, a gasket that has crept out of place, or a sash that has dropped on worn hinges so the locking points no longer line up.

Should I force the handle to get it locked?

No. Forcing the handle puts the load into the gearbox, which is the part most likely to shear, and that turns an adjustment into a mechanism replacement.

Can I wedge or screw the window shut in the meantime?

Avoid anything that prevents the window opening in an emergency, particularly in bedrooms where it may be an escape route. Keeping it closed on its gaskets is the safer stopgap.

My tilt and turn window is stuck between positions. Is it broken?

Often not. Tilt and turn gear can be knocked into a mis handled state that holds the sash awkwardly, and it needs resetting in the correct sequence rather than forcing.