Window Locks and Handles That Won't Close

In short:

Most window locking problems are alignment problems: the sash has dropped, a stay has loosened, or the frame has moved, so the catch no longer meets its keep.
Check with the window open first. If the handle and lock work freely open but not closed, the fit is the issue, not the lock.
Timber frames swell in the summer storm season; aluminium doesn't swell but collects grit and can bend. Each needs different care.
Burglar bars should leave at least one way out of each sleeping area, with the key close by but not in the lock. Some estates restrict external bars, so check the rules.

First, what kind of window is it?

Window types and where locking usually fails
Window	How it locks	Common failure
Side-hung casement	A handle turns a catch or espagnolette onto a keep; stays hold it open	Sash drops, so the catch rides over or under the keep
Top-hung or awning	Handle at the bottom; friction stays at the sides	Stays too loose or too tight; handle won't pull the sash in
Horizontal sliding (aluminium)	A latch or hook at the meeting rail, sometimes keyed	Latch and hook out of line; grit in the track
Timber sash or casement	Cockspur handle, stay with pin, or a keyed window lock	Swelling, paint build-up, loose screws in soft wood

Note whether the window has a key-operated lock as well as a handle, and find out where its key is before you need it.

Casement handles and stays

On a casement, the handle is only the last part of the job. The stays (the arms that let the sash swing and hold it open) carry the weight of the sash, and if they loosen or wear, the sash sags. A sagging sash meets the frame lower than it should, and the handle's catch misses its keep.

Many casements use friction stays, where a small adjusting screw sets how stiff the window is to open. One window maker's guidance is to adjust only slightly and to make the same adjustment on the opposite stay. A window that's too loose can blow open in the wind; one that's too stiff strains the handle.

A handle that turns freely without moving the catch has usually lost its grip on the spindle, or the spindle or gearbox inside has worn. That's a part replacement, not an adjustment.

Illustration A dropped casement sash, exaggerated for clarity. The handle and lock may be perfectly sound; the catch simply no longer meets the keep.

Sliding windows

Horizontal sliders lock where the two panels overlap. The latch on one panel has to meet the hook or keep on the other, so anything that changes the height or position of a panel stops it locking:

grit, leaves and dead insects in the bottom track, especially after storms;
worn or broken rollers that let a panel sit lower;
a bent track or frame, sometimes from someone forcing the window;
loose screws on the latch or keep.

Clean the track with a soft brush and a damp cloth, then slide the panel slowly and watch the latch as it reaches the keep. If one rides over the other, the panel height or keep position needs adjusting.

Aluminium and timber need different care

Timber takes up moisture and swells in humid weather, so timber windows on the Highveld often bind during the summer rains and loosen in the dry winter, much as doors do; our article on doors and locks sticking after summer rain explains why. Paint build-up on the edges and screws pulling out of softened wood are common too.

Aluminium doesn't swell, but it collects grit, its small fittings can corrode, and thin sections bend if a window is forced. ASSA ABLOY's care guide notes that warped windows and distorted frames put extra load on other components and shorten their life. It recommends cleaning hardware with mild detergent in warm water, rinsing well, avoiding strong solvents, keeping cleaning fluids out of the lock, and not using silicone-based lubricants, which turn tacky.

For any lubricant on window hardware, use what the maker specifies, sparingly.

Safe checks before you call

Open the window and work the handle or lock. Smooth when open but stiff when shut means a fit problem.
Close the window slowly and watch where the catch meets the keep. Is it high, low or to one side?
Look along the frame for rub marks or scraped paint.
Check that the screws on the handle, keep and stays are tight. Don't overtighten into soft timber.
On a casement, see whether the sash drops when you lift and lower it slightly on its stays.
On a slider, clean the track and check that the panel runs level.
Try the key in any window lock. If it's stiff in every window, the keys may be worn.
Check the burglar bars: do the openable sections still open, and can you find their keys?

Don't force a handle that won't turn, lever a sash shut, or tighten one stay hard to stop a draught. Each can bend a stay or break a handle gearbox.

Burglar bars and getting out in an emergency

Burglar bars help keep intruders out, but fixed bars on every window can trap the people inside during a fire. Trellidor, a South African maker, suggests choosing a window in a bedroom or bathroom to have an openable barrier and deciding where to keep its key: accessible, but not obvious. Don't leave the key in the lock, where it can be reached through broken glass.

In an estate, check the rules before adding bars. Some estates restrict what can be fitted on the outside; one Centurion estate's published architectural rules list external burglar bars among prohibited window items. If your estate is like that, look at what is allowed inside the window, and at better window locks.

For a whole-house plan, including doors and sliders, see upgrading the locks in an estate home.

When to call a locksmith, and what helps

Call when a window won't lock and you need it secure tonight, a handle has broken, window lock keys are lost, a burglar bar padlock or gate lock has seized, or windows were damaged in a break-in. We repair and replace window handles and locks as part of our residential locksmith service, and after a break-in our break-in repairs service covers making openings secure again.

We don't cut or copy keys, so lost window keys usually mean new window locks. As a mobile locksmith in Centurion, we work 24/7. There's an R250 call-out fee, you get a quote on site before any work starts, and you can pay by EFT, cash or card.

Helpful details:

How many windows are affected, and which rooms.
Frame material: aluminium, timber or uPVC.
A photo of the handle or lock and one of the whole window.
Whether the window has a key lock, and whether you have the keys.
Whether burglar bars or security screens are fitted, and whether they open.

Questions

My window handle turns, but the window doesn't lock. Why?

Either the handle has lost its grip on the spindle or catch inside, or the sash has dropped so the catch misses the keep. Close the window slowly and watch the catch. If it moves but misses, it's alignment; if it doesn't move at all, the handle or gearbox needs replacing.

Can you supply spare keys for my window locks?

No, we don't cut or copy keys. If window lock keys are lost, we replace the locks, which come with new keys from the maker. It's also a chance to fit locks that use the same key throughout, if the maker offers that.

Should every window have openable burglar bars?

Not necessarily every window, but every sleeping area needs a way out in an emergency. A common approach is one openable barrier in each bedroom, with its key kept nearby but out of reach from outside. If you live in an estate, check its rules on bars first.

Need a locksmith to look at it?

If this hasn't solved the problem, our residential locksmith service covers it. We're a mobile locksmith in Centurion, so we come to your door.

Sources and further reading

Everest: My window is too stiff or too loose when opening — friction stays control how stiff a casement opens; adjust slightly and equally on both stays; loose windows can blow open
ASSA ABLOY South Africa: Product care and maintenance (PDF) — warped windows and distorted frames load other components; mild detergent cleaning; avoid strong solvents and silicone-based lubricants
Trellidor: Emergency escape security barriers essential — choose a bedroom or bathroom window for an openable barrier; keep the key accessible but not obvious
Copperleaf Country Estate: Architectural and development rules (PDF) — external burglar bars listed among prohibited window items
Wikipedia: Highveld — summer rainy season with afternoon thunderstorms
WOODweb: The movement of wood — wood swells and shrinks across the grain as its moisture content changes