In short:
- A door that won't latch is nearly always one of three things: the latch and its strike plate no longer line up, the latch itself is sticking or broken, or something is stopping the door from closing far enough.
- Where the latch touches the strike plate tells you which way the door has moved. A little chalk or lipstick on the latch shows you.
- Loose or worn hinges are a common hidden cause, especially the top hinge on a heavy door.
- Seasonal swelling and shrinking of timber doors can make the problem come and go between our wet summers and dry winters.
- Don't slam the door harder or file the latch tongue. Both make the real fault worse.
Latch, deadbolt and strike plate: the three parts involved
Most doors have two separate things that hold them shut, and it helps to know which one is giving trouble.
- The latch is the sprung, angled tongue that clicks into the frame when you push the door closed. The handle pulls it back. On a nightlatch, it's the bevelled bolt that snaps shut when the door closes.
- The deadbolt is the square-ended bolt thrown by the key or thumbturn. It doesn't spring; it only moves when you lock.
- The strike plate (also called the keep) is the metal plate on the frame with openings for the latch and bolt. Behind it is a pocket cut into the frame.
This article is about the latch: the door that won't stay closed until you lock it. If the latch works but the key won't turn or the bolt won't go across, the same alignment problems often apply, but the symptoms differ. A multipoint door is different again, and has its own guide on locks that won't engage.
What the symptom is telling you
| What you notice | Usual cause |
|---|---|
| Door bounces back open when pushed shut | Latch hitting the edge of the strike plate instead of entering the opening |
| Door only latches if you lift the handle side or lean on it | Door has dropped or moved; latch now sits above or below the opening |
| Latch clicks in, but the door rattles once closed | Gap between latch and strike too big: strike set too far out, or the door has shrunk |
| Latch tongue doesn't spring out fully, or stays in | Sticky or broken latch mechanism, dirt, or a handle spring that's failed |
| Handle stays drooping after you let go | Broken return spring in the handle or latch |
| Fine in winter, sticks or won't close in summer | Timber door swelling with humidity, or rubbing on the frame |
| Door won't close the last centimetre | Thick weatherstrip, paint build-up, hinge-side binding or a swollen door |
Why doors and latches drift out of line
A door is a heavy panel hanging off one side, so gravity is constantly working on it. Over time, a few things move:
- Hinges loosen or wear. Schlage's guidance on doors that won't latch names worn or loose hinges as a cause of a sagging door. The top hinge carries the most load, and once its screws loosen, the latch side of the door drops.
- The building settles. Older houses and frames can shift and warp, and a frame that's slightly out of square changes where the latch meets the strike.
- Timber moves with the weather. Changes in temperature and moisture can warp a door. Johannesburg gets most of its rain in summer, often as afternoon thunderstorms, while winters are dry, so a timber door that closes easily in July may stick or swell after a run of summer storms.
- Weatherstrip and paint. A new, thick draught seal or several layers of paint can push the door back far enough that the latch can't reach.
- The hardware wears. Springs tire, latch tongues get chewed by years of hitting a misaligned strike, and fixing screws work loose.
ASSA ABLOY's product care guidance makes the connection between the two: faulty hinges, warped doors and distorted frames put extra load on the lock and shorten its life. A latch that's been fighting a dropped door for months often needs attention even after the door is sorted out.
Simple, safe checks
None of these involves taking the lock apart.
- Look at the gaps. With the door closed, look at the gap between the door and the frame along the top and the latch side. An even gap is a good sign. A gap that's wide at the top on the latch side and tight at the bottom suggests the door has dropped.
- Find where the latch touches. Rub a little chalk or lipstick on the latch tongue, close the door gently and open it again. Schlage suggests this test: the mark shows exactly where the latch hits the strike plate.
- Read the mark. A mark below the opening means the door has dropped. A mark to one side means the strike or door has moved sideways. A mark in the opening means alignment is fine and the problem is elsewhere.
- Check the hinge screws. Open the door and see whether the top hinge moves when you lift the latch edge slightly. Loose screws are worth tightening with the right screwdriver. If they just spin, the holes are stripped and need proper repair.
- Test the latch with the door open. Turn the handle and let go. The latch should snap out fully and the handle should spring back. If it doesn't, the problem is the lock, not the alignment.
- Check the strike pocket. With a torch, look behind the strike plate opening. Paint, a lump of filler or a pocket that's too shallow can stop the latch from going in fully.
What not to do
- Don't slam it harder. It may click shut today, but every slam batters the latch tongue, loosens the strike and jars the hinges further.
- Don't file the latch tongue down to make it fit. You'll weaken it and it may no longer reach far enough into the frame to hold the door securely.
- Don't remove the strike plate and leave the latch catching on bare timber. The frame splits and the door becomes much easier to push open.
- Don't spray any old lubricant into the latch. ASSA ABLOY's care guidance warns against silicone-based lubricants, which turn tacky, and against using too much of any lubricant, which holds dust. Use what the lock maker recommends.
- Don't prop or wedge a self-closing or fire door because it won't latch. Get the latch fixed instead.
Locksmith, carpenter or both?
Some latch problems belong to a locksmith, some to a carpenter, and some need a bit of both.
| Problem | Who |
|---|---|
| Strike plate needs moving, adjusting or replacing | Locksmith |
| Latch, handle spring or whole lock worn or broken | Locksmith |
| Loose hinge with stripped screw holes | Locksmith or carpenter, depending on the extent |
| Swollen, warped or split door, or a frame that's moved badly | Carpenter first, then the lock can be adjusted |
| Steel or aluminium door with worn hinges or frame damage | Door supplier or fabricator, with the lock adjusted afterwards |
Our lock repair service covers adjusting or replacing strikes and latches and sorting out loose hinge fixings where the door itself is sound. If the lock is past repair, we'll quote for a replacement on the spot. If the door needs a carpenter, the technician will tell you so rather than adjusting a lock to fit a door that's still moving.
Details and photos that help
Send these on WhatsApp before we come out and the technician will arrive with a better idea of what's needed:
- a photo of the whole door, closed, showing the gaps around it
- a close-up of the strike plate on the frame and the latch on the door edge
- a photo of the chalk or lipstick mark, if you tried that test
- whether it's timber, steel or aluminium, and an outside or inside door
- whether it happened suddenly (after a slam, a storm or a break-in attempt) or gradually
The R250 call-out applies, you get a quote on site before any work starts, and you pay by EFT, cash or card. If a forced entry caused the problem, see our break-in repair service too.
Questions
Why does my door latch fine in winter but not in summer?
Timber absorbs moisture in humid weather and swells, then shrinks again when it dries out. A door that's only just aligned can stop latching in one season. Adjusting the strike can help, but a door that changes a lot may need a carpenter's attention.
Is it safe to leave a door that won't latch but still locks with the key?
If the deadbolt still goes fully into the frame, the door is secure while locked. But a door that won't latch tends to be left unlocked by accident, and the misalignment usually gets worse, so it's worth sorting out soon.
Can I just move the strike plate myself?
On a simple interior door, a confident DIYer often can. On an outside door, moving the strike means new screw holes and a new pocket in the frame, and a poor job weakens the very part that resists a kick. That's where a locksmith earns their call-out.
Need a locksmith to look at it?
If this hasn't solved the problem, our lock repairs service covers it. We're a mobile locksmith in Johannesburg, so we come to your door. Areas where this comes up often include Parkview, Westcliff, Houghton, Melville.
Sources and further reading
- Schlage: Door won't latch — Causes including loose or worn hinges, settling, temperature and moisture warping, thick weatherstrip, shallow bolt pocket; chalk or lipstick test.
- ASSA ABLOY South Africa: Product Care and Maintenance (PDF) — Faulty hinges, warped doors and distorted frames overload lock components; avoid silicone-based lubricants and excessive lubricant.
- Wikipedia: Johannesburg (climate) — Rainfall concentrated in summer with frequent afternoon thunderstorms; dry, sunny winters; humidity highest in summer.