Before assuming the latch or lock has failed, check whether the latch is simply missing the strike plate opening. Doors settle and houses shift slightly over the years, and a door that used to close perfectly can drift out of alignment with its strike plate by just a few millimetres — enough to stop the latch catching even though nothing has actually broken.
Check the alignment first
Close the door slowly and watch exactly where the latch meets the frame. If it is hitting the strike plate above, below, or to one side of the opening rather than sliding cleanly into it, you have found the cause — and this is almost always fixable in minutes, not a sign the lock itself needs replacing.
Common causes
| Cause | How likely | Typical sign |
|---|---|---|
| Strike plate misaligned with the latch | Very common | Latch visibly hits the plate rather than sliding in |
| House settling shifting the frame slightly | Common | Gradual change over months or years, older homes especially |
| Loose hinges allowing the door to sag | Common | Door drags on the floor or catches at the top on one side |
| Humidity causing the door to swell | Common | Worse in humid weather, improves when dry |
| Strike plate or latch mechanism damaged | Occasional | Visible damage, or latch does not extend/retract properly |
| Door frame warped | Occasional | Older or exterior doors exposed to weather |
How to fix it
- Identify exactly where the latch is missing the plate
Close the door gently and look at the gap between the latch and the strike plate opening. Note whether it is too high, too low, or too far to one side.
- Try enlarging the strike plate opening slightly
For a small misalignment, a metal file can widen the opening in the strike plate itself just enough to let the latch catch. This is a minor adjustment, not a structural change, and works well for gaps of just a millimetre or two.
- Reposition the strike plate
For a larger misalignment, remove the strike plate’s screws, reposition it to align with the latch, and if needed, fill the old screw holes with a wood filler or golf tee before redrilling in the new position.
- Check and tighten hinge screws
Loose hinges let the whole door sag slightly, which throws off alignment at the latch even if the strike plate itself has not moved. Tighten all hinge screws, and replace any that spin freely in a worn-out hole with a longer screw.
- Consider the shim trick for a sagging door
A cardboard or wood shim placed behind the top hinge, between the hinge and the frame, tilts the door slightly and can correct a sag that has thrown off the latch alignment — a well-known, effective fix that avoids replacing or repositioning hardware.
When the problem is the hinge side
If the door drags on the floor, catches at the top corner, or visibly hangs at an angle, the fault is more likely a sagging hinge side than the latch or strike plate specifically. Address the hinges first in this case — realigning the strike plate on a door that is still sagging just moves the same underlying problem rather than fixing it.
If a door only sticks or fails to latch during humid months and closes fine the rest of the year, the wood is swelling with moisture rather than anything being structurally wrong. This does not always need a permanent fix — light sanding on the latch edge helps, but can leave a gap in drier months if overdone.
When to call someone in
Call a carpenter or handyman if the door frame itself appears warped or damaged, if repositioning the strike plate and adjusting hinges does not resolve it, or if this is one of several doors in the house all showing similar symptoms at once — which can indicate a foundation or structural settling issue worth a broader assessment rather than door-by-door fixes.
