Why Won’t My Door Latch Properly? The Lipstick Test
A door that won’t latch is almost never a lock fault. The latch and the strike hole have stopped lining up, usually because the frame has moved, the hinges have sagged, or the door has swollen. The lipstick test finds the misalignment in about two minutes and tells you which way to move the strike.
You pull the door and it bounces back. Or it looks shut and isn’t, and you find out when the wind takes it at three in the morning.
Everyone’s first instinct is that the latch has broken. It hasn’t. It is a couple of millimetres out, and a couple of millimetres is all it takes.
The lipstick test
Genuinely the fastest diagnostic on this site, and it costs nothing.
- Put a smear of lipstick, chalk or a marker on the face of the latch bolt.
- Pull the door to as though closing it, firmly, then open it again.
- Look at the strike plate. The mark shows you exactly where the latch is hitting.
Mark above the hole means the door has dropped. Below means it has risen, which is rarer. To one side means the door has moved in or out relative to the frame, usually swelling or a shifted frame.
Now you know which direction to move things, instead of guessing.
What the mark is telling you
| Where the latch hits | What has happened | Usual fix |
|---|---|---|
| Above the hole | Hinges sagging, or frame settled | Tighten or shim hinges first |
| Below the hole | Frame lifted, less common | Move the strike |
| Outer edge | Door swollen, or frame pushed in | Adjust strike, or plane in extremes |
| Hits the plate flat, no entry | Latch not extending fully | Check the latch mechanism |
| Lines up but rattles | Strike too deep for the door | Move strike, or fit an adjustable one |
Try the hinges before you touch the strike
If the mark is high, go to the top hinge first. Open the door, take the weight, and try the screws. Nine times out of ten one or more has pulled loose in the jamb, and the door is hanging a few millimetres lower than it was.
The proper fix is longer screws that reach through the jamb into the framing behind it, not just into the trim. Three inches. Same screws that make a strike plate genuinely useful against a boot, so you may as well do both at once while the driver is in your hand.
If the hinges are solid, move the strike
Unscrew the plate, file the hole in the direction the mark told you, or move the plate itself and fill the old screw holes. Filing is quicker and looks worse. Moving is slower and looks right.
Either way, check the depth. A lot of latch rattle is not alignment at all — it is a strike sitting too far back for a door that has shrunk.
Why this is so common here
Because the ground moves. This metro sinks somewhere between 0.2 and 0.8 inches a year, and slabs do not settle evenly. One corner drops, the frame goes slightly out of square, and every door hung in it inherits the twist.
Then the humidity does the rest. Timber doors take up moisture through the summer and give it back through the winter, so a door that latches fine in January can be a millimetre proud in July. Some doors in Kenner latch for half the year and fight you for the other half.
And a lot of frames round here took a hit from Ida that never got properly put right.
The part that actually matters
We’ll say the bit that costs us money: this is usually a screwdriver and twenty minutes, and you do not need us for it.
What you should not do is keep slamming it, or start lifting the door by the handle to make it catch. That is how a latch problem becomes a snapped key — you end up using the key as a lever against a bolt that has nowhere to go, and brass loses that argument. There is more on that in why won’t my deadbolt turn.
When it is worth ringing someone
If the frame is visibly out of square, if the door is a heavy exterior one that has dropped badly, or if you have filed the strike twice already and it has moved again — the frame is the problem and that is carpentry as much as locksmithing. Worth being told that plainly rather than buying another lock.
Tell us where the lipstick mark landed and we can usually tell you what you are dealing with before anyone comes out. Ranges are on the prices page.