A door that still closes is not necessarily a door that still works. Most of the failure modes below develop slowly, and by the time a door is obviously broken the damage has usually been visible for a season or more. Here are seven things worth checking, and what each one actually tells you.
1. The daylight test
Do this at night with the room light on. Stand outside the closed door and look along the edges: the top, both sides, and the bottom. Any light coming through is air coming through.
Small gaps at the bottom are normal and deliberate — a door needs clearance to swing without binding on an uneven floor. A gap that has appeared along the top or the hinge side is different: it usually means the frame has moved or the leaf has twisted, not that the door was always like that. Compare both sides of the hinge line. If one side of the leaf sits noticeably tighter against the frame than the other, the door is no longer square in its opening.
2. The door fights you when you close it
A door that needs a shoulder to close, or that you have to lift to get the latch to catch, is telling you something has changed shape. It is rarely the lock.
- Scuff marks on one edge only point to the leaf having moved rather than the frame.
- Latch misses the strike plate by a few millimetres usually means the leaf has dropped, which is a hinge problem.
- Latch misses by a lot, or the gap is uneven usually means the panel has moved or the frame is out of square.
- Hinge screws that keep coming loose usually means the screw holes are stripped or the timber behind them has softened — often from moisture.
A useful test: if sanding or planing the edge fixes it, the leaf has swelled. If the problem comes back within a season, the frame is the real issue and planing will only buy you a few months.
3. Security hardware that has started to move
Check three things. A lock cylinder that turns or wiggles in its housing. A deadbolt that does not extend fully when you throw it. Visible corrosion or pitting on hinges, screws or the lock body.
These matter because a door’s security comes from the whole assembly, not the lock alone. A deadbolt that only half-engages is not doing the job you paid for, and a corroded hinge is a hinge that will eventually fail under load. If the door leaf itself is still sound, this is normally a repair rather than a replacement — but it is not something to leave.
4. Energy bills and comfort
A leaking door is easiest to notice by its effects rather than by looking at it. Rooms that are noticeably cold or hot compared to the rest of the house. Draughts at ankle level near the door. A heating or cooling system that seems to run more than it used to.
The cause is usually the perimeter seal rather than the panel. Weatherstripping and door sweeps are inexpensive and replaceable, and worn seals are the most common reason a sound door performs badly. Check the seal before you assume the door needs replacing.
5. Cosmetic damage versus structural damage
It helps to separate the two, because they call for very different responses.
Cosmetic — can wait: faded or chalking paint, minor surface dents, scuffs, a handle that needs tightening.
Structural — address now: cracks running from the hinge or lock mortise into the panel; soft, crumbly or discoloured timber at the bottom rail; a veneer or skin that has lifted or bubbled away from the core; visible swelling at the bottom edge of the leaf.
Soft timber at the bottom of a door is the one to take seriously. It almost always means water has been reaching the core for some time, and once the core is wet the problem continues even in dry weather.
6. A five-minute check you can do with a coin and a piece of paper
- Coin test on the bottom edge. Press a coin into the bottom rail and the bottom of the frame. If it sinks in easily or the material crumbles, moisture damage is already present.
- Paper test on the seals. Close the door on a sheet of paper at several points around the perimeter. If the paper pulls out with no resistance, that section of the seal is no longer doing anything.
- Level check. Rest a spirit level against the face of the door, vertically and horizontally. A leaf that is out of level in both directions has twisted, not merely settled.
7. When repair stops making economic sense
There is no universal break-even number, because it depends on what is wrong and on what a replacement costs in your market. A more useful way to think about it is by cause:
- Seals, hardware, minor adjustment — repair. These are consumable parts and are meant to be replaced on a sound door.
- A single failed element on an otherwise solid door — repair. One swollen bottom rail on a door that is otherwise flat can be addressed without replacing the leaf.
- A twisted or delaminated leaf, or a core that has taken on water — replace. Once the panel structure has moved, no amount of adjustment holds it straight.
- Repeated repairs to the same door over successive seasons — replace. That pattern means the underlying cause has not been fixed.
What actually prevents this
Almost every failure above traces back to moisture. Water reaches a door through the cut edges and the bottom rail far more often than through the face, which is why the specification of the core and the edge sealing matters more than the finish.
If you are choosing a replacement, the figures that predict how it will behave in a wet room or a humid climate are on the technical data sheet — water absorption, core density, edge treatment. Our checklist for specifying WPC doors sets out which numbers to ask for and which test standards they should be tied to. If the door you have is bowing rather than rotting, this guide to warping in humid climates covers the cause in more detail.
None of these checks require a specialist. They require ten minutes, a torch, and the willingness to go outside in the dark.
Next step: If you are specifying doors for a project in a humid climate, send us the application, the destination market and the volume, and we will send the technical data sheet for the matching product along with sample availability.
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