A door that is getting stiff to close or harder to lock is trying to tell you something. Almost every "my door won't lock at all" emergency our locksmiths attend started weeks earlier as a door that was simply a bit harder to pull to. Caught early, it is usually a five-minute adjustment; left until the handle finally won't lift, it can become a snapped mechanism and a locked-out family. This guide is about catching it early.
The hooks, rollers and bolts in a modern door mechanism are meant to glide into their keeps. When the door drifts out of position, or the mechanism starts to wear, those parts begin to catch — and you feel it as stiffness in the handle or the key. Stiffness is friction, and friction is strain. The single most expensive mistake is to answer that stiffness with force, because the gearbox at the heart of a uPVC or composite door is exactly the part that shears when forced. If your door has already reached the point where it won't lock at all, our separate guide on why a uPVC door won't lock walks through that stage.
Before you do anything else, open the door fully and operate the lock with the door standing open. If it works smoothly open but stiffens or fails when the door is shut, the mechanism is fine and the door is simply out of alignment — an adjustment job. If it is stiff even with the door open, the problem is inside the mechanism itself. That one test tells you which of the causes below applies.
uPVC moves with temperature. It expands in summer heat, which makes a door stiff and sticky, and contracts in hard frost, which can leave it rattly or just slightly off. If your door only misbehaves in a heatwave or only on cold mornings, that is the likely culprit. A useful temporary trick is to wipe the edges of the door with a cloth wrung out in cool water during hot spells, or warm water in cold ones, and give it ten minutes — it nudges the material back toward its normal size. It is a stopgap, not a cure, but it can buy you a day until a locksmith visits.
Stand back and look at the gap running around the closed door. If it is noticeably wider at the top than the bottom, or tapering down one side, the door has "dropped" on its hinges — the most common reason a once-smooth door starts catching. Most modern uPVC hinges adjust in two or three directions, and a confident DIYer can sometimes improve things by adjusting the hinge screws. The keeps and any glazing-packing work that squares the door in its frame are better left to someone who does it daily, because it is easy to over-adjust and chase the problem around.
Before you assume the worst, rule out the simple stuff that our locksmiths fix in minutes:
The classic oil-based maintenance spray is the wrong tool here: it attracts dust and grime that gum the mechanism up over time, so the door feels better for a fortnight and worse forever after. Use a dry PTFE, silicone or graphite lubricant on the moving parts, locking points and the cylinder once or twice a year, and a healthy door will stay healthy.
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The moment the handle won't lift or the key won't throw the bolts, a sticking door has become an unlocked home — and that is urgent, not a job for next week. The good news is that none of this means a new door: a realignment is a quick visit, and even a worn gearbox is a replaceable unit a locksmith can usually match and swap the same day, keeping your handles and often your cylinder. Our price guide sets out fair ranges, and you can read more about the repair itself on our uPVC lock and door repairs page. If your door has stopped locking tonight, treat it as an emergency and find your local LocksmithLocal to put it right today.
Forcing a jammed key is how it snaps. The calm, in-order fix: resetting the key position, the right dry lubricant, frozen locks, and the line where it becomes a locksmith's job.
Two different problems wear the same words. How to tell a door-and-mechanism fault (a garage-door engineer's job) from a lock fault (ours) — and why the springs are the one thing never to touch.
A spinning handle and a stuck latch are usually a small, cheap part — until they're forced. The finger test that finds the fault, the likely culprits, and how to avoid a door-off job.