uPVC Door Won't Lock | What's Actually Going Wrong and What It Costs to Fix

Few things make a uPVC door owner ring a locksmith faster than this. You push the door shut, lift the handle to throw the locking points, and it sticks. You push harder. Still sticks. Two minutes of wrestling later it's locked, you're not sure how, and you really don't want to do that again at 7am tomorrow.

That's the classic sign of a multipoint gearbox on its way out. It's also one of the most over-replaced doors in the country, because people get told they need a new one when they don't.

What's actually happening

A uPVC door doesn't have a single lock. It has a gearbox in the centre of the door driving hooks, rollers or shoots that fire into the frame at three to five points up the edge. The euro cylinder you turn with the key engages the gearbox, but the gearbox does the work.

When it wears, three things tend to happen, usually in this order:

1. The handle gets stiff to lift. The mechanism is dragging and you're forcing it.
2. You start needing two or three lifts to get it to engage.
3. Eventually it locks but won't unlock, or unlocks but won't lock.

That last one is when most people ring in a hurry, because either the door's open and won't secure, or it's shut and won't let them out.

Why "you need a new door" is usually wrong

A lot of uPVC firms in Basingstoke quote a new door for this, not because the door is broken, but because that's what they sell. The slab itself is rarely the issue. Even at fifteen years old, a uPVC door is mostly fine. It's the moving parts inside that wear: the gearbox, the rollers, the hinges.

A new gearbox costs us between £40 and £140 wholesale depending on brand. Fitted on the van, you're usually looking at £180-£260 all in. A new door is £900-£2,000. Plenty of people come close to spending the two grand because nobody told them the £200 option existed.

What I actually do at the door

It tends to go like this:

• Confirm the symptom. Stiff to lift, stiff to turn, or both?
• Open the door with the handle up and look at the edge. Does the gearbox engage cleanly? Does it move at all?
• Check alignment. Half the time the door's just dropped on its hinges, and half an hour of adjustment fixes it with no parts cost.
• If the gearbox is genuinely gone, identify the brand. GU, Yale, Fuhr, Lockmaster, Maco, Roto, Mila, ERA, Avocet, Winkhaus, the common ones I carry.
• Replace the gearbox, refit or upgrade the cylinder, realign the door and adjust the keeps so it locks like new.

The whole job, alignment included, is usually 45 minutes to an hour.

Catch it before it locks you out

You don't have to wait for the door to trap you. Watch for these:

• The handle is stiff on the first lift in the morning, easier later.
• You have to slam the door before it'll lift, the alignment's drifting.
• The door rattles in the frame when shut, the keeps are loose.
• A grinding noise when you lift the handle.
• One locking point, top or bottom, doesn't seem to fire.

Any of those on a door more than five or six years old is a gearbox warning. Sorting it then is a booked visit. Ignoring it is a lockout call-out.

When it really is a new door

Three cases where I'll be honest and say the door's past saving:

• The slab has delaminated, the layers coming apart, common on early-2000s composite doors that have been south-facing for fifteen years.
• The frame is split or rotting, almost always the wood-trimmed uPVC, not the all-PVC frames.
• The locking points have torn through the door edge from years of forced lifting.

In all three I'll tell you what I see and point you to a door fitter. I don't fit doors. I fix locks.

When to ring

If the handle's sticking, you're mid-lift, or you're already locked out, ring the office. The earlier we catch a failing gearbox the cheaper it is, and we cover RG21 to RG29 with the common mechanisms on the van, quote on the call, fixed before we start.