A uPVC or composite door that has to be lifted, shouldered or leaned on to lock is not broken — it has almost always just moved. Doors expand and contract with temperature, hinges wear, and heavy composite slabs settle over the first year or two.
Nearly all of it is adjustable with an Allen key. This guide explains what each adjustment does and the order to do them in, plus when to stop and call someone.
How to adjust a uPVC or composite door: step by step
- 1
Identify the hinge type
Look at the hinges. Flag hinges (a barrel with caps top and bottom) are the most common on uPVC. Butt hinges and rebate hinges appear on composite doors and adjust differently.
- 2
Diagnose the movement needed
Close the door slowly and watch where it catches. Rubbing at the top of the latch side means the door has dropped; rubbing along the whole latch edge means it needs to move sideways; a handle that will not lift means the hooks are not meeting the keeps.
- 3
Remove the hinge caps
Prise off the plastic caps to expose the adjustment screws. Most take a 4mm or 5mm Allen key.
- 4
Adjust height first
The screw in the top or bottom of the hinge barrel raises and lowers the whole door. Adjust all hinges by the same amount, a quarter turn at a time.
- 5
Adjust lateral position
The screw on the face of the hinge moves the door towards or away from the hinge jamb. Adjust the middle hinge last, as it controls the bow of the slab.
- 6
Adjust compression
The third adjustment pulls the door tighter onto or away from the weather seal. Aim for a door that closes with firm pressure but does not need slamming.
- 7
Fine-tune the keeps
If the hooks still catch, loosen the keep plate screws on the frame and shift the keep a millimetre, then retighten and test.
- 8
Test and lubricate
Open and close ten times, lock and unlock with the key, then apply a light machine oil to the hooks and rollers and a silicone spray to the gaskets.
What each symptom usually means
| Symptom | Likely cause | Fix | Typical cost if done by a trade |
|---|---|---|---|
| Handle will not lift to lock | Door dropped, hooks missing keeps | Height adjustment | £45 – £80 |
| Catches on the frame at the top | Hinge wear or slab settling | Height and lateral adjustment | £45 – £80 |
| Draught along the latch edge | Compression too loose | Compression adjustment | £45 – £80 |
| Key turns but door not locked | Gearbox failing | New multi-point mechanism | £140 – £280 |
| Handle floppy or spinning | Broken spindle or handle spring | New handle set | £60 – £120 |
| Door binds only in hot weather | Thermal expansion, over-tight compression | Ease compression slightly | £45 – £80 |
| Lock stiff in cold weather | Dry cylinder | Lubricate with graphite or PTFE | £0 – £45 |
Tools you need
- Allen keys, 3mm to 6mm
- Pozidriv screwdrivers
- A small spirit level
- Light machine oil for the mechanism and silicone spray for the gaskets
- A torch — the keeps are usually in shadow
Ground rules that prevent damage
Work in small increments. A quarter turn moves more than you expect, and it is far easier to creep up on the right position than to undo an over-correction.
Never force the handle when the hooks are catching. Multi-point gearboxes are the most common failure on uPVC doors and forcing a misaligned door is exactly how they break. If the handle will not lift with light pressure, adjust the door, not your grip.
Lubrication schedule
Once a year, apply light machine oil to every moving part of the multi-point strip — hooks, rollers and the latch — and work the handle to distribute it. Use a graphite or PTFE-based lubricant in the cylinder, never oil, which attracts dirt and gums the pins.
Wipe the gaskets and give them a silicone spray at the same time. Five minutes a year noticeably extends the life of the hardware.
When to call someone out
A mechanism swap is generally a one-hour job for someone who does it regularly, and it is far cheaper than a new door. We carry common gearboxes and cylinders on the van across Central Scotland.
- The gearbox has failed and the handle spins without engaging.
- The slab itself is bowed rather than the hinges being out.
- The frame has moved because of a settling lintel or a failed sub-frame.
- A composite door has dropped repeatedly despite adjustment, which usually means undersized hinges.
- The door is your only secure entrance and you are not confident leaving it half-adjusted.
Common questions
uPVC expands in heat. If the door was adjusted very tight in winter it will bind in July. Ease the compression a fraction.
Want a straight answer on your own windows or doors?
DM Installations fits and repairs windows and doors across Central Scotland — Cumbernauld, Glasgow, Falkirk, Stirling and the surrounding towns. Free survey, written quote, and an honest answer on whether you need a repair or a replacement.
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