A door that only dragged a little in March will fight you properly by July. uPVC doesn't behave like timber: instead of swelling with damp, it expands with heat, and a south-facing door can pick up enough length on a hot afternoon to bind against the frame just when you've got both hands full of shopping. The good news is that most sticking comes down to two or three fixable causes, and you rarely need a new door to sort it.
Work out what's actually rubbing
Before you touch anything, find the contact point. Shut the door slowly and watch where it catches, or run a strip of paper around the gap and see where it grips. Most uPVC doors stick in one of three places: the bottom corner on the hinge side (the door has dropped), the top edge (heat expansion or a sagging frame), or along the latch side (the keep is out of line). Knowing which one saves you an afternoon of guessing.
The quick summer test
If the door swings fine first thing in the morning and jams by mid-afternoon, that's thermal expansion, not a fault. You can ease it with adjustment rather than force. If it sticks all day, every day, something has moved and needs realigning.
Adjusting the hinges
Almost every uPVC door has adjustable hinges, and this is where 80% of problems get solved. Look for the flag or butt hinges down the opening edge. Depending on the brand, you'll find adjustment screws hidden under a small clip-off cap.
- Lateral (side-to-side): moves the door towards or away from the latch. Use this if the door catches on the lock side.
- Vertical (height): lifts or drops the whole door. Use this if the bottom corner is scraping the sill.
- Compression: pushes the door tighter or looser against the weather seal.
Turn screws a quarter-turn at a time, then test. Adjust the hinges evenly — cranking the top one hard while ignoring the bottom just twists the slab and creates a new contact point somewhere else. A 4mm and 5mm Allen key will cover most fittings.
When the latch side is the problem
If the hinges are fine but the door won't pull shut without a shove, the strike plate (the metal keep on the frame) has usually drifted. Loosen its screws, shut the door gently so it finds its natural resting line, mark where the latch meets the keep, then nudge the plate a millimetre or two and retighten. You're aiming for the door to close under its own weight with a light push, not a hip-check.
Don't forget the simple stuff
Heat aside, a fair few "sticking" doors are just dirty or dry. Grit builds up in the bottom channel and the rollers seize. Hoover the track, wipe it with a damp cloth, and give the hinges and rollers a spray of dry PTFE lubricant — not WD-40, which attracts dust and gums up within weeks. A rubbed candle or a bar of plain soap on a sliding patio door track is an old trick that genuinely works in a pinch.
Check the weather seals too. A perished gasket that's gone hard and lumpy can hold a door proud of the frame, mimicking a swelling problem that isn't there. Replacement gasket comes on a roll for a few pounds and pushes into the channel by hand.
When to stop and call someone
If you've adjusted the hinges to the end of their travel and the door still binds, or if you can see daylight through a corner because the slab has visibly bowed, that's beyond a screwdriver. Sagging frames, failed glazing packers, or a multipoint lock that won't throw all its bolts are jobs for a window fitter. Forcing a misaligned multipoint mechanism is the fastest way to snap the gearbox inside the door — and that repair costs far more than the call-out you were trying to avoid.
Spend twenty minutes with the hinges this weekend and you'll likely head off the July jam before it starts. It's the kind of small maintenance that quietly keeps an older door going for years longer than it has any right to.