Quick answer
A composite door that's difficult to open is usually a swollen weatherseal, a stiff cylinder or gearbox, or a hook caught behind its keep rather than retracting fully. Coastal humidity in Cornwall makes seal swelling especially common. Diagnosis takes minutes; most fixes are £75–£180 depending on the cause.
Overview
A door that's suddenly hard to open often points to swelling, hardware failure or a hook catching. Diagnosis is quick.
Symptoms
- Door needs a heavy pull.
- Key hard to turn on unlock.
- Handle sticky.
Common causes
- Weather seal has swollen (very common in humid coastal air).
- Cylinder or gearbox stiff.
- Hook caught on its keep.
Opening resistance tells a different story to closing resistance
It's worth separating 'hard to open' from 'hard to close', because they usually point in different directions. A door that's hard to close but opens fine typically has a misalignment or dropped hinge issue. A door that's hard to open specifically — needing a firm pull even after the key has turned and the handle been lifted — more often points to a seal that's swollen and gripping the frame, or a mechanism that isn't fully retracting.
The distinction matters for diagnosis speed: if you can tell us on the phone which direction the resistance is in, we arrive with the right parts on the van rather than guessing.
Seal swelling: the Cornwall-specific culprit
Weatherseals are made from EPDM rubber or similar compounds designed to compress and rebound thousands of times. In consistently humid coastal air — which much of Cornwall experiences for large parts of the year — seals can absorb a small amount of moisture and swell slightly, enough to create real resistance when a door has been locked overnight and needs to be pulled free the next morning.
This is more pronounced in older seals nearing the end of their service life (typically 8–15 years), and in properties directly exposed to sea air where the seal material degrades faster. If the door only feels stiff to open first thing in the morning or after a spell of wet weather, seal swelling is the most likely explanation.
Mechanical causes: cylinder, gearbox and hooks
If the key turns with noticeable resistance, the cylinder itself may be dry or contaminated with old lubricant and dust — a common issue in exposed doorways where wind blows grit into the keyway over years. This is a straightforward fix with the correct lock lubricant and, if needed, a cylinder replacement.
If the key turns smoothly but the door still won't pull open, check whether a multi-point hook has caught behind its keep plate rather than retracting cleanly — a symptom of the same alignment issues that cause catching on closing. This needs the same calibrated hinge or keep adjustment, not force.
- Key stiff to turn: cylinder needs cleaning, lubricating, or replacing.
- Key turns fine, door still stuck: hook caught on keep, needs alignment.
- Only stiff in damp weather or mornings: seal swelling, needs seal assessment.
Why forcing a stiff door makes things worse
A door that's stiff to open is often pulled harder and harder by frustrated occupants, and that repeated extra force accelerates wear on exactly the components already under strain — the cylinder cam, the gearbox internals, and the hinge fixings. What starts as a minor seal-swelling annoyance can, over a season of being yanked open daily, turn into genuine hardware damage.
It's also a habit that's particularly risky with young children or elderly residents pulling hard on a door that then suddenly gives way.
Holiday lets and difficult-to-open doors: a specific risk
For holiday let owners, a door that's occasionally difficult to open is a guest-experience and safety issue as much as a mechanical one — a guest struggling with a stiff front door on changeover day, in the rain, with luggage, is a bad first impression and a genuine trip-hazard risk if they end up yanking it while off balance.
We recommend seasonal servicing ahead of the main letting season for exactly this reason: a seal or lubrication check in spring catches swelling issues before the summer booking calendar starts, rather than during it.
A typical example from a Falmouth apartment
A ground-floor flat in Falmouth, close enough to the water to get regular salt-laden air, reported the front door being 'nearly impossible' to open most mornings but fine by midday. This pattern — worse in damp morning air, easing as the day warmed and dried — is a textbook seal-swelling signature. Replacing the compression seal section on the latch side resolved it completely, and no hinge or lock work was needed at all.
Hinge types and how much 'stiffness' is adjustable
Stiffness on opening is often assumed to be a lock problem, but the majority of cases we see trace back to hinge compression being set too tight, pulling the door hard against its seals so that breaking that seal on opening takes real effort. Standard flag hinges have a compression cam with roughly 2 to 3mm of adjustment, and backing this off slightly is often enough to restore an easy, single-hand opening action without compromising the seal against wind and rain.
Where the door has concealed frame-mounted hinges, compression is usually set once at installation and rarely needs revisiting unless the seal itself has changed thickness — for example after a seal replacement using a slightly different profile than the original, which can leave the door noticeably stiffer even though nothing about the hinges has changed.
Frame settlement in older Cornish openings and its effect on opening effort
In granite and cob properties where the frame was packed to true up an irregular opening, settlement over years can push the frame very slightly inward at one point, effectively narrowing the gap the door has to swing through. The door isn't dropped and the hinges haven't failed — the frame itself has moved a fraction, and the symptom is a door that takes noticeably more effort to open than it used to, particularly at one specific point in its swing rather than throughout.
This is diagnosed by checking the reveal gap at multiple heights rather than just one — an even gap top to bottom rules out frame movement, while a gap that narrows toward one end points to it, and no amount of hinge adjustment on the door itself will resolve a frame that has genuinely shifted.
Seasonal timing: why stiffness peaks in humid weeks
A door that's difficult to open shows a clear seasonal signature when the cause is expansion rather than hinges: it gets worse through warm, humid spells — often July through September in Cornwall, and again during damp, mild winter weeks when humidity is high even though temperatures are low — and eases off during cold, dry snaps. If you notice the effort needed to open your door tracking the weather rather than staying constant, that's a strong pointer toward seal or slab expansion rather than a hardware fault.
Booking an assessment during one of these humid peaks, rather than waiting for a dry spell when the door may temporarily behave normally, gives us the best chance of seeing and measuring the problem at its worst, which makes for a more accurate and lasting adjustment.
When a stiff door has gone beyond what adjustment can fix
If a door remains difficult to open even at full compression adjustment loosened to its minimum, and the frame is confirmed square, the remaining causes are usually a swollen door slab that's simply too large for its frame, or a compression seal that's reached the end of its service life and lost its designed give. Both of these sit beyond hinge adjustment: a persistently oversized slab may need light easing at the factory-finished edge by a specialist, and a perished seal needs replacing outright rather than compensated for by loosening hinges further, which only reintroduces draughts and rattling.
Typical repair costs in Cornwall
| Work | Typical price | Notes |
|---|---|---|
| Cylinder clean, lubricate and test | £75–£95 | First step where the key itself feels stiff |
| Weatherseal section replacement | £80–£140 | Common coastal-humidity fix |
| Hook/keep realignment | £90–£150 | Where a hook is catching rather than retracting |
| Cylinder replacement (worn beyond cleaning) | £95–£160 | Includes upgraded anti-snap cylinder option |
Guide prices only — we confirm the cost after seeing the door.
When to call a professional
- Nothing you do fixes it.
Prevention
- Silicone-treat seals twice a year.
