Quick answer
Threshold adjustment usually means correcting how the door meets its seal - either by adjusting the hinges so the door sits square again, or by resetting or shimming the threshold bar itself. It's a common fix for doors that have dropped slightly over time and typically costs £65-£190 rather than needing a full replacement.
Overview
Certain thresholds (adjustable Part M-compliant types) have a blade that can be raised or lowered to improve sealing. A screwdriver and 10 minutes.
Symptoms
- Draught or light under the door.
- Threshold blade sits too low or too high.
Common causes
- Blade needs setting.
Why doors need adjusting at all
Composite doors are heavy, and over years of daily use the hinges take on a small amount of wear, letting the door drop a millimetre or two at the handle side. That's often enough to break contact with the threshold seal along part of its length, even though the seal itself is perfectly serviceable.
Timber and masonry around the frame also move slightly with seasonal wet and dry cycles, particularly noticeable in older Cornish properties with cob or granite construction, which can throw a previously well-set door slightly out of true against its threshold.
It's also worth checking the multi-point mechanism's keeps for wear at the same time as any hinge adjustment, since a door that's been dragging slightly on a dropped hinge often also shows uneven wear on its keeps, and addressing one without the other can leave a job half done.
Hinge-side adjustment versus threshold-side adjustment
Most modern composite doors have adjustable hinges - usually with small grub screws or cam adjusters allowing the door to be nudged up, down, sideways or in compression against the frame. Correcting a dropped door at the hinge is often the quicker and less invasive fix, and it addresses the root cause rather than the symptom.
Threshold-side adjustment is needed when the bar itself has moved, is sitting slightly proud or low against the sub-frame, or when the building beneath it has settled. This involves lifting the threshold, checking the packing underneath, and resetting it level before refitting.
On uPVC-framed composite doors the frame itself can flex very slightly with temperature, meaning a door that locks perfectly on a cold morning can feel tight by a warm afternoon; this is normal within limits and doesn't necessarily mean an adjustment is overdue, but a persistent, worsening tightness across seasons usually does.
- Hinge adjustment: corrects a dropped or misaligned door leaf
- Threshold shimming: corrects a bar sitting unevenly on its sub-frame
- Combined adjustment: needed when both have drifted over time
Signs your door needs adjusting
A door that's harder to lock than it used to be, that needs lifting or slamming to engage the multi-point mechanism, or that lets a visible sliver of daylight show at one corner of the threshold when closed, is telling you it's out of alignment. These symptoms develop gradually, so many homeowners adapt to them without realising how far the door has drifted from its original set.
A door that needs increasing effort to lock over a period of weeks or months, rather than staying consistent, is a reasonably reliable sign that something is wearing rather than just settling, and is worth having looked at before the mechanism is forced repeatedly, which can accelerate wear on the hooks and keeps.
Doing it yourself versus calling someone out
Minor hinge adjustments on some doors can be made with an Allen key by the homeowner, but getting it wrong risks over-tightening a hinge cam and creating a new problem, or masking a more serious issue like a failing gearbox that just happens to feel similar. Because a wrongly adjusted door can also compromise the multi-point locking engagement and therefore security, we'd recommend having any adjustment beyond the most obvious done by someone who fits these doors regularly.
We'd also flag that some adjustable hinge systems have a limited range of travel - once a hinge has been wound to its maximum adjustment, any further drop in the door means the hinge itself needs replacing rather than further adjusting, and continuing to force adjustment beyond that point can strip the cam mechanism.
The link to weathertightness and BS 6375
BS 6375 sets out performance classifications for weathertightness in doorsets, covering resistance to air permeability, water tightness and wind load. A doorset tested and rated to a given class assumes it's installed and maintained in the condition it was tested in - a door that's dropped out of alignment and lost even contact with its seal is no longer performing to the standard it was originally rated for, regardless of what the door itself is capable of.
This is one reason threshold and hinge adjustment isn't purely a cosmetic or convenience job; it directly affects how well the door keeps weather out.
For households in older Cornish properties where the surrounding masonry itself moves seasonally, it can be worth checking door alignment at the same time each year, ideally after the wettest part of winter has passed, so any adjustment accounts for how the building has settled after damp weather rather than during it.
What we check during an adjustment visit
A proper adjustment visit checks the door's alignment in the frame at multiple points, tests each hook and bolt of the multi-point mechanism for full engagement, inspects hinge condition for wear rather than just misalignment, and only then makes adjustments - because a hinge adjustment on a worn hinge is a temporary fix that will need repeating.
Keeping a simple record of what adjustment was made and when also helps if the same issue recurs, since a fitter returning to a door with that history can quickly tell whether a hinge is progressively wearing out or whether something else, like a frame fixing, has failed.
When adjustment isn't enough
If a door has dropped because a hinge has genuinely worn out, or because the frame itself has distorted, adjustment alone buys time rather than solving the problem permanently. In those cases hinge replacement or, occasionally, frame packing correction is the more lasting fix, and it's worth being told this rather than having the same adjustment repeated every few months.
It's also sensible to have adjustment carried out as part of a wider annual check on the door rather than as an isolated job, since a fitter looking at hinge alignment can often spot early signs of gearbox wear or a threshold problem developing at the same time, catching a bigger repair before it becomes necessary.
Homeowners occasionally ask whether adjusting a door themselves with a widely available online guide is worth attempting - the risk is less about the adjustment itself and more about not recognising when the door's behaviour actually indicates a different, unrelated fault that adjustment alone won't fix.
Typical repair costs in Cornwall
| Work | Typical price | Notes |
|---|---|---|
| Hinge adjustment (per door) | £65-£95 | Quick fix for a dropped door |
| Threshold reset & shimming | £110-£190 | Where the bar itself has moved |
| Hinge replacement (worn beyond adjustment) | £90-£150 | Per hinge, includes fitting |
| Combined hinge & threshold service | £150-£260 | Covers both in one visit |
Guide prices only — we confirm the cost after seeing the door.
When to call a professional
- Non-adjustable threshold - different fix.
Prevention
- Include in annual service.
