Quick answer
If your kitchen doors rub in July but ran clean in January, that is almost certainly moisture, not hardware. Melamine-faced board grows with humidity — the published figure is about 0.3% along its length between dry air and damp air, which is roughly 3mm on a two-metre pantry door and easily enough to close the gap it was built with. Adjust the hinges now and the same door will sit crooked, loose or off its overlay by February when the panel shrinks back, and you will pay someone twice. Wait until the house dries out. If the door still catches in late summer, then it is a sag or a carcass problem and worth fixing properly. The one exception: a door whose bottom edge has gone fat and stayed fat is liquid water, not season, and that never reverses.
Key points
- Melamine-faced particleboard and MDF change in length by about 0.03–0.06% for every 1% change in moisture content, which is a published panel-industry figure rather than a rule of thumb.
- NIWA's 9am readings put Henderson at 80% relative humidity in January and 92% in June and July, while Leigh on the coast barely shifts — the swing that jams doors is a west and south Auckland problem.
- Hinge travel is finite: a Blum CLIP top gives ±2mm sideways and +3/-2mm of depth, so a winter adjustment spends movement you will want back in summer.
- Seasonal swelling reverses; water swelling leaves residual thickness the panel never gives back, which makes the bottom edge the most useful thing in the kitchen to look at.
- Drying one load of washing indoors puts up to five litres of water into the house according to building.govt.nz, which is why the unheated rental with no dryer is the one that generates the callback.
The door didn't change. The air did.
A property manager rings in the second week of July. Tenant in Henderson says three kitchen doors are rubbing and the pantry won't shut without a shove. Same kitchen we handed over eighteen months back, signed off, not a single callback since. Someone will tell her to send a handyman round with a Pozidriv and wind the hinges over, and it will take him twenty minutes and the tenant will be happy. Don't do it. That kitchen was fine in January and it will be fine again in January, because nothing about the kitchen has changed. The air in the house has changed. The doors are doing precisely what the board they are made from is published to do.
This piece is about doors that bind seasonally and then free up again — where the complaint lands with the first proper southerly and quietly evaporates around Labour Weekend. It is not about a door that has dragged since the day it went on, which is an install problem. It is not about a door that has got worse every year regardless of season, which is a sag. And it is not about a door whose bottom edge has swollen and never recovered, which is water and which is a replacement. Those three get separated further down, because the diagnosis, the fix and the bill are completely different, and the most expensive mistake in this whole area is treating one as another.
What is actually moving
Your doors are almost certainly melamine-faced particleboard or MDF — melteca, in the vernacular — and that board is hygroscopic. It takes on water from the air when the air is damp and gives it back when the air is dry, and it changes size while it does. The panel industry publishes the numbers rather than leaving them to folklore. Standard and moisture-resistant MDF both change in length by about 0.03–0.06% for every 1% change in moisture content, and in thickness by about 0.3–0.5% for the same 1%. Those coefficients tie back to a stated total: a linear expansion of 0.3% and a thickness expansion of 6% across the full run from 30% to 90% relative humidity. Board used in occupied buildings normally sits at 10–12% moisture content. So the movement is small in percentage terms and completely unremarkable in engineering terms. The problem is that a door is 600mm wide and the gap around it is 3mm, and a small percentage of a big number lands squarely inside a small one.
| Door dimension | Full 30% → 90% RH (0.3%) | Half the swing (~0.15%) | Where you notice it |
|---|---|---|---|
| 400mm wide door | 1.2mm | about 0.6mm | Nowhere — the gap swallows it |
| 600mm wide door | 1.8mm | about 0.9mm | A pair closing on one 3mm gap |
| 720mm high base door | 2.2mm | about 1.1mm | Rubs the rail or the drawer below |
| 2,000mm tall pantry door | 6.0mm | about 3.0mm | Binds top and bottom, hard |
Look at where that lands. A single 400mm door under a bench has more slack than it will ever use, which is why nobody rings about those. A pair of 600mm doors meeting on one 3mm centre gap is a different story: both panels grow toward each other, so you can lose the better part of two millimetres from a gap that only ever had three. And a full-height pantry door is the one that ends up on the phone, because 0.3% of two metres is six millimetres and even half of that is enough to jam it against the rail. That is not a manufacturing fault and it is not a hinge fault. It is a 2,000mm panel behaving exactly as its data sheet says it will. If you want the background on what these doors are actually made of and why the facing matters more than people think, we have gone through what the different cabinet finishes are and how they behave separately.
Why July, and why the west and the south
Auckland is humid all year — the sea is close and there is no mountain range to dry the air out. But the year is not flat, and it is much less flat in some suburbs than others. NIWA's long-run climate record for the region gives mean 9am relative humidity by month and station, and the pattern in it is the entire explanation for your winter callbacks.
| Station | January | June | July | Annual | Jan → Jul swing |
|---|---|---|---|---|---|
| Henderson River Park (west) | 80% | 92% | 92% | 86% | 12 points |
| Auckland Airport (Mangere) | 77% | 88% | 88% | 82% | 11 points |
| Pukekohe (south) | 81% | 90% | 90% | 85% | 9 points |
| Auckland Ardmore (south) | 86% | 92% | 92% | 88% | 6 points |
| Leigh (coastal, north) | 79% | 81% | 81% | 79% | 2 points |
Henderson swings twelve points between January and July and sits at 92% through midwinter. Ardmore is the dampest place on the list all year round. Leigh, sitting out on the coast with the sea moderating everything, moves two points and effectively has no winter in humidity terms. That is why this is not a uniform Auckland problem: it is a west and south Auckland problem, and it is worst in the low-lying, shaded, poorly drained pockets that those numbers are measured in. It is also why the same kitchen spec, installed identically, generates seasonal complaints in Henderson and Papakura and silence in Devonport. When we are pricing a portfolio refresh across the west Auckland rental stock, this is a live consideration, not a footnote.
There is a wrinkle worth understanding, though, because it changes what you do about it. The outdoor air in July actually holds less water than the outdoor air in January — NIWA's vapour pressure figures for Henderson drop from around 18 hPa in summer to around 11 hPa in midwinter. Cold air simply cannot carry as much. Relative humidity climbs anyway because the air is colder, and relative humidity is what the board responds to. So your house is not damp because damp air is getting in. Your house is damp because it is cold, shut up, and you are making water inside it faster than it leaves.
The Ministry's own guidance puts hard numbers on that. Cooking puts about three litres a day into a home. Showers and baths run about 1.5 litres per person per day. Dishes, another litre. An unflued gas heater, up to a litre an hour while it is running. And drying one load of washing indoors — no vent, on a rack in the lounge because it has rained for a week — puts up to five litres into the air. Add that up in an unheated three-bedroom rental in Massey where the tenant is drying washing inside because there is no dryer and the line has been wet since May, and the kitchen doors are the least of it. The same guidance notes that 37% of surveyed houses had visible mould.
That last point catches people out constantly, because a recirculating rangehood looks like a rangehood and sounds like a rangehood. It filters grease and returns the air, water and all, to the room it came from. We have written up the ducted versus recirculating decision in full, and for anyone running tenanted stock the kitchen side of the Healthy Homes standards is worth reading before you spend anything on doors.
Why you don't wind the hinges over in July
Here is the argument the handyman will make: it takes two minutes, the tenant stops complaining, everyone moves on. Here is why it is wrong. Hinge adjustment is not free movement — it is a budget, and it is a small one. A Blum CLIP top, which is what is on most decent Auckland kitchens, gives you side adjustment of ±2mm on the front screw, which is what sets your overlay. Depth adjustment runs +3/-2mm on the rear spiral cam. Height comes off the mounting plate and depends which plate you have: ±2mm on a cam wing plate, ±3mm on a one-piece wing plate you loosen and slide. That is the whole envelope.
Now spend a millimetre of it in July. The door clears, the tenant is happy, the job is closed. Come February the panel gives that moisture back and shrinks, and you now have a door sitting a millimetre off where it was designed to sit, with a gap on one side that is visibly fatter than the gap on the other, out of line with every other door in the run. Someone rings about that. A second person winds it back. Two adjustments a year, every year, into 15mm particleboard — and hinge screws in particleboard have a finite number of bites in them before the thread is chewed and the cup starts moving under load. You have converted a free, self-correcting seasonal cycle into a permanent hardware defect and paid twice a year for the privilege. The detail work that actually keeps hardware quiet over a decade is in the setup, not in the annual fiddle.
Every July I get the same three calls. And every February I get the same three calls back — because someone adjusted them in July.
Same symptom. Three faults. Three different bills.
Telling a seasonal swell from a genuine sag
This is the part that actually earns its keep, because a sag does need fixing and no amount of waiting will fix it. The two present differently once you know what you are looking at. Seasonal swelling closes gaps evenly and symmetrically. Both doors of a pair move. The reveal narrows all the way down rather than tapering. It shows up on the tall and wide doors first because they have the most material to move. It arrives on a schedule and it leaves on a schedule, and critically, this July looks exactly like last July — it is not progressive.
A sag is geometry, not moisture. The door pivots down on its hinges, so the gap opens as a wedge — tight at the bottom outer corner, wide at the top outer corner, or the door catches the one beside it on one corner only. It affects heavy doors first, which usually means tall ones or anything with a stone or solid timber component. It gets worse year on year and it does not care what month it is. Put your hand under the outer bottom corner and lift: if the door moves and the hinge cup or the mounting plate shifts with it, the fixing has let go and that is a real repair. Check whether the carcass itself is square before you blame the door — a base unit that has been packed badly on an unlevel floor will throw every door on it out, and a villa in Grey Lynn on original piles is not a flat floor.
The one case where you do not wait
Liquid water is a different animal from humidity, and the panel data says so explicitly. When board absorbs moisture the dominant effect is swelling in the thickness, and the industry guidance is blunt about the consequence: where that happens, there will be residual swelling after the product has dried out. It does not fully go back. Thickness expansion runs about 6% across the full humidity range and considerably worse with actual wetting, and 6% of an 18mm door is over a millimetre of thickness that was never in the design. Moisture-resistant board responds far more slowly and its residual swelling should be unnoticeable unless the panel gets a prolonged soaking — which is exactly why the sink and dishwasher runs should be MR board and why it matters whether your supplier actually specified it there.
So the diagnostic is simple. Seasonal swelling reverses. Water swelling does not. If the bottom 50mm of the door under the sink has gone fat, or the edgetape has lifted, or the face is bubbling away from the core, that door has been drinking and it is finished — and it will still be finished in February. Replace it, and find the leak first, because a new door on a live leak is money set on fire. If the rest of the run is sound, a door-and-drawer-front swap is materially cheaper than a new kitchen, and we have set out where the line sits between refacing and full replacement if you are weighing that up. For landlords with several properties showing the same thing, it is usually a spec problem rather than a run of bad luck, and worth handling as one portfolio-wide maintenance decision.
What goes wrong
- The July adjustment that becomes the February callback. One trip turns into two a year, forever, and the hardware wears out in the middle.
- Planing or sanding the edge to make it fit. The worst thing anyone does to a melteca door: you cut through the edgetape and expose raw core to a kitchen, and raw core drinks. It fits beautifully for one summer, then swells permanently along the cut. A planed door is a door you will be replacing.
- Replacing a perfectly good hinge. If a door binds in winter and runs in summer on that same hinge, the hinge is doing its job. The panel is the variable.
- Overtightening the adjustment screws. Particleboard holds a finite number of threads. Wind them hard twice a year and the cup eventually pulls — a sag you built yourself.
- Packing under the toekick to lift a binding door. You have thrown the carcass out of square to chase something that will be gone by October.
- Adjusting every door in the run to match the worst one. Now the whole kitchen is out by summer instead of one door being out in winter.
- Fixing the doors and ignoring the recirculating rangehood, the wet washing and the unflued gas heater. The kitchen is reporting a moisture problem; fixing the messenger does not fix the message.
- Assuming a bulging bottom edge is seasonal because it showed up in winter. Leaks show up in winter too. Residual swelling is the tell — go and feel it in February.
What to establish before anyone touches a screwdriver
- Did this door run cleanly last summer? If yes, and nothing has been spilled on it, you are looking at moisture and the answer is to wait.
- Is the gap even down its length, or does it wedge? Even is moisture. Wedged is a sag.
- Is the bottom edge thicker than the top when you run a finger across it? That is water, and waiting will not fix it.
- Is it worse than last July, or the same as last July? Same is a cycle. Worse is a fault.
- Does the rangehood duct outside, or blow back into the room? In a rental that is a Healthy Homes question before it is a kitchen question.
- Is washing being dried indoors, and is there a dryer vented outside? Up to five litres a load has to go somewhere.
- Is the carcass level and square, or packed up on an uneven floor? Fix the box before you chase the door.
- If it does need replacing, is the sink and dishwasher run specified in moisture-resistant board? If not, you will be back.
Frequently asked questions
Why are my kitchen cabinet doors sticking only in winter?
Because the board they are made from takes on moisture from damp air and grows. Melamine-faced particleboard and MDF change in length by roughly 0.03–0.06% for every 1% change in moisture content, which works out to around 0.3% across the full swing from dry air to damp air — about 3mm on a two-metre pantry door and enough to close a 3mm gap. In Auckland the swing is real and it is regional: NIWA's mean 9am relative humidity for Henderson is 80% in January and 92% in June and July, while coastal Leigh moves barely two points. Tall doors and pairs of doors go first because they have the most material to move.
Should I adjust my kitchen door hinges when they stick in winter?
Not if the door was fine last summer. Hinge adjustment is a fixed budget — a Blum CLIP top offers about ±2mm of side adjustment, +3/-2mm of depth, and ±2mm to ±3mm of height depending on the mounting plate. Spend a millimetre of that in July and the panel shrinks back in February, leaving the door visibly crooked and out of line with the rest of the run, so someone has to wind it back again. Two adjustments a year into particleboard eventually chews the screw threads and creates a genuine sag where there wasn't one.
How do I tell if my kitchen door is swollen or actually sagging?
Look at the shape of the gap and the history of the fault. Seasonal swelling closes the reveal evenly down its whole length, affects both doors of a pair, and looks the same this July as it did last July. A sag opens the gap as a wedge — tight at one corner, wide at the opposite one — affects heavy doors first, gets worse year on year, and does not care what month it is. If you lift the outer bottom corner and the hinge cup or mounting plate moves with the door, the fixing has let go and that needs repairing regardless of season.
Will leaving a sticking cabinet door alone over winter damage the kitchen?
Generally no, provided you are genuinely looking at seasonal movement and not water. A door that rubs its neighbour will mark the finish where they meet, and forcing a badly bound door can strain the hinge fixings, so ease off rather than slamming it. The thing that does damage kitchens is the intervention — planing the edge cuts through the edgetape and exposes raw core to kitchen moisture, which turns a temporary seasonal nuisance into a permanently ruined door.
Is a swollen kitchen door covered by warranty in New Zealand?
It depends entirely on the cause and on what your written warranty actually says, so read the document rather than assuming. A door that has moved within published board tolerances because the house it lives in is damp is a very different argument from a door that has delaminated on its own, and a door that has swollen because of a leaking waste under the sink is different again. Ask your supplier for the warranty terms in writing before you need them, and keep dated photographs of the gap in both winter and summer — that record settles most of these conversations quickly.
If it turns out to be the kitchen after all
Wait until February. If the doors have freed up, you never had a problem and you have saved yourself two callbacks and a set of chewed hinge screws. Put the effort into the ventilation instead — a rangehood that actually ducts outside, a dryer that vents, and a tenant who is not drying five litres of washing a load in the lounge. That is the fix. If the doors are still catching in late summer, then something has genuinely moved and it is worth a proper look: hinge fixings, carcass square, floor level, and whether the board on the wet runs was ever the right board in the first place.
That is where we come in. We have been manufacturing out of our own workshop in East Tamaki for 23 years and have put in over 2,000 kitchens across Auckland, so we have seen a lot of west and south Auckland doors in a lot of Julys, and we know which ones are the season and which ones are the spec. Send through the address, the unit count if it is a portfolio, and a couple of photos of the gaps — dated, ideally — and you will have a trade-priced number back inside 24 hours, plus GST, supply and install under one contract and one invoice. No showroom, so no showroom margin. If it is a door swap you will get a number for a door swap, not a sales pitch for a kitchen you do not need yet.