PVC window maintenance
A PVC window asks for very little: wash it, keep the drainage clear, lubricate the hardware. What ruins a profile is almost never neglect — it is the wrong product.
The minimum routine
Four things a year. There is nothing else to do on a PVC window — anyone selling you an annual maintenance contract for one is selling you something else.
Wash the frame
A soft cloth and lukewarm water. If it is properly dirty, add a neutral detergent — then go over it again with clean water so no film is left behind. That is all the cleaning the profile needs: the PVC surface is hard and smooth, with no pores for dust or spores to cling to, which is why it never needs painting or varnishing the way timber does.
Vacuum the rebate and clear the drainage
With the sash open, vacuum the channel between sash and frame: it collects dust, plant debris and insects. While you are there, check that the drainage holes along the bottom of the frame are clear. If one is blocked, clear it with a wooden toothpick — never with wire or anything metal, which scores the channel and ruins the seal.
Lubricate the hardware
The moving parts — locks, stays, rollers — take an acid-free, resin-free oil or grease, ideally a spray that reaches the hidden points. It is the difference between a window that still closes with two fingers at twenty years old and one that needs a shoulder at eight.
Care for the gaskets
The seals sit in the rebate of frame and sash — and, in centre-seal systems, along the middle of the profile and both sides of the glazing too. A dedicated gasket product keeps them supple; a dried-out gasket stops compressing, and that is when the draughts come back.
What never to use on the profile
Most of the damage we see on PVC profiles does not come from neglect: it comes from someone scrubbing enthusiastically with the wrong product. PVC cannot be repainted, so a scratch or a solvent mark is there for good.
They scratch the surface. PVC cannot be repainted: the scratch stays, and from then on dirt collects in it.
Aggressive solvents attack the profile surface. The damage may only show months later, when nobody connects the two events.
Heat and pressure distort the surface and stress the seals.
Those are recipes for paintwork or crockery, not for PVC. VEKA, the profile manufacturer, warns against them explicitly.
Profiles with a coloured or woodgrain foil need different products from plain white ones. Always check what you are buying.
One rule covers it: if the product is meant for unblocking drains, degreasing ovens or stripping varnish, it is not meant for your window.
The white has yellowed: dirt or the profile itself?
It is the most searched question about PVC windows in Portugal, and the honest answer depends on something you cannot see: what is inside the material.
Quality white PVC contains ultraviolet stabilisers based on titanium dioxide. They are what stop sunlight from degrading the material and turning it yellow — and why profile manufacturers give colour warranties measured in decades rather than years. A profile made without those stabilisers, or with too little of them, yellows in the sun, and no cleaning product brings it back: the colour changed in the material, not on the surface.
Before scrubbing hard, run the simplest test there is: wipe a discreet corner with a damp cloth and neutral detergent. If the tone lifts, it was dirt. If it does not, it is the profile, and scrubbing harder will only scratch what cannot be undone.
It is also why the profile brand appears on our quotes. A cheap frame of undefined origin costs less on day one and shows the difference precisely here, around the eighth summer.
Homes by the sea: salt changes the arithmetic
In a house facing the sea the PVC profile is still not the problem — it does not corrode in salt air, which is one of the reasons we recommend it on the coast. What suffers is the metal: locks, stays and rollers pick up salt spray and seize years earlier than they would inland.
In the homes we work on in Cascais, in the old town of Sesimbra and in Colares, the sensible routine is double the usual: wash the profile every three months so salt does not settle, and lubricate the hardware once or twice a year. In second homes that stand closed for months, the practical moment is the first visit of the season — before the window turns stiff, not after.
When it is no longer maintenance
Some symptoms no routine will fix, and it is worth telling them apart so you do not spend an afternoon with cloths and sprays on a different problem altogether:
Air still comes in after lubricating and cleaning
→ Dried-out gaskets (replaceable) or a warped frame (not adjustable)
Mist between the two panes that will not wipe away
→ The sealed unit has failed: the glass is replaced, not the frame
Condensation and mould around the opening, but not on the glass
→ A thermal bridge in the reveal or the shutter box, not the window
If you recognise the first case, the guide to the signs you need new windows helps you work out whether repairing or replacing pays off.
Frequently asked questions
Modern white PVC contains UV stabilisers based on titanium dioxide, which prevent yellowing. That is why profile manufacturers give colour warranties measured in decades. What does go yellow is profile made without those stabilisers, or with too little of them — typical of cheap profile of uncertain origin — and no amount of cleaning will bring it back: the colour has changed in the material, not on the surface. Before scrubbing hard, try a damp cloth on a discreet corner: if the tone lifts, it was dirt; if it does not, it is the profile.
Lukewarm water and a soft cloth handle 90% of cases. For stuck-on dirt, a pH-neutral detergent or a PVC-specific product recommended by the profile manufacturer, then a rinse with clean water. What matters is not the brand but what the product lacks: nothing abrasive and no solvents.
Clean it off straight away. VEKA singles out sunscreen and mineral fertiliser dust as two substances that can permanently alter the profile surface if left on it. Washed off the same day they leave no mark — one of the few cases where speed matters on a PVC window.
On the coast, salt settles on the profile and especially on the hardware. In homes facing the sea — our experience is in Cascais, Sesimbra and Colares — it makes sense to double the routine: wash the profile every three months so salt does not build up, and lubricate the hardware once or twice a year. PVC does not corrode in salt air, which is one reason we recommend it on the coast, but the metal hardware does.
You can, and it is a cheap repair when the frame is still straight and the hardware works. It deals well with a localised draught. It does not fix cold coming through single glazing or a warped frame — in those cases it postpones rather than repairs. The <a href="/en/guides/signs-you-need-new-windows/">signs guide</a> helps tell the two apart.
Often yes, and a spray on the moving parts sorts it. If it stays stiff after lubricating, or the sash rubs against the frame, the issue is adjustment: the hardware has regulating screws that compensate for clearance and for the frame settling. It is minutes of work for someone with the right key who knows where to turn.
No. If the mist is between the two panes and will not wipe away, the sealed unit has lost its seal and the insulating gas has escaped. It is not dirt and it is not repairable: the glass unit is replaced, often without touching the frame.
A quality profile lasts in the order of 40 to 50 years, and the hardware is the part that most repays annual lubrication. With no maintenance at all the window will not fall out — it will simply get stiff and seal worse, letting air through long before the material itself is spent.
Window no longer closing the way it used to?
Adjustment, gaskets or replacement — we tell you which it is before selling you the most expensive one.