How long do upvc windows last is a question with several answers, because a window is not one thing. The profile, the sealed units, the gaskets and the hardware age at different rates, and in most houses the window is replaced long before the plastic itself has anything wrong with it. Knowing which component is failing is what decides whether you are booking a glazier for an afternoon, an engineer to adjust the hardware, or a whole house replacement.
The hardware usually goes first
Hinges, locking mechanisms, handles and friction stays are moving metal parts under load, and they are the first things on a uPVC window to complain. Sashes that drop, that need lifting to lock, that catch on the frame or that will not stay open are hardware symptoms rather than frame symptoms. Almost all of it is replaceable, most of it is a routine call out for a window engineer, and doing it is a fraction of the cost of a new window. A house whose only complaint is stiff handles does not need replacing.
The sealed units go next
The edge seal of a double glazed unit degrades slowly and eventually lets moist air into the cavity, which shows as misting between the panes. This is the commonest genuine failure in an ageing window and it is not a frame problem. If the frames are sound, replacing the units restores the window, improves it if the new units are better specified than the originals, and leaves everything around the opening undisturbed.
The gaskets and seals are consumable
The rubber gaskets that seal sash to frame harden, shrink and lose their grip over the years, which shows up as draughts, whistling in wind and rain getting past the closed sash. Gaskets are replaceable and cheap, and doing them alongside a hardware service will often make an old window feel a great deal newer. This is the maintenance most uPVC windows never receive, largely because they were sold as maintenance free.
The profile itself outlasts all of it
What does eventually happen to the plastic is cosmetic and structural at the margins: yellowing or chalking of white profiles on sunny elevations, and welded corners that eventually work loose on frames that have carried heavy sashes for decades. A frame that has visibly dropped out of square, or where the corner welds have opened, is genuinely at the end. That is a different observation from a frame that simply looks tired, and it is worth having somebody competent say which yours is.
The reasons people replace early
Most whole house replacements happen for reasons other than failure. Older units were often fitted without the coatings and fills that are standard now, so a house full of working twenty year old windows can still be losing far more heat than it needs to. Appearance changes too, and a house being sold or extended often gets new windows to match. Those are legitimate reasons, but they are choices rather than necessities, and it is worth being clear which one you are making before agreeing to a whole house price.
Other questions people ask
Do uPVC windows really need no maintenance?
They need no painting, which is what the phrase originally meant. Gaskets, hinges, locks and drainage slots all benefit from attention, and windows that get it last noticeably longer than windows that do not.
Can yellowed white uPVC be restored?
Cleaning and specialist restorers help with surface staining. Deep discolouration is in the material rather than on it. Spraying is offered as an alternative to replacement and its longevity depends heavily on preparation and product.
Is it worth servicing old windows rather than replacing them?
If the frames are square and sound and the complaints are draughts, stiffness or misting, yes, and it is much cheaper. If the frames have moved or the welds have opened, servicing is money spent on a window that is going anyway.