What actually wears on a uPVC window
The material is the reason people choose uPVC: it does not warp in monsoon damp, corrode in salt air, attract termites or need repainting. So when a uPVC window stops working well, it is almost never the frame.
Gaskets. The EPDM seals the sash compresses against. They harden with heat and UV and stop springing back. This is the most common cause of draughts, dust and creeping road noise, and the cheapest thing on the list to fix.
The multi-point gearbox. The mechanism inside the sash that drives the locking cams. It is a wear item with a finite number of cycles. When it fails, the handle turns without locking — and because the cams also pull the sash onto the gasket, the window stops sealing at the same time.
Hinges and friction stays. They wear, and their fixings can loosen in the profile. A dropped sash is the usual symptom.
Rollers, on sliders. Covered in detail under sliding window service.
Drainage slots. Silted up, and the reason water appears on the sill.
Reinforcement: the thing you cannot see
uPVC profiles are hollow and multi-chambered. Over any meaningful span they rely on galvanised steel inside the chambers to carry load and resist wind.
When a uPVC window sags, bows or feels flexible, the usual cause is that the steel was omitted or under-specified for the span. This is a fabrication decision made years earlier and is invisible from outside. We check it before re-hanging a sagging sash, because adjusting the hinges on an under-reinforced frame just moves the problem.
It is also the main reason a cheap uPVC window and a good one look identical in a showroom — see best uPVC windows in Mumbai for what to ask.
Discolouration, honestly
White uPVC exposed to years of direct Mumbai sun will yellow. This is surface degradation of the polymer, not dirt. It cannot be cleaned off, and restoration products give a short-lived cosmetic improvement at best.
What we can do is replace individual affected components, or — if the whole elevation has gone — discuss replacement with a foiled or laminated profile, which holds colour far better. See colour options.
Welds and corners
uPVC frames are heat-welded at the corners, so the weld is the joint. A corner that has opened cannot be reliably re-welded in place, and the affected sash or frame section is normally replaced while the rest of the window stays.
This is rare on a well-made frame and common on one that was under-reinforced for a wide opening.
What a uPVC service visit includes
Drainage cleared and flow-tested; gaskets inspected and replaced where failed; hinges, stays and rollers lubricated and adjusted; gearbox and handle tested for full lock engagement; fixings checked; glazing beads and sealed units inspected; every sash operated through its range.
Replacement hardware is matched to the profile. Where a proprietary part is obsolete we say so up front, because that changes the repair-versus-replace answer.
See the full service and repair range, or scheduled maintenance if you would rather this happened on a calendar than after a leak.