Modern double glazing is low maintenance, not no maintenance. A little routine care keeps the frames looking new, the windows opening smoothly and the drainage working, and it protects the guarantees you paid for. This guide covers how to clean uPVC windows the right way, the yearly ten-minute service, what your guarantees actually cover, and how to tell harmless condensation from a failed sealed unit. Get the basics right and good uPVC frames comfortably reach the 20 to 25 years you should expect.
Routine care that keeps windows working
The frames need almost nothing beyond a wipe down. Use warm water with a drop of mild washing-up liquid and a soft cloth, then rinse and dry. That is it. The one rule that matters is what to avoid: never use abrasive cream cleaners, scouring pads or solvents such as white spirit on uPVC, because they scratch the surface, dull the finish and can leave permanent marks that no amount of later cleaning will remove. Clean the frames whenever you do the glass and they will keep their colour and finish for years. Gentle and regular always beats harsh and occasional.
The yearly ten-minute service
Once a year, give the moving parts a quick service. Lightly lubricate the hinges, handles and locks with a suitable light oil or spray so they keep operating smoothly and do not stiffen up or wear. Then check the drainage slots along the bottom of the frame, the small openings that let rainwater drain out of the frame, and clear any dirt, leaves or debris blocking them. Blocked slots trap water in the frame, which over time causes damp problems and can worsen condensation. Ten minutes a year on lubrication and drainage does more for the life of a window than any amount of aggressive cleaning.
What your guarantees actually cover
Guarantee lengths vary between firms, and that variation is a genuine buying signal: a longer guarantee usually reflects more confidence in the product and the fit. Frames commonly carry a 10-year guarantee, and some installers offer 15 years. Sealed glass units are often guaranteed for a shorter term, around 5 years, because the seal is the component most likely to fail over time. Knowing the split matters, because a failed sealed unit and a faulty frame are covered for different lengths.
| Component | Typical guarantee | What it covers |
|---|---|---|
| uPVC frame | 10 years (some 15) | Frame defects, warping and discolouration |
| Sealed glass unit | About 5 years | Seal failure, misting between the panes |
| Workmanship (via IBG) | Matches the installer's guarantee | Stays valid even if the installer stops trading |
Guarantee lengths vary by installer. Always confirm the exact terms in writing before you buy.
Why the Insurance-Backed Guarantee matters most
A company guarantee is only ever as good as the company behind it. If the installer goes out of business, an ordinary workmanship guarantee dies with them, and you are left with no one to call when something goes wrong. This is what the Insurance-Backed Guarantee, or IBG, is for. A FENSA or CERTASS registered installer buys an IBG so that your workmanship guarantee stays valid even if the firm stops trading, with the insurer stepping in to honour it. It is closely tied to why a FENSA registration is worth insisting on. Without an IBG, a company guarantee is worth nothing the day the firm folds, so ask whether one is included before you sign.
The question I wish every customer asked me is whether the guarantee is insurance-backed. A ten-year promise from a firm that shuts in year three is worth nothing. The IBG is the bit that survives the company, and it costs the installer very little to include, so there is no good reason to leave it out.
Tom Bradley, FENSA-registered installer
Condensation: aftercare or a claim?
Condensation is the aftercare question people worry about most, and the answer depends on where it is. Condensation on the inside face of the glass is almost always a ventilation and humidity issue in the room, not a fault with the window. It clears with better airflow, use of the trickle vents and cutting down moisture from cooking, showering and drying washing indoors. Condensation trapped between the two panes is a different story: it means the sealed unit has failed and let moisture in, which is a genuine fault and a guarantee claim if the unit is still covered. The good news is the glass unit can usually be swapped without replacing the whole window. Our guide to condensation on double glazing works through each case, and if a unit has failed the repair versus replace comparison helps you decide whether to swap the unit or the window.
Frequently asked questions
Use warm water with a little mild washing-up liquid and a soft cloth. Wipe the frames down, rinse and dry. Never use abrasive creams, scouring pads or solvents such as white spirit, because they scratch and dull the uPVC surface and can leave permanent marks. Gentle and regular beats harsh and occasional.
Clean the frames whenever you clean the glass, and give the moving parts a proper service once a year. That yearly job means lightly lubricating the hinges, handles and locks, and clearing the drainage slots at the bottom of the frame so water can escape. Ten minutes a year keeps the windows opening smoothly and draining properly.
Guarantee lengths vary and are a useful buying signal. Frames commonly carry a 10-year guarantee, and some installers offer 15 years. Sealed glass units are often guaranteed for a shorter term, around 5 years, because the seal is the part most likely to fail over time. Always check the guarantee split before you buy.
An Insurance-Backed Guarantee (IBG) is a policy a FENSA or CERTASS registered installer buys so that your workmanship guarantee stays valid even if the installer stops trading. Without an IBG, a company guarantee is worth nothing once the firm folds, because there is no one left to honour it. It is one of the most important things to check.
Not usually. Condensation on the inside of the glass is normally a ventilation and humidity issue in the room rather than a fault with the window. Improving airflow, using trickle vents and reducing moisture from cooking, drying and bathing usually clears it. It is an aftercare issue, not a guarantee claim.
Condensation trapped between the two panes of glass means the sealed unit has failed and let moisture in. That is a genuine fault, not something you can wipe away, and it is a guarantee claim if the unit is still covered. The glass unit can usually be replaced without changing the whole window.