Twenty-year-old uPVC windows sometimes look duller or yellower than they used to. Usually more can be done about that than people think, and sometimes replacing them is the wiser choice. Here are the options, from light to heavy.
First: what exactly is going on?
- Green or black film: algae and dirt on the north side or under trees. Easy to remove.
- A dull, chalky layer: weathering of the top layer by UV. Usually still repairable.
- Genuine yellowing: the material itself has discoloured. This is permanent.
- Scratches and scuff marks: often caused by scouring pads or a pressure washer.
Step 1: a thorough clean
Always start here, because in nine cases out of ten it is simply dirt. Rinse first with plenty of lukewarm water, then wipe down with a soft sponge and mild soap, and rinse again. For green film, a solution with a little soft soap or a dedicated uPVC cleaner works well. Let it soak in for a moment and do not rub it dry.
Step 2: a uPVC cleaner for the dull layer
If the frame stays dull, use a cleaner made specifically for PVC (from a builders’ merchant or through us). That takes off the weathered top layer. Test on an inconspicuous spot first. The underside of the sill, for instance. And use nothing more aggressive than you need.
Stay away from: scouring powder, steel wool, acetone, thinners, bleach and the pressure washer. Those make the problem permanently worse, because they abrade the smooth top layer. Underneath is porous material that then soils even faster.
Step 3: aftercare
After a thorough clean you can treat the surface with a PVC conditioner or a thin layer of car polish without abrasives. That brings the shine back and makes the frame dirt-repellent for a while. Repeat once a year.
Does painting work?
There is special paint for uPVC, and it can be done. But be honest about what you get: you trade a maintenance-free frame for a painted one that you have to keep maintaining from then on. And where there are cracks or lifting foil, paint is no solution either. We usually advise against it.
When is replacing wiser?
Restoring makes sense as long as it is only about appearance. Replacing is worth considering if:
- the glass is misted up on the inside. In which case the insulation value has gone anyway
- the frames are draughty or stiff to close and adjustment no longer helps
- you still have old double glazing: going from 2.8 to 1.1 W/m²K makes a noticeable difference to your heating costs
- you are renovating anyway. Then you take it all on at once, ISDE subsidy included
Not sure whether your windows are still worth restoring? Send us a photo or have our surveyor take a free look. We will simply say so if cleaning is enough.
Curious what it would come to for you?
Request a no-obligation quote or book a free measuring visit. Our own surveyor comes round, takes the measurements and advises you on the spot, you are under no obligation.