Video guide. This article accompanies a step-by-step YouTube tutorial on cleaning uPVC windows that demonstrates the right products and technique for frames, glass, and seals. Worth watching to see the method in action before you start.
1. Gather the right materials
You will need a dedicated uPVC cleaner (available from DIY stores and online), warm soapy water, a soft cloth or sponge, a non-abrasive cream cleaner for stubborn marks, a small brush or old toothbrush for the seals, and glass cleaner for the panes.
Do not use bleach, white spirit, abrasive pads, or anything solvent-based on uPVC. These products strip the surface sheen, cause the plastic to yellow, and can make it brittle over time. Cream cleaners are fine as long as they are not abrasive.
2. Start with the frames
Spray or apply the uPVC cleaner to the frame and wipe with a damp soft cloth. Work from the top of the frame downwards so dirty water does not run back over cleaned sections. For yellowing or green algae staining, apply the cleaner, leave it for a minute or two, and then wipe off.
For stubborn marks or ingrained dirt, apply a small amount of non-abrasive cream cleaner on a soft cloth and rub gently in a circular motion. Rinse with clean water and buff dry to avoid water marks.
3. Clean the glass
Wash the glass with warm soapy water and a soft cloth, then apply glass cleaner and buff off with a lint-free cloth or scrunched newspaper. Work in circular motions and finish with vertical strokes to catch any streaks.
On the outside, clean the glass before the frames so any run-off does not mark the freshly cleaned panes. On the inside, do the frames first since you are less likely to splash.
4. Clean the rubber seals
The rubber gaskets around the glass and the frame seals are often the dirtiest part of the window. Use an old toothbrush or small brush dipped in warm soapy water to scrub along the length of the seal. For mould or black staining, a diluted white vinegar solution works well — apply with the brush, leave for a minute, and wipe clean.
Once clean, run your finger along the seal to check it is still supple and making good contact with the frame. A dry, cracked, or flattened seal may need replacing to maintain the window’s draught-proofing and weather resistance.
5. Clear the drainage channels
uPVC windows have small drainage slots at the bottom of the frame to let condensation and rainwater escape. These can block with grime, dead insects, and debris. Use a small brush or a straightened paperclip to clear the slots. Blocked drainage channels cause water to sit in the frame, leading to mould growth and potential seal failure.
While you are there, check the weep holes on the outside of the frame — small holes or slots at the bottom edge of the outer frame. These should be clear of paint, dirt, and silicone.
6. Polish and protect the frames
Once the frames are clean and dry, apply a thin coat of uPVC restorer or plastic trim polish with a soft cloth. This fills minor surface scratches, restores a slight sheen, and helps repel dirt between cleans. Buff off any excess with a clean, dry cloth.
For white frames that have turned noticeably yellow, specialist uPVC whitening products are available, though the results vary depending on how far the discolouration has gone. Deep yellowing caused by UV degradation cannot be fully reversed and may indicate that the frames are approaching the end of their useful life.
When to call a handyman
Call Richard if the seals need replacing, the glass has misted between the panes (indicating a failed sealed unit), the frames are cracked or damaged, or the windows are stiff or no longer closing properly. These are jobs beyond a cleaning pass.
Need your windows maintained?
The Sandwich Handyman can clean, seal, and check your uPVC windows — keeping them weathertight and looking their best.
Contact Richard