Quick answer: Wipe frames and sills with warm soapy water and a soft cloth, then rinse and dry to avoid watermarks. For stubborn grime or yellowing, use a mixture of one part white vinegar to four parts warm water, leave for ten minutes, then wipe clean. Never use bleach, scouring pads, nail varnish remover, or methylated spirits, since these can scratch or dull the glossy finish.
UPVC windows are prized for being low maintenance, since they do not rot or rust the way wood or aluminium can. That does not mean they stay clean on their own though, and the wrong cleaning product can permanently dull a finish that would otherwise last for decades.
What You Will Need
- A bucket of warm water
- Mild washing-up liquid, or a specialist uPVC cleaner
- A soft cloth or sponge
- A soft-bristled brush or old toothbrush, for crevices and joints
- White vinegar, for stubborn marks
- A dry microfibre cloth
What to Avoid
Certain products can permanently damage uPVC’s glossy finish, so steer clear of bleach, cream cleaners, white spirits, nail varnish remover, methylated spirits, and abrasive scouring pads. These can scratch the surface or strip away the sheen, and unlike dirt, that kind of damage cannot be cleaned away afterwards.
Step 1: Clean the Frame and Sill
- Remove loose dust and debris with a dry brush or cloth, then vacuum into any corners where dirt tends to collect.
- Mix warm water with a squirt of mild washing-up liquid in a bucket.
- Wipe down the frame and sill with a soft cloth or sponge, working from top to bottom.
- Rinse away soapy residue with clean water on a fresh cloth.
- Dry thoroughly with a soft, dry cloth to prevent watermarks forming as it air dries.
Step 2: Tackle Stubborn Stains or Yellowing
If soapy water alone does not shift built-up grime or yellowing, particularly on older white uPVC exposed to a lot of sun.
- Mix one part white vinegar with four parts warm water.
- Wipe or spray the solution onto the affected area and leave it to sit for around ten minutes.
- Wipe away with a clean, damp cloth, then rinse with plain water.
- For particularly stubborn stains, a paste of bicarbonate of soda and a small amount of water can be applied, left for a few minutes, then gently scrubbed with a soft brush.
Step 3: Clean the Glass
- Use a standard glass cleaner, or make your own with a tablespoon of white vinegar mixed into two litres of water.
- Spray the solution onto the glass and wipe clean with a soft cloth or, for an old-fashioned but effective finish, scrunched-up newspaper.
- Buff dry with a clean, dry cloth to avoid streaks.
Step 4: Clean the Hinges and Moving Parts
Hinges are often overlooked because they are harder to reach, but neglecting them can eventually make windows stiff to open.
- Fully open the window to expose the hinge mechanism.
- Use a vacuum nozzle fitted with a soft dusting brush to remove dust and debris without scratching the surrounding area.
- Apply a few drops of a light multi-purpose oil to the hinge itself to keep it moving smoothly, but avoid getting oil on the surrounding uPVC frame or glass.
Step 5: Clean the Rubber Seals
The rubber seals around the window keep out draughts and water, and need gentle care to stay effective.
- Wipe them with a soft cloth and mild soapy water, avoiding any pulling or stretching of the rubber.
- Apply a light silicone spray occasionally to keep the seals supple and prevent them cracking over time.
Step 6: Clear the Drainage Holes
Small drainage holes at the bottom of the frame allow rainwater to escape rather than pooling inside the frame cavity. These are easy to overlook but important to keep clear.
- Locate the drainage holes along the bottom of the frame.
- Use a cotton bud or a small stick to gently clear away any dirt, leaves, or debris blocking them.
- Check them periodically, particularly after autumn when leaves and debris are more likely to collect.
A Note on WD-40 and uPVC
You may see conflicting advice about WD-40 and uPVC windows. The distinction is where it is used: a drop of light oil on a stiff hinge mechanism is fine and often recommended, but WD-40 and similar products should never be sprayed directly onto the uPVC frame or glass surface itself, since it can affect the finish.
How Often Should You Clean uPVC Windows?
A quick wipe with warm soapy water every few weeks keeps grime from building up. A more thorough clean, including hinges, seals, and drainage holes, is worth doing every few months, or at least twice a year alongside your general window cleaning routine.
Related Guides
- How to Clean Windows Without Streaks (for a streak-free finish on the glass itself)
- How to Draught Proof a Door
Frequently Asked Questions
Why has my uPVC window frame turned yellow?
Prolonged sun exposure and general ageing can cause white uPVC to yellow over time, particularly on south-facing windows. A vinegar and water solution or a specialist uPVC cleaner can often restore some of the original brightness.
Can I use vinegar to clean uPVC windows safely?
Yes, a diluted vinegar solution is a safe and effective way to tackle stubborn grime and mild yellowing on both the frame and glass, without the risk of damage that harsher chemicals carry.
What should you never use to clean uPVC windows?
Avoid bleach, cream cleaners, white spirits, nail varnish remover, methylated spirits, and abrasive scouring pads, all of which can scratch or dull the glossy finish permanently.
How do I clean uPVC window drainage holes?
Gently clear them with a cotton bud or a thin stick to remove any dirt, leaves, or debris, checking periodically so water can continue to drain away properly rather than pooling in the frame.
Final Thoughts
Keeping uPVC windows looking their best comes down to regular warm soapy water cleans and steering clear of the handful of products that can permanently dull the finish. A little extra attention to the hinges, seals, and drainage holes a few times a year will keep the whole window working smoothly, not just looking clean.