Why Is My uPVC Paint Peeling?
Plastic gives paint nothing to grip unless you prepare it.
uPVC is made to shrug off dirt and water, which is exactly what makes it tricky to paint. It is smooth, non-porous and often carries residues that stop paint bonding. When paint peels from uPVC, the cause is nearly always one of a few things: the frame was not cleaned and keyed properly, the plastic was too new, the paint was not made for plastic, or the weather was wrong on the day. The cure is never another coat on top. Here is how to put it right.
At a glance
- Peeling uPVC paint is an adhesion problem; another coat will not fix it.
- New uPVC needs at least twelve months outdoors before it is painted.
- Degrease every surface, then key it lightly with fine abrasive.
- Paint on a dry, still day between 10°C and 25°C, out of strong sun.
- Use a flexible paint made for uPVC and composite, never on wooden frames.
Why paint lets go of uPVC
Residue, new plastic, no key, or wrong paint.
Most uPVC peeling comes down to the surface. Traffic film, cleaning products, silicone sprays and polish leave an invisible layer that paint bonds to instead of the plastic. Brand new uPVC still carries mould-release agents and plasticisers from manufacture, which is why it needs at least twelve months of weathering before it will take paint. A smooth frame that has only been wiped, not keyed, gives paint very little to hold.
The paint matters too. Rigid paints made for wood or metal cannot cope with the way plastic frames expand and contract through the seasons, and crack or lift around corners and joints. Paint taken onto flexible gaskets, silicone or moving contact points tears away the first time the window opens.
The day you painted
Rain, dew, cold or hot sun spoil adhesion.
Exterior paint needs the right conditions to bond and dry. Rain or dew on a fresh coat, a cold morning when the frame is below 10°C, or full sun heating a dark door well above the air temperature can all weaken the finish. Choose a dry, still day between 10°C and 25°C with no rain forecast, and work around the house so you are not painting in strong direct sun.
How to fix peeling uPVC paint
Remove the failed paint, prepare properly, then repaint.
Remove all loose and poorly bonded paint: if it lifts easily with a plastic scraper or a strip of tape, it has to go. Be kind to the plastic itself and avoid harsh solvents and coarse abrasives. Then wash every surface, including drainage channels and the underside of sills, with sugar soap, rinse with clean water and let it dry completely.
Key the frames with 320 grit until the sheen is uniformly dull, using a sanding sponge on beading and woodgrain texture, and remove every trace of dust with a microfibre cloth. Mask the glass, gaskets and hardware, then apply two thin coats, 1–2 hours apart. Leave doors and windows open for at least 4 hours afterwards, and treat the finish gently for 7 days.
How our uPVC & Composite Paint helps
Flexible, self-priming and made for plastic surfaces.
Our uPVC & Composite Paint is a flexible, UV-resistant exterior coating made for plastic and composite. On correctly cleaned and keyed uPVC that has weathered for at least twelve months, and on degreased, lightly keyed composite skins, it is self-priming: no separate primer. Full adhesion develops over the 7-day cure, so the fresh finish is fragile at first.
Be clear about what it is not for. It is flexible, not breathable, and it is not suitable for wooden windows or doors; timber frames need a coating made for exterior wood. If your windows or doors are still under a manufacturer guarantee, check whether painting affects it before you start.
Sample it the way we would
Step 1
Paint your peel-and-sticks
Each £5.99 sample comes with three paintable peel-and-sticks. Give them two coats and let them dry fully.
Step 2
Stick them around the room
Put them on two or three walls, including the wall opposite the window, at eye level and lower down.
Step 3
Live with them for a day or two
Look in the morning, the afternoon and under your evening lamps. Move them around until you are sure.
Your questions, answered
Can I paint over peeling uPVC paint?
No. Remove the loose paint first; anything you paint on top is only as secure as the layer underneath it.
Why is paint peeling off my new uPVC door?
If the uPVC itself was new, residues from manufacture were probably still on the surface. uPVC needs at least twelve months outdoors before painting. Composite skins do not need weathering, but they must be degreased and lightly keyed.
Do I need a primer on uPVC?
Not with our uPVC & Composite Paint, which is self-priming on correctly prepared, weathered uPVC. Preparation does the job a primer would otherwise do.
Can I use uPVC paint on wooden windows?
No. Our uPVC & Composite Paint is flexible, not breathable, and is not suitable for wooden windows or doors.
Keep exploring
Why Is My Paint Peeling? Causes and Fixes
Paint rarely fails on its own. Find the cause, and the fix lasts.
Why Is My Paint Cracking or Bubbling?
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