How do I paint UPVC or tiles?

Why these surfaces reject ordinary paint, the primers that make it stick, and where it is worth doing at all.

Difficulty: intermediate
Time: 5 hr
Read: 4 min
Safety: warning

Short answer

Both are non-porous, so the whole job is adhesion. Degrease thoroughly, abrade the surface, then use a primer made specifically for UPVC or for tile. Ordinary paint or a general primer will peel off in sheets within months.

Painting plastic and glazed ceramic is entirely a preparation problem. The paint will do its job; the question is only whether anything holds it to a surface designed to be wiped clean.

Safety

Specialist primers for UPVC and tile are usually solvent-based and need real ventilation and a suitable respirator, not a dust mask. Keep them away from naked flames and pilot lights. Painting UPVC windows in a rented or leasehold property, or on a listed building or in a conservation area, may need permission — check before starting, because it is difficult to reverse.

Step by step

Decide whether it is the right answer.Painted UPVC and tile are a compromise: they look good for years rather than decades, and they are difficult to reverse. For tiles in a shower, regrouting or replacing is often better. Worth thinking through first.
Check permissions on UPVC windows.Rented and leasehold properties frequently prohibit it, and listed buildings and conservation areas have their own controls. Painting external windows is hard to undo.
Degrease everything, twice.Sugar soap or a proper degreaser, then a clean water rinse, then let it dry. Bathroom tiles carry soap residue and silicone from cleaning products, and UPVC has mould-release agents and years of atmospheric grime. This is where most failures start.
Abrade the surface.Fine abrasive pad or 240 grit paper until the sheen has gone uniformly dull. You are creating a mechanical key. A missed shiny patch is exactly where the paint will lift first.
Wipe off the sanding dust with solvent.Methylated spirit or isopropyl alcohol on a lint-free cloth. Water leaves residue and a damp surface, and dust under primer defeats the abrading you just did.
Use the correct specialist primer.An adhesion primer sold specifically for UPVC, or a tile primer for glazed ceramic. This is not a step where a general-purpose primer will do — it is the entire basis of the job.
Repair the substrate before priming.Chips in tile filled with an epoxy filler, cracked grout raked out and replaced, and any failed silicone cut out and renewed after painting.
Apply thin coats.Two or three thin coats rather than one thick one, with the stated drying time between. Thick coats on a non-porous surface stay soft underneath and mark for weeks.
Use a foam roller or spray for a smooth finish.A short-pile foam roller leaves the least texture on a flat surface. Brush marks are very visible on tile and gloss UPVC.
Work in the right conditions.Warm, dry, low humidity, out of direct sun. These paints are fussier than emulsion and a cold damp bathroom is the worst case for them.
Allow the full cure, not just drying.Touch dry in hours, fully hard in days to a fortnight. Using a shower or wiping a windowsill too early is what causes early failure.
Renew the silicone last.Cut out the old sealant, paint, let it cure, then reseal. Painting up to old silicone gives an edge that peels.
Expect to maintain it.Painted tile in a shower and painted UPVC in weather both need touching up. Treat it as a finish with a service life rather than a permanent change.

Tips

Degrease, abrade, degrease again. Adhesion is the whole job and every failure traces back to one of those three.
Buy the primer made for the actual substrate. A general multi-surface primer is not the same thing and it is where the money is saved and the job is lost.
Avoid painting tiles inside a shower enclosure if you can. Constant hot water and abrasion is the hardest possible test for any coating.

Common mistakes

Using a general-purpose primer — UPVC and glazed tile are non-porous, and only an adhesion primer formulated for them will bond. Ordinary primer peels off in sheets within months.
Skipping the degrease before abrading — Sanding grinds the grease into the surface instead of removing it. Degrease first, abrade, then degrease again.

If it doesn't work

Paint peeling in sheets

Cause: Wrong primer, or inadequate degreasing — Fix: It has to come off back to the substrate and be redone properly. Patching over failed adhesion does not hold.

Paint marks easily weeks later

Cause: Not fully cured, or coats applied too thick — Fix: Allow the full cure time before use — up to a fortnight on some products. Thin coats next time.

Brush marks very visible

Cause: Brush application on a flat non-porous surface — Fix: Use a short-pile foam roller or spray, and thin the paint slightly if the product allows.

Lifting along the silicone edge

Cause: Painted up to old sealant — Fix: Cut out the silicone, tidy the paint edge, and reseal once cured.

Yellowing on white UPVC

Cause: Some paints yellow in low light, or the wrong exterior product — Fix: Use a UPVC-specific exterior paint rated for UV. Yellowed paint has to be repainted.

Questions people ask

Can you paint UPVC windows?

Yes, with a UPVC-specific adhesion primer and paint. Degrease, abrade to a uniform dull finish, degrease again, then prime. Check permissions first on rented, leasehold or listed properties.

Does painting tiles actually work?

It does, with a proper tile primer and full preparation, but treat it as a finish with a service life rather than a permanent change. Avoid it inside a shower enclosure where possible.