You can paint over most gloss doors with good results, but the level of finish you can achieve depends on a few factors. These include what the door is made from, how old the gloss paint is, and what condition it is in.
It is best practice to sand down timber doors to remove the old gloss paint before repainting. This will give you the best finish. However, old gloss paint can be painted over with new paint if the old paint is in good condition.
UPVC and composite doors
Unlike timber doors, UPVC and composite doors that leave the factory with a gloss finish aren’t designed to be sanded. These doors can be painted over with new paint. Filler can be used to fill scratches and mend surface defects before painting.
General rules and notes