If your paint job is failing, or if it is old or otherwise untrustworthy, it needs to be stripped completely off the wall before painting (or any other refinishing). Painting or wallpapering on top of old or failing paint is doomed to disaster: when the old paint peels off the surface, it will take the brand new coating with it. Old paint needs to be stripped from walls and ceilings before repainting, wallpapering, or staining, in order to ensure proper adhesion and a long-lasting result.
That said, stripping paint can be a tricky and delicate process; you need to get it all off, but you also don’t want to apply so much pressure or chemicals that the underlying wall is damaged. Blue Door Painters will carefully strip old paint from walls and ceilings without damaging the underlying substrate, leaving that surface clear and ready for refinishing.