Wall preparation is an important step when you in install tile on a painted wall.
How to install tile on plaster walls.
However tiling over tile can add quite a bit of thickness so make sure your wall can handle the weight.
You should not tile over wallpaper glossy surfaces lead paint or plywood.
One handy tip my father in law taught me three years ago was if you plan on tiling a wall and the wall is uneven then the plastering doesn t need to be abs.
Oil based paints can create a problem with tile installation consider removing this paint with paint remover or via sanding the paint away prior to installing the tile.
You may tile over existing tile painted or unpainted drywall plaster and textured walls.
If you re not sure if you have lead paint test kits are available.