Skimming

[mleroux21]

I am going to skim the walls of my bathroom so I have a nice flat non textured look to the walls. My only question is do I need to rough up the walls before I skim the wall, or can I skim right on top of the painted walls? Thanks for the help.

[SteveH]

If it's gloss paint then sand it down..no need to sand for flat paint but do it anyways because the job is better.