Plasterboard preparation

[Talifer]

I've been living in my new build home for a year now and want to start decorating, I was advised not to wallpaper or paint for a year to let the house dry out.

My first task is to wallpaper a feature wall, but I'm a little unsure of how I should prepare the surface. As I understand, the plasterboard has a paper surface and wallpapering directly onto this would cause problems should I wish to remove it at a later stage. However all the advise seems to assume you're working from a clean slate whereas my walls were painted by the builder before I moved in. What I really want to know is should I treat it as if the paint did not exist, it's a water based paint "to allow the wall to breath" and I would imagine the builders wouldn't have primed/sealed the plasterboard before hand (that would eat into profits). Alternatively can the paint be considered a primer/sealer? Should I paper straight over the paint? Should I just buy some sealer and cover the paint?

Any advise would be appreciated
Thanks

 

[joe-90]

You can paper straight over it, but if funds allow, buy a tin of Zinsser Gardz.

 

[Bosswhite]

I assume it is painted with Emulsion at the moment, just size the wall according to the instructions on the wallpaper paste and the hang the paper the next day.