How much weight can you mount to a wall?
(Apologies for asking here whilst not a serious DIYer, but as a Stack Overflow user it seemed like the obvious place!)
I would like to add some shelves to a wall in my house, but as the wall is only plasterboard, I am aware that the shelves won't be able to take much weight. By knocking I can only detect a wooden baton behind one end, so I suspect the other end of the shelves would just have to screw into the plasterboard with nothing behind it.
Is there a good rule of thumb for estimating how much load the shelf would be able to take (e.g. kilograms per shelf bracket or somesuch), and if so, is there any extra information I need in order to calculate it (e.g. thickness of plasterboard)?