dot and dab on stone barn walls France

[jondixon]

I am currently converting a large stone built barn in southern France.I wish to insulate the exterior walls with a plasterboard finish. As the barn is so big I was hoping to get away with using the dot and dab method to cover the walls.
in general the barn is dry and in good condition,with no signs of damp.
1. do I need to treat the walls in any way
2. will it work
3. what type of insulated plasterboard can I use for this method.
4. Is there an easier/quicker way-these walls are vast![/code]

[welsh brickie]

You can seal the wall first by pointing the wall and filling any holes,Then pva,wait for it to dry,then paint bitumin on the wall,I would not dot and dab directly to stone, any damp however small will travel through and ruin it.Usuall method is 2x2 stud then vapour barrier and plasterboard the insulation I normally use is drytherm,but you can upgrade to a celotex insulation if you want to..