Can I plaster over paint on an external wall of a house?
Yes you can paint the wall and plaster it at a latter date,but when you do plaster it you will have to give it a coat called a scud.You make a really wet mix of sand and cement,so its almost like water,and what you do is flick this mix all over the wall so it acts as grip for the finish coat.To be honest you might need 2 coats,1 is a scud and 2 is a scratch to really get a grip on the painted wall.The scratch is stiffer than the scud so you need to put it on with a hawk and trowel after the scud has been left to set for at least a day.Then put your finish coat over the scratch and finish in whatever style you like.This is a guide for a sand and cement render mix but if you are dashing the wall then all you will need is a heavy scud for the dash.I have been plasterind for 6 years!
