Hi I want to repaint my external wall and fence wall too. The current paint was painted 2 years ago, still in good condition no flaking, I believe it's weatherbond nippon. So I want to ask whether I need to use primer? I plan to paint with solareflect, idea is to first water jet it to remove all loose dirt and mould/stains, then repait with 2 coats of nippon solareflect, just I'm not sure whether primer is needed if existing paint is still good?