Long story short, this is the attempt that was made (not by me, so don't ask) at re-plastering a ceiling under uneven joists (natural sag, very old building). There's a mix of bonding and easifill 60 up there. How do I prepare this surface for multifinish? Also, do I need to skim the entire ceiling, or just the filled holes and plasterboard?
I am aware that there is a step where the plasterboard ends. I am planning on putting an LED strip profile there.