i had my rooms all re skimmed 2 years ago and noticed
some cracks appearing on some of the plaster in the rooms
and the hall.whats causing the cracking.
Most likely shrinkage, Mick. It all rather depends on what's underneath the skim. The previous plaster might have lost its "key", and is moving around a bit. If any areas sound hollow when you tap them, then they may need re-doing............. otherwise just use a flexible filler.