I replastered my daughter's room and you're right, I could never get it flat. I ended up just embracing the bumps on the underlying stone, which suits a classic

I replastered my daughter's room and you're right, I could never get it flat. I ended up just embracing the bumps on the underlying stone, which suits a classic cottage anyway. Looking at fibre cement cladding for the exterior on an extension for just the reasons you say- plastering is an art and easy to screw up (cracks show up for one thing). similarly I'd use a mason for block walls, if we were doing blocks.