We have lath and plaster ceilings throughout our 30s house and since having building work done, one of the ceilings has cracked in a couple of places. The ceiling wasn't actually touched during building works so I presume it's from movement. I know the previous owner had recently skimmed over the ceiling but ids at it was more than just a hairline crack. Do lath and plaster ceilings stay up with cracks in them or am I going to get a nasty surprise on my head one day?