Removing plaster from walls can be a tricky business, especially if the plaster is older. Old plaster can be dried out and have a tendency to crumble when you take it from the walls. Here are some ideas that might help you avoid pulling down the rest of the house when you need to renovate your interior plaster walls.
Chipping Away at the Edges
If the whole wall is going to be re-plastered and you need to remove all of the existing covering it is a good idea to take a chisel and chip away about 2 inches from the edges of the wall. Much depends on what the plaster has been laid onto, as well. For example, if the plaster as has been laid over bricks and mortar you are less likely to cause damage to the underlying area. You can simply create a hole in the plaster and tap gently at it with a mortar chisel and rubber mallet to take bits away at a time.
Old and Dry
Old and dry plaster might have bits of the wall backing in it and could easily bring down a larger area of plaster and wall if you persist in removing it all at once. Take great care if you find any loose areas and try to remove them in small pieces, being careful of the wall underneath.