Are plaster walls expensive?

If you live in a house built before 1940 and the walls haven't been updated, they're most likely made of plaster. If you've also thought about building new walls or adding them to your current home, one of the decisions you'll have to make is how you want those walls to be finished. One of the best things about plaster walls is the ability to add designs and textures, creating unique and interesting walls. The builders nailed thin, closely spaced strips of wood (slats) to the wall studs and then smoothed multiple layers of plaster onto the mesh to form flat wall surfaces.