Protecting plaster walls around shower surround?
My husband and I are young, first-time homeowners, and we just moved into a home that was built in 1928. The walls are plaster, and the bathroom has a standard shower surround with unprotected walls between the top of the surround and the ceiling. There is no existing water damage that we know of, but I assume plaster walls need to be protected from shower-related moisture just like drywall? If so, what is the best thing for us to do before we start taking showers in there? A waterproof membrane plus tile, or would something less extensive do the job?
I have researched similar topics in other threads, but the most common concern is existing damage. We just want to make sure the walls are protected against water, if they need to be. Thanks so much for any advice you can give!