For compound words, all of them can be used as a noun. They all mean "room", and I can't tell whether there is any rule to decide which one should be chosen. I guess most of native speakers just learn the whole compound word without thinking which one is more correct. For example: 房 examples: 書房= book + room = a study 廚房= kitchen/cook + room =kitchen 臥房= sleep + room = bedroom = 臥室= 寢室 室 臥室 寢室= sleep + room 浴室= bath + room = bath room 間 洗手間= hand-washing + room = toilet 停屍間= room for keeping corpses = Morgue

In general,“房”and“室”are used as a noun but“间”，Classifier . for example ，“一间房间”.besides ,most of the time,"房"refers to a whole house and "室"refers to a room."房间"can refer to a room too.