The hero of Other Voices, Other Rooms is a teenaged boy who finds himself in very difficult situations with some regularity. His mother's death; having to move in with his aunt and then again with his stepmother and her cousin; discovering that his father is paralyzed and unable to communicate with him—it's all enough to really send a person over the edge.
When Joel meets Little Sunshine and finds out about the Cloud Hotel, the title comes into focus. Little Sunshine the hermit lives at the abandoned hotel, saying that, "it was his rightful home […], for if he went away, as he had once upon a time, other voices, other rooms, voices lost and clouded, strummed his dreams" (1.5.27). Being uprooted from home opens a space for Little Sunshine to be invaded by other voices and rooms.
Just like Little Sunshine, Joel has left his home. He has been uprooted and a new place and new people have populated his world and imagination. He still has a way back, by using his imagination to go to his secret room (see Symbolism, Imagery, and Allegory) but the house that is his life has been remodeled to fit Skully's Landing.