The narrator, which provides the point of view for "A Rose for Emily," is the town of Jefferson, a collective entity that seems to be able to recount Miss Emily's life over the span of decades. This third-party limited narrator, although it has a long memory of Miss Emily's life, can only recount what it sees and hears, like a continually rolling video camera. Because the narrator has no knowledge of Miss Emily's inner self, it cannot report on her inner feelings, her beliefs, her private actions. It can therefore only report public events in Miss Emily's life.
These public events--the meeting with the aldermen over taxes; the purchasing of poison; carriage rides with Homer Barron--by their nature are episodic, that is, they happen over time but are not told in a sequential manner. For example, the story begins with the death of Miss Emily, which leads the narrator to recount the confrontation with the town about Miss Emily's failure to pay taxes and then to the incident of the over-powering smell emanating from Miss Emily's house.
Typically, the town-narrator loses track of Miss Emily for years at a time because nothing happens to her that allows public scrutiny:
She was sick for a long time. When we saw her again, her hair was cut short, making her look like a girl. . . .
Following this comment, however, the narrator recounts the story of the "contracts for paving the sidewalks," and the advent of Homer Barron. Again, the Homer Barron episode obviously occurs sequentially in time, but the narrator recounts the Homer Barron episode after it has discussed the episode in which Emily buys arsenic--ostensibly, "for rats"--and the poison purchase is told after the episode in which the town takes care of the horrible smell around Miss Emily's house. In effect, we get important parts of the overall story in reverse order, which helps to leave the reader slightly confused about how the episodes work together to lead to a conclusion.
The melding of a third-party limited narrator--limited to what it can see and hear--and the episodic nature of the narrative help to create the somewhat dis-jointed experience in the reader's attempt to understand where these episodes finally lead. And this dis-jointed series of events keep the reader from forming a linear view of Miss Emily's story so that, at the end, the room behind the locked door has its horrific effect.