The Flynn-Fletcher house is an adequately sized house on the residential road known as Maple Drive. It is decorated externally with yellow and brown as its main colors.
- Entrance: The front entrance is at the end of a long set of steps through the front yard.
- Living Room: A yellow couch, a coffee table, and a television set are the most prominent furnishings of this room. There is a video game console plugged into the TV, which Candace has once been seen playing a robot wrestling-themed game with Stacy ("Tree to Get Ready") and another time by Phineas and friends ("She's the Mayor"). There is a glass screen door behind the sofa leading to the backyard and a fireplace on another side of the room.
- Kitchen: This room is where the family would gather for their regular meals. The kitchen is furnished with a refrigerator and lined on three sides with a counter. The room is stocked with an oven and a sink as any kitchen is. On another side of the room is the family dining room which has a dining table. The kitchen can be accessed directly from either the living room or the garage.
- Backyard: All grass and a tree in the middle of the lawn. A vast majority of Phineas and Ferb's big ideas take shape here.
- Garage: The family car is usually kept in here when it isn't being used. There is a washer-dryer system. ("Doofapus")
- Front room: In the front room there is a green sofa, a camel-shaped lamp, and a fireplace.
In the basement there is an entrance to a 'panic room' in which Candace would seek refuge during times she is overwhelmed by hysteria on matters involving her brothers. On the wall is a frame with "The Panic Room" written in it. The room is stocked with Candace's worn-out teddy bear, Mr. Miggins. ("I, Brobot", "Invasion of the Ferb Snatchers")
- Stairs: The stairs connect the first and second floor. It ends near Phineas and Ferb's room.
- Phineas and Ferb's Room: Phineas and Ferb share this bedroom on the second floor. Both have their own side of the room which is decorated in their favor. On Phineas' side which is on the left when viewed from the entrance is an inflatable raft-themed bed titled "S.S. Phineas" with an aquarium behind it. Other furnishings on his side of the room include a totem pole and a bean bag chair. On Ferb's side of the room is his own bed which is aligned with Phineas'. His side of the room is furnished with a nineteenth century phone booth, an Easter Island stone head and a bookshelf. Between Phineas and Ferb's bed is another smaller bookshelf that appears to have been converted from an old oil keg. Behind it is a window that most probably overlooks the front yard. The ceiling is decorated to look like the sky and has a yellow chandelier hanging from it. ("Just Passing Through") ("Phineas' Birthday Clip-O-Rama!") ("Phineas and Ferb The Movie: Across the 2nd Dimension")
- Candace's Room: Candace's room overlooks the backyard. It seems to have the same floor plan as her brothers' room but is furnished differently. It is decorated mostly in lavender and pink.
- Mom and Dad's Room: This is most presumably the home's master bedroom. Not much has been shown of it besides the bed. Hanging over either side of it is a reading lamp. On one side of the room is a drawer with several objects, including an alarm clock, while On the other side is a book shelf. A number of picture frames decorate the room's brown walls. ("Phineas and Ferb Summer Belongs to You!")
Most of the Flynn-Fletchers' immediate neighbors remain unseen. Their nearest and most notable neighbors include Vivian with her daughter Isabella across the street, Mrs. Weaver, who has only been given a mention ("Thaddeus and Thor"), and a woman named Peggy McGee who saw all of the boys inventions ("Thanks But No Thanks").
Other people known by the Flynn-Fletchers, including the Van Stomm and Hirano families aren't immediate neighbors but appear to be within a reasonable walking distance. Jeremy and the rest of his family appear to live the furthest away. ("One Good Scare Ought to Do It!")
- It was confirmed by Dan Povenmire that the house's address is 2308 Maple Drive. That address also appeared on a package for Perry. ("The Doonkelberry Imperative")
- In some episodes, the side of the house where there is a branched off section is cut out, with only a flat wall visible in its place.
- Most of Phineas and Ferb's big ideas take shape in the backyard. It is clearly a very large yard, but its size varies according to how much room the boys need to build their Big Idea for the day. The tree is a constant feature, as is the fence and the gate opening to the driveway.
- In the episode Lawn Gnome Beach Party of Terror, the boys build a beach in the backyard in the area behind the fence. This contradicts the bird's eye shots in other episodes that indicated the presence of another house in that area.
- In Rollercoaster, an explosion cut away half of the oak tree in the backyard. However, the oak tree is in perfect condition in the next episode.
- When the boys built big ideas, the house seems to increase in size, while when their projects are smaller in scale, the house would shrink.
- In "No More Bunny Business", Dennis the Rabbit can be seen looking at a blueprint for the house's floor plan. However, the house's actual floor plan remains unclear.
- In some episodes, a staircase is seen from the living room but in most episodes, it's not.
- In an incident with one of Phineas and Ferb's big ideas, the house suffered massive damage. However, this was only in a dream. ("Phineas and Ferb Get Busted!")
- The house is evidently located directly beneath a major air corridor. Passing aircraft have interfered with Phineas and Ferb's projects at least twice. ("Phineas and Ferb Summer Belongs to You!", "The Great Indoors")
- Sometimes the backyard can be larger than usual.
- In many of the early episodes, the small door led to the living room, later it led to the kitchen.
- The path that leads to the small door changes from a solid asphalt path to a stone path to no path at all from episode to episode.