Abstract: An extendable room comprises accordion type ceiling and wall panels which fold within panel covers when the room is retracted, thereby taking up much less interior space and leaving the interior of the primary structure just as attractive, albeit smaller, as prior to retraction. The wall and ceiling panels are hinged together with tongue and groove connections and are secured in the flat, extended configuration by steel cables running through the panels. The side walls also include windows which may be made clear and opaque electronically. The secondary floor is retractable below the floor of the primary structure when the room is retracted, permitting the room extension floor to become the primary floor.