An extendable deck device is disclosed that creates additional room for homes with limited outdoor space. The extendable deck device comprises a plurality of squares, with each square comprising a frame and a plurality of support beams secured thereto, and a floor component positioned on top of the plurality of squares to substantially cover the plurality of squares. The extendable deck device further comprises at least one rail component secured to a perimeter edge of the floor component, which protrudes vertically upwards from the floor component. The rail components can be extended or retracted either manually or via an electric motor and reel. Further, the deck device can comprise at least one set of stairs secured underneath a corner of the floor component. The stairs can be secured to the corner, such that a user manually extends out the stairs from underneath the floor component for use.