The standard roof overhang is 8" for our structures. A roof has eaves, the edges of the roof, which overhang on the structure as they are longer than the side of the building. The eaves are then used to form an overhang on the structure to dispose of any water away from the siding, window, and doors and to provide extra shade to the windows. It is recommended that the overhang for the roof fits with the weather in your area.