A:Answer There should be no obstacles, such as a fence or wall, within 20” from the back of the cabinet because it will prevent heat radiation of the condenser. This unit is designed for installation in standard double-hung windows with an actual opening width from 22” to 36”. The top and bottom window sashes must open sufficiently to allow a clear vertical opening of 13” from the bottom of the upper sash to the window sill. Please visit https://www.lg.com/us/wall-air-conditioners to browse available options of through the wall units. See the specifications to confirm that the unit meets your specific needs. ^Daphane