No building or structure shall hereafter be erected, moved, structurally altered, rebuilt or enlarged except as provided herein nor shall any land be used for any purpose other than those allowable in each zoning district as designated herein (i.e., any use not enumerated in the applicable zone as a permitted use, a conditional use in which all specific standards are met or as an allowable accessory use associated with a permitted use shall be prohibited); nor shall open space contiguous to any building be reduced in any way except to conform to the provisions of this article and this chapter.