No building shall hereafter be erected, nor shall any existing building be moved, structurally altered, rebuilt, added to or enlarged, nor shall any land be designed or used for any purpose other than those included among the uses listed as permitted uses in each zone by this chapter and meeting the requirements set forth in the schedule made a part of this chapter.[1] Nor shall any open space contiguous to any building be encroached upon or reduced in any manner except in conformity with the yard, lot area, building location, percentage of lot coverage, off-street parking requirements, and such other regulations designated in said schedule and in this chapter for the zone district in which such building or space is located. In the event of any such unlawful encroachment or reduction, such building shall be deemed to be in violation of this chapter, and the certificate of occupancy shall become void. No building permit shall be issued unless and until all requirements of §§ 540-12 and 540-20 have been complied with.