No person proposing a subdivision, plat or P.U.D. shall sell, agree to sell, transfer, lease or otherwise convey any lot, parcel or tract in a subdivision, or construct or commence the construction of any building or structure in a subdivision until the secondary (final) plat of the proposed subdivision is approved by the Plan Commission and recorded in accordance with provisions hereof.

No person proposing a subdivision, plat or P.U.D. shall proceed with any grading and improvements for streets or installation of public utilities until the primary (preliminary) plat of the proposed subdivision is approved by the Plan Commission.