(a) General rule.--In the case of a sale of a cooperative interest where delivery of a public offering statement is required, a contract of sale may be executed, but no interest in that cooperative interest may be conveyed until the declaration is recorded and unless all structural components and common element mechanical systems of the structure containing or constituting such unit or units and the common elements appurtenant thereto are substantially completed in accordance with the descriptions set forth in both the declaration pursuant to section 4205 (relating to contents of declaration) and in the public offering statement pursuant to section 4403 (relating to public offering statement; general provisions). Such substantial completion shall be evidenced by a recorded certification of completion executed by an independent registered surveyor, architect or professional engineer with regard to any such structure.

(b) Sale prior to completion of unit.--Nothing contained in this subpart shall prevent the offering for sale of a cooperative interest or the execution of any agreement to sell and purchase a cooperative interest or any interest in a cooperative interest, as opposed to actual conveyance, prior to the completion of the unit or any other portion of the cooperative.