Mo. Rev. Stat. § 448.4-120: Substantial completion of units.

In the case of a sale of a unit where delivery of an original sale certificate is required, a contract of sale may be executed, but no interest in that unit may be conveyed until the declaration is recorded and the unit is substantially completed, as evidenced by a recorded certificate of substantial completion executed by a registered and licensed architect or engineer, or by issuance of a certificate of occupancy authorized by law.