Mo. Rev. Stat. § 64.130: Regulations shall govern, when (first class counties).

Wherever the county zoning regulations made under authority of sections 64.010 to 64.160 require a greater width or size of yards, courts or other open spaces, or require a lower height of building or less number of stories, or require greater percentage of lot to be left unoccupied or require a lower density of population, or require a more restricted use of land, or impose other higher standards than are required in any other statute, local order or regulations, private deed restrictions or private covenants, the provisions of the regulations made under authority of sections 64.010 to 64.160 shall govern.