Okla. Stat. tit. 19 § 863.18
After the adoption of such zoning regulations or building line regulations by the board and/or the council, no building or other structures shall be erected, constructed, enlarged or altered, or repaired in such manner as to prolong the life of the building, nor shall the use of any land be changed without a permit issued by the county inspector as to territory falling within the jurisdiction of the county and of the building inspector of the municipality as to territory falling within the jurisdiction of the municipality. The county inspector shall have the duty of administering the rules and regulations under this act applicable to the unincorporated area of the county, and shall make such inspections and investigations as may be necessary to the proper enforcement of such rules and regulations. The building inspector and the engineer of the municipality shall have the duty of administering the rules and regulations under this act applicable to the jurisdiction of the municipality and shall make such inspections and investigations as may be necessary to the proper enforcement of such rules and regulations, except that in the matter of construction, surfacing and maintenance of streets, roads, and highways in the entire unincorporated area of the county, the board may prescribe rules and regulations and prescribe standards and the county engineer shall have the duty of administering such rules and regulations and shall make such inspections and investigations as may be necessary to the proper enforcement of such rules and regulations.
Okla. Stat. tit. 19, § 863.18