Okla. Stat. tit. 63 § 1084
Notwithstanding any other provisions of law, or of any municipal or county ordinance or local building code, the standards for factory-built housing, housing prototypes, subsystems, materials and components certified as acceptable by the Federal Department of Housing and Urban Development are hereby deemed acceptable and approved for use in housing construction in this state. A certificate from the State Director of the Federal Housing Administration of the Department of Housing and Urban Development shall constitute prima facie evidence that the products or materials listed therein are acceptable and such certificates shall be furnished by the building contractor to any local building inspector or other local housing authority upon request. The provisions of this act will not preclude on-site inspections by cities and towns of the service connections for electrical and sanitary facilities.
Okla. Stat. tit. 63, § 1084