Iowa Code § 101.6: Ordinances by municipalities.

Rules promulgated pursuant to this chapter shall have uniform force and effect throughout the state and no municipality or political subdivision shall enact or enforce any ordinance or regulation inconsistent or not in keeping with the statewide rules. Provided that nothing in this chapter shall in any way impair the power of any municipality when authorized by other law to regulate the use of land by comprehensive zoning or to control the construction of buildings and structures under building codes or restricted fire district regulations. Provided, further, that the size, weight and cargo carried by vehicles used in the transportation or delivery of flammable liquids or liquefied petroleum gas shall be governed by the uniform provisions of the motor vehicle and highway traffic laws of this state and local ordinances therein authorized.