(1) The powers and duties of any landmark heritage preservation commission created pursuant to sections 14-2001 to 14-2004 shall be such as are delegated or assigned by the ordinance establishing the landmark heritage preservation commission. The city council shall specifically state in such ordinance which powers the landmark heritage preservation commission shall be allowed to exercise.

(2) The powers of a landmark heritage preservation commission shall not be repugnant to any other provision of law and shall be exercised only in the manner prescribed by the ordinance. No action of the landmark heritage preservation commission shall contravene any provision of a zoning or planning ordinance unless such action is expressly authorized by the city council.