Pursuant to T.C.A. § 13-7-101, a county may exercise zoning powers outside municipalties following adoption of a zoning ordinance and map.

The county legislative body is required to set up a county board of zoning appeals with three, five, seven, or nine members, except for counties with a population of less than 600,000 (1980 federal census or any subsequent census) adopting a charter form of government, which must establish a board of zoning appeals comprised of five, seven, or nine members. T.C.A. § 13-7-106. The board is to (1) "hear and decide appeals where it is alleged by the appellant that there is error in any order, requirement, decision or refusal made by the county building commissioner or any other administrative official in the carrying out or enforcement of any ordinance enacted pursuant to this part; (2) hear and decide, in accordance with the provisions of any such ordinance, requests for special exceptions or for interpretation of the map or for decisions upon other special questions upon which such board is authorized by any such ordinance to pass; and (3) where, by reason of exceptional narrowness, shallowness, or shape of a specific piece of property at the time of the enactment of the regulation or by reason of exceptional topographic conditions or other extraordinary and exceptional situation or condition of such piece of property, the strict application of any regulation enacted under such sections would result in peculiar and exceptional practical difficulties to or exceptional and undue hardship upon the owner of such property, authorize, upon an appeal relating to the property, a variance from such strict application so as to relieve such difficulties or hardship; provided, that such relief may be granted without substantial detriment to the public good and without substantially impairing the intent and purpose of the zone plan and zoning ordinances." T.C.A. § 13-7-109.