Tenn. Code Ann. § 71-5-2206

When money is to be drawn from the county treasury for the purchase of the site of the asylum, the erection of the buildings, for improvements, repairs, or for the ordinary expenses of the maintenance of the poor, it shall be done upon an order of the commission, entered upon its minutes, specifying the purpose to which the money is to be applied; upon production of a copy of which, signed by the county mayor and attested by one (1) of the other commissioners, to the county legislative body, and appropriation shall on approval be made for the amount specified in the order, to be drawn on warrant of the county mayor, as in other cases.