Ohio Rev. Code § 6117.27
After the issuance and sale of bonds or certificates of indebtedness, as provided in sections 6117.01 to 6117.45, inclusive, of the Revised Code, the board of county commissioners shall enter into a written contract in accordance with sections 307.86 to 307.92, inclusive, of the Revised Code. The contract shall be between the board and the bidder, and the board shall pay the contract price in cash. Such payment may be made in proper installments as the work progresses. When there is reason to believe that there is collusion or combination among the bidders, the bids of those concerned therein shall be rejected. Whenever it becomes necessary, in the opinion of such board, in the prosecution of any such work or improvements, to make alterations or modifications in such contract, such alterations or modifications shall only be made by such board by resolution. Such resolution shall be of no effect until the prices to be paid for work or material, or both, caused by such alterations or modifications, have been agreed upon in writing and signed by the contractor and said board. No contractor for any such work shall recover anything for additional work or materials required by any alterations or modifications or for any other cause due to such alterations or modifications, unless such contract is made as provided in this section, nor shall he in any event recover for such work or materials or other cause more than the agreed price. The money derived from the lawfully authorized bonds or certificates of indebtedness sold as provided in section 6117.25 of the Revised Code, shall not thereafter be considered unappropriated until the county is fully discharged from such contract.
R.C. § 6117.27