Ohio Rev. Code Ann. § 749.27

All contracts mentioned in section 749.26 of the Revised Code shall be made in the name of the board of hospital trustees, and it shall be stipulated therein that the contractors will not execute any extra work or make any modifications or alterations in the specifications and plans, unless ordered in writing by the board, that they will not claim pay therefor unless such written order is given, and the additional compensation fixed and agreed upon. Copies of the plans and drawings, attested by the contractor, and the original bids, specifications, and contracts shall be deposited in the office of the clerk of the municipal corporation.