Ohio Rev. Code § 2305.31
A covenant, promise, agreement, or understanding in, or in connection with or collateral to, a contract or agreement relative to the design, planning, construction, alteration, repair, or maintenance of a building, structure, highway, road, appurtenance, and appliance, including moving, demolition, and excavating connected therewith, pursuant to which contract or agreement the promisee, or its independent contractors, agents or employees has hired the promisor to perform work, purporting to indemnify the promisee, its independent contractors, agents, employees, or indemnitees against liability for damages arising out of bodily injury to persons or damage to property initiated or proximately caused by or resulting from the negligence of the promisee, its independent contractors, agents, employees, or indemnitees is against public policy and is void. Nothing in this section shall prohibit any person from purchasing insurance from an insurance company authorized to do business in the state of Ohio for his own protection or from purchasing a construction bond.
R.C. §2305.31