Tenn. Code Ann. § 4-6-114

The commissioner vested with the administration of the institutions named in § 4-6-102 may employ an architect or architects skilled in methods of sanitation and the preparations of plans, specifications, estimates and details for buildings, betterments and such items of equipment as may be required in any of those institutions, and also employ such mechanical engineers, superintendents and supervisors as the commissioner may deem necessary, and fix their titles and compensations, which, with all necessary expenses, when itemized and approved, shall be paid like other expenses of the department.