Indiana Code Title 36. Local Government § 36-1-12-18

Sec. 18. (a) If, in the course of the construction, reconstruction, or repair of a public work project, it becomes necessary to change or alter the original specifications, a change order may be issued to add, delete, or change an item or items in the original contract.  The change order becomes an addendum to the contract and must be approved and signed by the board and the contractor.

(b) If a licensed architect or engineer is assigned to the public work project, the change order must be prepared by that person.

(c) A change order may not be issued before commencement of the actual construction, reconstruction, or repairs except in the case of an emergency.  In that case, the board must make a declaration, and the board's minutes must show the nature of the emergency.

(d) The total of all change orders issued that increase the scope of the project may not exceed twenty percent (20%) of the amount of the original contract.  A change order issued as a result of circumstances that could not have been reasonably foreseen does not increase the scope of the project.

(e) All change orders must be directly related to the original public work project.

(f) If additional units of materials included in the original contract are needed, the cost of these units in the change order must be the same as those shown in the original contract.