225 ILCS 440/3.08
"Erect" means to construct, build, raise, assemble, place, affix, attach, create, paint, draw or in any other way bring into being or establish; but does not include any of the foregoing activities when performed as an incident to the change of advertising message or normal maintenance or repair of a sign or sign structure. For the purposes of this definition, the following shall not constitute normal maintenance or repair of a sign or sign structure: replacing more than 60% of the uprights, in whole or in part, of a wooden sign structure; replacing more than 30% of the length above ground of each broken, bent, or twisted support of a metal sign structure; raising the height above ground of a sign or sign structure; making a sign bigger; adding lighting; or similar activities that substantially change a sign or make a sign more valuable.
225 ILCS 440/3.08