Ind. Code § 6-3.1-11-9

Sec. 9. As used in this chapter, "plant" means a building or complex of buildings used, or designed and constructed for use, in production, manufacturing, fabrication, assembly, processing, refining, finishing, or warehousing of tangible personal property, whether the tangible personal property is or was for sale to third parties or for use by the owner in the owner's business.