In this subchapter:
(1) "Building" means any enclosed structure designed for use as a habitation or for a commercial use, including engaging in trade or manufacture.
(2) "Owner" means the person that owns the real property on which a building is situated, according to:
(A) the real property records of the county in which the property is located; or
(B) the records of the appraisal district in which the property is located.
(3) "Unit" means an enclosed area designed:
(A) for habitation by a single family; or
(B) for a commercial use, including engaging in trade or manufacture, by a tenant.