The following words and phrases whenever used in this article shall be construed as defined in this section:
(a) “parcel” shall mean a unit of real property as shown on the last equalized assessment roll of Los Angeles County,
(b) “improvement to property” shall mean a building or other improvement erected on or affixed to a parcel, and
(c) “building” shall mean any structure having a roof supported by columns or walls, for the housing, shelter or enclosure of persons, animals, chattels or property of any kind.