BCA Class 1A - Class 1A building is a single dwelling being a detached house; or one of a group of attached dwellings being a town house, row house or the like.
BCA Class 2 - Class 2 buildings are apartment buildings. They are typically multi-unit residential buildings where people live above and below each other
BCA Class 4 - Class 4 are apart of a building is a sole dwelling or residence within a building of a non-residential nature