Class 1 buildings are houses. Typically, they are standalone single dwellings of a domestic or residential nature. These buildings can also be horizontally attached to other Class 1 buildings.
When attached they are commonly referred to as duplexes, terrace houses, row houses and townhouses. In these situations, they must be separated by a wall that has fire-resisting and sound insulation properties. The Class 1 classification includes two sub-classifications: Class 1a and Class 1b.
A 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.
A Class 1b building is a boarding house, guest house or hostel that has a floor area less than 300 m2 and ordinarily has less than 12 people living in it. It can also be four or more single dwellings located on one allotment which are used for short-term holiday accommodation.