Dwelling structure looks at the type of dwelling for all occupied private dwellings. In 2001 and 2006, this was classified according to responses on the form by the household, while in 1996, it was classified by the Census collector. The categories are broadly based on the density and height of the housing types.

'Separate house' includes all free-standing dwellings not physically joined to any other.

'Medium Density' in 2006 includes 'Two or More Flats/Units/Townhouses/Apartments/Houses joined together in a one storey, two or three storey building', as well as the same category with no storey information. These categories include all dwellings joined to at least one other. In 2001 and 1996, this category includes all flats/units or townhouses joined together in a 1 or 2 storey building, but does not include 3 storey buildings. It also includes flats attached to shops or businesses.

'High density' in 2006 includes all dwellings joined together in a four or more storey block. In 2001 and 1996 it includes three storey buildings and higher. As a result of this definitional change, care should be taken when looking at the medium and high density categories separately over time, particularly where medium-sized apartment blocks are known to exist.

'Other dwelling' includes caravans, mobile homes, improvised dwellings or shelters and people sleeping rough.

Unoccupied dwellings are shown separately in the table, broken down by the reason for unoccupancy. This was a separate question on the form, answered by the Census collector. Further information on this classification is on the Statistics New Zealand website.