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Dwelling structure (STRD)

Census of Population and Housing: Census dictionary
Reference period


This variable records the structure of private dwellings.


Private dwellings



Separate house


Separate house

Semi-detached, row or terrace house, townhouse etc. with one, two or more storeys


One storey


Two or more storeys

Flat or apartment


In a one or two storey block


In a three storey block


In a four to eight storey block


In a nine or more storey block


Attached to a house

Other dwelling




Cabin, houseboat


Improvised home, tent, sleepers out


House or flat attached to a shop, office, etc.

Supplementary Codes


Not stated


Not applicable

Number of categories:  14

Not applicable (@@) category comprises:

  • Non-private dwellings
  • Migratory, off-shore and shipping SA1

Category definitions

Separate house
  • Is structurally independent from surrounding dwellings.
  • May have a flat attached to it, such as a granny flat or converted garage (the flat is categorised under Flat or apartment - see below).
  • The number of storeys of separate houses is not recorded.
  • Dwellings in manufactured home estate.
Semi-detached, row or terrace house, townhouse, etc. with one, two or more storeys
  • Have their own private grounds.
  • No other dwelling above or below them.
  • They are attached in some structural way to one or more neighbouring dwellings.
Flat or apartment
  • Dwellings in blocks of flats or apartments.
  • Do not have their own private grounds.
  • Usually share a common entrance foyer or stairwell.
  • Flats attached to houses such as granny flats, and houses converted into two or more flats.
  • Includes all occupied caravans, regardless of where they are located. Occupied campervans are also included. For further detailed information see Caravans in this glossary.
Cabins and houseboats
  • This includes all occupied cabins and houseboats.
  • Cabins are self-contained and not intended for long-term residential use. This includes occupied cabins located in residential parks or set up as temporary accommodation.
  • A houseboat is an occupied mobile dwelling (intended for use on water). It is not typically intended for long-term use, although it could be currently used on a permanent or semi-permanent basis.
  • Occupied houseboats are treated as occupied private dwellings regardless of location.
  • Separate houses in caravan or residential parks or marinas occupied by managers or caretakers are not included in this category.
Improvised home, tent, sleepers-out
  • These include sheds, tents, humpies and other improvised dwellings that were occupied on Census night.
  • This category includes people sleeping-out, including those sleeping on the streets, in abandoned buildings, under bridges or in cars.
House or flat attached to a shop, office, etc.
  • A house or flat attached to a shop, office, factory or any other non-residential structure is included in this category.

Question(s) from the Census form

This variable is not collected from a question on the Census form.

How this variable is created

Initially, this data is sourced from the ABS Address Register. For more details, refer to the ABS Address Register, Users' Guide.

In some cases the Dwelling structure is updated after information is returned from ABS field officers during their visits to dwellings.

New dwellings added by Census staff either have their Dwelling structure added by the field officer or imputed from the surrounding dwellings during processing.

Depending on Dwelling structure type and the method by which the Address Register is updated, the dwelling’s STRD is derived by relying on the information provided by Census field officers and the Address Register, with Building Approvals data also assisting in some cases. STRD for Non-private dwellings (NPDs) is set to ‘not applicable’, and for Private Dwellings, the below table shows the derivation source.

If dwelling structure data is:
Field OfficerAddress RegisterSTRD derived from






Address Register



Field Officer



Field Officer*

*Building Approvals data used in some cases

Certain types of dwelling structures, such as 'Improvised homes, tent, sleepers-out' are given particular attention during data processing to quality assure the homeless population.

History and changes

Some information on the structure of Private dwellings has been collected for all Censuses since 1911, though the specific types of classification used have varied significantly.

Cabins and Houseboats

Prior to the 1986 Census, occupied craft in marinas were treated as Non-private dwellings, however occupied houseboats and occupied small boats are now treated as Occupied private dwellings.

Collection methods before 2016

From 1976 to 2011, the information on Dwelling structure was collected by Census Field Officers in the Collector Record Book at the time the Census forms were delivered instead of being on the Census form.

In 2016 there was a change in the way the data was collected. It was initially recorded by ABS Address Canvassing Officers in the lead up to the Census, as part of establishing the Address Register as a mail-out frame for designated areas (93% of Australian addresses). In areas enumerated using the traditional approach of delivering forms, the information was collected by ABS Field Officers during the Census collection period. Location of private dwelling data was also updated as required by ABS Field Officers during the Census enumeration period. Dwellings in remote areas continue to have their structure collected solely by field officers.

In 2021, the Address Register is considered the main source of Dwelling location data, and real-world frame amendments are made when appropriate, by Field and Office staff.


For the 2016 Census, there was a change to one of the response categories for this variable. The previous category of 'Caravan, cabin or houseboat' has been separated into two categories:

  • 'Caravan'
  • 'Cabin, houseboat'

There has been further disaggregation of the flat/apartment categories to align with different building rules in place for buildings with a height greater than 25 metres and to meet increasing stakeholder demand for more data about high rise apartment buildings. The previous category ‘In a four or more storey block’ is separated into two categories:

  • ‘In a four to eight storey block’
  • ‘In a nine or more storey block’
Separate house and semi-detached definitions

For the 2021 Census, there is a change to the half a metre rule that had previously distinguished separate houses from semi-detached dwellings. The new definition is purely structural in which a separate house (constructed in the last 20 years) must be structurally independent, regardless of separation from adjacent dwellings. This change is expected to reduce subjective interpretation by Census Field Officers and align with the way structure data is provided for the Building Approvals collection. (More details here).

Missing dwelling structure

For the 2021 Census, addresses that don’t have Dwelling structure recorded from observation or administrative data sources will have the information populated by an imputation model.

Data use considerations

Data on Dwelling structure is used to monitor changes in housing characteristics, to help formulate housing policies and to review existing housing stock.

Minor inconsistencies in Dwelling structure counts may exist between Censuses due to subjective interpretation of structural definitions between individual Field Officers.

Although a review has been conducted to update Dwelling structure in light of changes to the half a metre rule for buildings constructed in the last 20 years, some older dwellings may still reflect the old definition.

The Address Register uses an imputation process to impute Dwelling structure for a small number of dwellings that do not have structure defined. This should mean the number of 'not stated' may be smaller than last Census.

Related variables and glossary terms

Other ABS sources