Australians building houses on smaller blocks

This article presents data on floor area and site area for new private sector houses approved in Australia's five largest capital cities across a 15-year period from financial year 2005-06 to 2019-20. The data presented in this article are sourced from the Australian Bureau of Statistics' (ABS) monthly publication 'Building Approvals, Australia'. These data are available in the Building Approvals 'Average Floor and Site Area, 2005-2006 to 2019-2020' datacube located in the data downloads section of Building Approvals, July 2020.

Australians are building houses on smaller blocks: the average site area of new house approvals decreased considerably over the last 15 years, by 135 square meters (-22%), whilst the average floor area increased by only 14 square meters (+6%).

The average site area of new houses in Australian capital cities has decreased by 22% (135 square metres) over the last 15 years, from 602 square metres in 2005-06 to 467 square metres in 2019-20. Graph 1 shows that the rate of decline was fairly steady over the 15 years.

Across the five largest states, average site areas for house approvals trended downwards in all capital cities over the past 15 years, as shown in Graph 2, resulting in increased housing density across the capitals. Greater Sydney declined the most, by 207 square metres (-32%), from 654 square metres in 2005-06 to 447 square metres in 2019-20. Greater Adelaide declined the least (-16%), by 103 square metres, from 634 square metres to 531 square metres over the 15-year period.

Greater Perth had the smallest average block sizes of the capital cities across the 15-year period, while Greater Adelaide had the largest from 2012-13 to 2019-20.

The Greater Capital City areas of Sydney, Melbourne and Brisbane all reached average site areas of less than 500 square metres for new houses by the 2017-18 financial year, after which site areas decreased annually through to 2019-20 in Greater Sydney and Greater Melbourne. In Greater Perth, the average site area has been less than 500 square metres each year since 2011-12, and has been below 450 square metres for the past seven financial years.
 

While the average site area of new house approvals decreased considerably over the last 15 years, the average floor area of new houses approved in Australian capital cities showed less change. In 2005-06, the average floor area was 234 square metres and in 2019-20 the average was 248 square metres, an increase of 14 square meters (+6%) over 15 years.

The combined trends of smaller block sizes and larger floor areas of house approvals over time shows that Australians are building larger houses with smaller yards. This reflects the rising cost of land, and a greater proportion of new houses being constructed in urban infill locations. More two-storey houses are also being constructed to maximise living space on smaller lots, particularly in greenfield developments. 

Greater Sydney was the capital city with the largest average floor area for newly approved houses throughout most of the 15-year period, declining slowly from 280 to 252 square metres, while Greater Adelaide generally had the smallest (growing slowly from 208 to 223 square metres), as shown in Graph 4. Floor areas for house approvals in Greater Sydney were larger than any other capital city until 2018-19, when Greater Melbourne overtook in the two most recent financial years.

The Greater Capital Cities of Brisbane (+18%), Melbourne (+10%), and Adelaide (+7%) increased in average floor areas in the 15 years to 2019-20, while Greater Sydney and Greater Perth declined 10% and 9% respectively.

The floor area of a house is defined as the expected quantity of useable space within the dwelling (including attachments) at its completion. This figure is measured in metres squared (m²) as reported by the council or private certifier on the building approval record. The boundary of the recorded floor area of a dwelling is delineated by the external perimeter of the dwelling's exterior walls. This excludes non-enclosed structures attached outside the floor area boundary such as verandahs and carports.

The site area of a house approval is a measure of the site area of the block of land the house will be situated on and is measured in metres squared (m²). This is also known as the 'lot size' or 'block size'.

Data are presented for private sector houses - defined as detached buildings used for long-term residential purposes, consisting of only one dwelling unit and are not a result of alterations or additions to a pre-existing building. For further information, see Functional Classification of Buildings, 1999 (Revision 2011).

Data are presented for Greater Capital City Statistical Areas. For further information, see Australian Statistical Geography Standard (ASGS): Volume 1 - Main Structure and Greater Capital City Statistical Areas, July 2016.

The proportion of records with floor area data that was not stated has varied annually between 20% and 27% of all new private houses. The proportion of records with site area not stated has improved considerably over the years, from 44% missing site area data in 2005-06 to 16% in 2019-20. Records with no floor area or no site area data have been excluded from the analysis. Additionally, records that meet any of the following criteria have been excluded from the analysis: 

• floor area less than 100 square metres or greater than 750 square metres;
• site area less than 200 square metres or greater than 2000 square metres;
• houses with an approval value under $100,000;
• approvals consisting of more than one house;
• houses where the approval value per square metre is unrealistic, most likely because the floor area provided on the building approval record was inaccurate; and
• Hobart, Darwin and the Australian Capital Territory have been excluded due to data missingness and large variability in average floor area and site area.