New houses being built 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 10-year period from calendar year 2012 to 2021. 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, 2012 to 2021' datacube located in the data downloads section of Building Approvals, April 2022.

Australians are building houses on smaller blocks: the average site area of new house approvals decreased considerably over the last 10 calendar years, by 64 square metres (-13%), whilst the average floor area decreased by only 3 square metres (-1%). Some states have seen a stabilisation in the decrease in average site area over the last two years.

The average site area of new houses in Australian capital cities has decreased by 13% (64 square metres) over the last ten years, from 496 square metres in 2012 to 432 square metres in 2021. The graph below shows that the rate of decline was steady over ten years.

Across the five largest states, average site areas for house approvals trended downwards in all capital cities over the past ten years, as shown in Graph 2, resulting in increased housing density across the capitals. Greater Brisbane decreased the most, by 112 square metres (-20%), from 571 square metres in 2012 to 459 square metres in 2021. Greater Adelaide decreased the least (-6%), by 30 square metres, from 498 square metres to 468 square metres over ten years.

Greater Perth had the smallest average site areas of the capital cities across the 10-year period, while either Greater Adelaide or Greater Brisbane had the largest for nine of the ten years, except in 2015 when Greater Melbourne had largest average site area.

The Greater Capital City areas of Sydney and Brisbane reached average site areas of less than 500 square metres for new houses by the 2014 calendar year, after which site areas trended lower through to 2019 in these cities, before showing signs of stability.

Based on 2021 results, there is evidence the downward trend in average site area in the COVID pandemic-era approvals has slowed.  Between 2019 and 2021, the average site area in Greater Melbourne and Greater Perth continued to fall (-4% and -1%, respectively), while Greater Sydney and Greater Adelaide saw rises over the same period (2% each).  In Greater Brisbane the average site area was unchanged from 2019 to 2021 (459 square metres). 

While the average site area of new house approvals decreased considerably over the last 10 years, the average floor area of new houses approved in Australian capital cities showed less overall change but greater volatility over that ten year period. In 2012, the average floor area was 245 square metres and in 2021 the average was 242 square metres, a decrease of three square metres (-1%) over 10 years.

The combined trends of smaller site areas and largely unchanged floor areas of house approvals over time shows that Australians are building similar sized houses with smaller yards. The ratio of floor-to-site area increased between 2012 to 2021, from 0.49 to 0.56, driven by greater densification. This reflects a combination of factors, including increases in land cost, a greater proportion of new houses being constructed in urban infill locations, and more two-storey houses that maximise living space on smaller lots. 

Greater Sydney was the capital city with the largest average floor area for newly approved houses throughout most of the 10-year period, declining slowly from 271 to 254 square metres, while Greater Adelaide generally had the smallest (growing slowly from 209 to 220 square metres), as shown below. Greater Melbourne had the largest average floor area for newly approved houses in 2019 and 2020.

In the last two years, Greater Perth had the smallest average house sizes, of 215 and 214 square metres, respectively.

The Greater Capital Cities of Brisbane (+5%) and Adelaide (+5%) increased in average floor areas from 2012 to 2021, while Greater Sydney and Greater Perth both decreased at the same rate (-7%) over this period. Greater Melbourne average floor areas were stable with results of 247 in both 2012 and in 2021, ranging from 244 to 259 over 10 years.

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, 2021

Data are presented for Greater Capital City Statistical Areas. For further information, see Australian Statistical Geography Standard (ASGS): Volume 3 - Main Structure and Greater Capital City Statistical Areas

Building Approvals unit records with either no floor area or no site area data have been excluded from the analysis. Records that meet any of the following criteria have also been excluded: 

• floor area less than 100 square metres or greater than 750 square metres;
• site area less than 200 square metres or greater than 1000 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.

09/06/2022 - Updated commentary relating to the average site area for Greater Brisbane from 2019 to 2021.