Myth busted: Australia’s houses are not the world’s largest

CommSec has released its annual Home Size Trends Report, which claims that Australia’s houses are now the world’s largest:

Australia is again building the biggest houses in the world. Data commissioned by CommSec from the Australian Bureau of Statistics, shows the average new house built in 2019/20 was 235.8 square metres, up 2.9 per cent on the year and the biggest increase in 11 years.

US houses built over 2019 (latest data) fell for the fourth year, down 3 per cent to 2,509 square feet (the equivalent of 233.1 square metres).

Not only have Australian houses grown over the past year, so has the size of the average Australian apartment. The size of the average new apartment lifted 6 percent over the past year, hitting a decade high of 136.8 square metres.

Overall, the average new home (houses and apartments) built in 2019/20 was 195.8 square metres, up by 3 per cent over the year to a 6-year high.

While Australia is again building the biggest houses in the world, US homes (houses and apartments) are slightly bigger than in Australia: 197.4 square metres versus 195.8 square metres in Australia…

Apart from Australia and the US, Statistics New Zealand regularly calculates the average floor area of a new dwelling. The Canadian Home Builders Association has also advised data on home size (based on Ontario and 2016 Census data)…

In Canada the average size of a new house (detached dwelling) was 221.1m² and the average new home was 141.2m².

In 2012, Eurostat compiled data on the “Average size of dwelling by income quintile and tenure status”. The data ranged from 43.9m² in Romania to 141.2 m² in Cyprus.

CommSec’s analysis needs to be taken with a huge pinch of salt.

First, the ABS measures floor area for houses as:

…the quantity of useable space within the dwelling (including attachments) at its completion. This figure is measured in meters squared (m²) as reported by the respondent at the final stage of construction. 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.

Since the early-1990s, there has been an increasing trend towards attached garages (see example below), whereas previously most new houses built car ports instead.

Under the ABS’ definition, such attached garages would be included as floor space, whereas car ports are not. Accordingly, Australian home sizes have been biased upwards, giving the impression that we have super-sized our homes, even though actual living space has likely risen more modestly (if at all).

It is also worth pointing out that the United States does not include attached garages in its floor area measurements, which further biases the results. Here’s the definition of floor area used by the US Census Bureau for detached houses [my emphasis]:

Single-family – For these statistics, floor area is defined as all completely finished floor space, including space in basements and attics with finished walls, floors, and ceilings. This does not include a garage, carport, porch, unfinished attic or utility room, or any unfinished area of the basement…

Myth busted.