Supplementary rental supply? The digital market for low-cost and informal housing in Sydney, Australia

This article examines real estate platforms and the data they generate to provide new insights into housing markets and practices, focusing on lower-cost and informal sectors, where building or rental regulations are often bypassed or contravened. We examine online listings advertised in Sydney, one of the most expensive cities in Australia and the world, compiling data from four dominant platforms - Realestate.com.au, Flatmates.com.au, Gumtree.com.au and Airbnb.com - each of which offers a particular type of rental accommodation. Using these datasets, we identify a typology of lower-cost and informal tenures and dwelling units, ranging from secondary dwellings and illegally subdivided apartments to shared accommodation and precarious rental agreements. Our study highlights a supplementary supply of rental housing, operating within the conventional private rental market, accessed and made visible via the platforms we examine. Applying a statistical regression approach, we examine relationships between concentrations of informal housing supply and socio-economic variables. The findings reveal intersections between digital platforms and evolving informal market practices and have implications for urban planning and housing policy.