Australia's private rental market is currently experiencing a shortage of affordable properties, according to the latest study by the Australian Housing and Urban Research Institute (AHURI).

While the private rental sector is expanding strongly at more than twice the rate of household growth, options for low and very-low-income households remain thin.

In fact, there is a shortage of 305,000 affordable and available rental properties for very-low-income households between 2011 and 2016. This shortage has been increasing over the recent years, said lead researcher Professor Kath Hulse from Swinburne University.

"What we found is strong evidence of what appears to be structural rather than cyclical change in the private rental sector. Over this period, there was an increase in privately rented dwellings with mid-market rents that were only affordable to middle and higher-income households, as well as an increase in the proportion of these households in the private rental market," she said.

This has left a limited supply of housing for very-low-income households, with up to 80% living in unaffordable rentals across the country.

"The challenge is to develop policies and settings that can lead to a greater supply of lower-rent housing. This challenge has become more urgent in view of our findings," Hulse said.

There was also a shortage of 173,000 affordable and available rental properties for low-income households across Australia. Furthermore, about 43% of affordable homes for this group are being occupied by middle and higher-income households.

Of the capital cities, Sydney has the most alarming unaffordability.

"The absolute shortage of dwellings affordable for low-income households in Sydney between 2011 and 2016 is a remarkable change. Customised policy development is required to boost affordable rental supply for low-income households in Sydney so they can continue to work in jobs necessary for the effective running of an international city such as Sydney," Hulse said.