There were 5460 unoccupied private dwellings across the Wollongong local government area on census night last August despite the housing crisis gripping the region.

There could be a number of reasons for that - including the house being a holiday home or a vacant investment property, or new apartments in a high rise building that had yet to be made available for rent, according to the Housing Trust's CEO Michele Adair.

Read more: Wollongong mum, three kids move into caravan park amid housing crisis

Ms Adair said the number of vacant buildings in the region is "gut-wrenching" when there are families sleeping rough in tents.

"It's absolutely gut-wrenching ... because the the burden of this crisis is growing week after week," Ms Adair said.

"Even if 10 per cent of those homes were made available, that would be another 500 families who had safe secure housing, which is a fundamental human right.

"We have less than 0.5 vacancy rate of rental properties in the Illawarra. And that is beyond crisis point."

Read more: Wollongong family of four living in tents for past two years

There are around 3500 Illawarra residents on the social housing waitlist, which has an expected wait time of five to 10 years, according to data from NSW Family and Community Services.

Ms Adair said an audit of vacant Illawarra properties must be undertaken to determine where the empty properties lie, whether they need maintenance, and whether they could become available for rent.

"We have to find out where they are, and if a home is beyond its useful life and in need of massive amounts of maintenance to bring it up to a liveable standard," she said.

Ms Adair added that policy changes were needed to discourage properties from being left vacant as the crisis deepens.

"In a growing number of jurisdictions, including in Melbourne, there has been very considered thought to a vacancy tax ... where if a property is sitting vacant for some months, then the owner of that property is actually charged for keeping that property vacant."

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