Trust CEO Michele Adair said the new space in Bridge Street would help the organisation grow, with plans to bring on new staff and double their portfolio of affordable rentals to 2400 by the year 2024.

"It's not just about big and high density, it's really about smart community appropriate redevelopment of what's already there," she said.

Ms Adair said ideally vacant land would be utilised to create more affordable rentals, however "green field sites" are often hard to come by.

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The trust is now looking outside the box to create housing, such as "uplift opportunities" and re-purposing old single dwelling homes currently owned by the NSW Government.

"Where there is say an older house built in the '50s that is needing an enormous amount of maintenance and repair - they're the sorts of opportunities where we'd like to ... redevelop that and pop up a duplex," Ms Adair said.

She said Wollongong was still in housing crisis for affordable rental properties, as "people need to rent before they'll be in a position to be able to buy".

"Wollongong is the third most expensive city in Australia behind Sydney and Melbourne, and various research reports will advise that we need between 5000-7500 additional affordable homes - and that's right now," Ms Adair said.

The trust will also look at expanding their workforce in the future. Although their 45 staff are working well to invest millions of dollars into the community, they'll need extra hands to keep up with demand.

"We know that our current staff are working really well to capacity, but as we expect to literally double our portfolio over the next few years we are confident we will grow our staff numbers," Ms Adair said.

It comes as Colliers International released new data on Thursday highlighting Wollongong is about to have a shortage of new apartments by 2021.

Ms Adair said apartments were appealing to young people, young families and those wanting to downsize and were certainly needed to meet the needs of the Illawarra's growing population.

"We are seeing a real increase in demand for mixed housing," she said.

"So yes apartments, townhouses, duplexes as well as a single dwelling are the types of solutions and the type of stock we need moving forward."

The Housing Trust is the Illawarra's largest community housing provider, and aims to find social and affordable housing to the many families, couples and singles in housing stress.