Are granny flats the answer to Australia's housing, homeless crisis?

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Could the humble granny flat help solve the housing problems crippling capital cities across Australia?

Adelaide education strategist Roger Hunter has been named a finalist in the South Australian Government's Share Challenge, a competition looking to unlock the value in under-used assets and resources for broader community benefit.

"I'd been looking at the idea of how to provide better accommodation for people who are houseless," Mr Hunter told ABC Radio Adelaide's Drive program.

He said he was inspired to enter the competition after he recently transformed an unused double garage into a granny flat for his visiting mother.

"We knocked down the garage and built a small granny flat with a little shower, kitchen, living room and a proper bed," he said.

"She would come out for two or three months at a time and absolutely love it."

The State Government provides funding for crisis accommodation but demand is outstripping supply.

Mr Hunter said if other people had unused space or sheds in their backyards, this funding could be redirected to help transform these underutilised spaces into liveable dwellings for those in need.

"If you get a really smart architect, you can actually live a lot better," Mr Hunter said.

Leftover funding as well as rent assistance payments could be used to help build a support fund for those trying to return to mainstream housing.

Mr Hunter said his idea would also provide stability for people being moved from location to location on short-term leases.

"A homeless person is able to stay there for five years, and at the end of the five years [the landowner] gets to keep the house," Mr Hunter explained.

The concept is one of 10 finalists in the Share Challenge competition. The winner will be announced in October.

We acknowledge Aboriginal and Torres Strait Islander peoples as the First Australians and Traditional Custodians of the lands where we live, learn, and work.

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