A survey of homeless people in the Hobart region has found that more than one fifth had been in foster care as children, and almost half had been to prison.

The Salvation Army and Common Ground Tasmania, which provides housing services for vulnerable people, have surveyed 342 long-term homeless people since 2011.

Seventy per cent of respondents were tri-morbid- meaning they had a dual diagnosis of physical and mental illness and also reported substance abuse.

Liz Thomas, managing director of Common Ground Tasmania, said she hoped the data collected over four years would help accommodation providers improve their services for chronically homeless people in Hobart and its surrounds.

"We really didn't know what we were going to find, it actually provides information that hasn't been able to be quantified before," she said.

"So if we know if you're in foster care there's a one-in-four chance you will end up chronically homeless; what can we do to stop that likelihood or reduce it?"

Fifty-six per cent of those surveyed said they had been victims of violent attacks since becoming homeless.

'Always looking over my shoulder'

Jo Robinson, 52, was homeless for 35 years before moving into a Common Ground unit four years ago.

She said she had lived a life very close to the edge and continuously made unhealthy and destructive choices.

Running away from home at 13 led to years spent as a prostitute, periods of homelessness and drug addiction.

"I was used to living this life," she said.

Jo Robinson said it was particularly hard to find housing options as a homeless woman. ( ABC News )

"In retrospect, what a sad way to live.

"At 46 I had to take a good look at myself."

Ms Robinson found herself sharing a room with a friend who also had nowhere to call home.

"We were both middle-aged women, no dependents, we were judged, then dismissed," she said.

"We were even contemplating how we could go to jail as we had a far better chance to be housed when released."

Finally she was placed in housing at Common Ground Tasmania's Goulburn Street units in Hobart.

"There's the safety, my lifestyle always was dangerous, I didn't know who was going to knock at the door wherever I was," she said.

"The security and the people that live there, the community we have built ... those people in that community care about you."

Ms Robinson said it was especially hard to find housing options as a woman.

She found she could not get places in women's shelters without dependent children, and was uncomfortable with homelessness shelters with mostly male clients.

"I was always looking over my shoulder, I wasn't the only woman who was homeless, I found that there was many women homeless, we're often overlooked," she said.

"It is very hard for women, especially over 35."

She said she wanted to see more Common Ground units built to meet demand.