Karen Cranfield says the three-bedroom unit she rents is nice, but not perfect.

Key points: Hobart had the highest rent increases and the lowest rental vacancies in the September quarter

Hobart had the highest rent increases and the lowest rental vacancies in the September quarter Tenants' Union of Tasmania is pushing for a cap on rent increases

Tenants' Union of Tasmania is pushing for a cap on rent increases The real estate industry says there is no easy answer to the property shortage

The handles are falling off some cupboard doors, there's only a small garden, and she's had to patch up a few holes in the walls.

It's also not cheap. She lives in Rokeby, a suburb of Hobart, and said her rent had jumped from $320 to $400 a week within 12 months.

Ms Cranfield's weekly rent is now only $100 short of the suburb's median personal income.

"It's off the show, I nearly had a meltdown actually," the cleaner and gym instructor said.

"This is meant to be the area where lower-income people can afford living and it's just ridiculous, absolutely ridiculous."

Tasmania has been in the grips of a housing crisis for more than 18 months.

The latest Domain rental report shows Hobart had the nation's highest year-on-year rent increase at 9.8 per cent for houses and almost 13 per cent for units. Wages rose only 2.4 per cent in the same period.

Tasmania's capital also had the lowest vacancy rate of any capital city market at just 0.5 per cent. This equated to only 120 available, vacant rental properties at the end of the September quarter.

Tony Collidge, from the Real Estate Institute of Tasmania, said it was a difficult situation.

"The really concerning thing we're seeing at the moment is we're seeing the number of investors aren't coming into the market … which could result in there being fewer investment properties available in the marketplace," he said.

"That's going to put all sorts of additional pressures on the shortage of property we've got already."

Tenants have to prove rent is unfair

The Tenants' Union of Tasmania has been fighting for changes to the law that would ease stress for renters like Ms Cranfield.

Principal solicitor Ben Bartl said the union wanted a cap on rent increases and to make it so it was on landlords to prove any rise in rent was reasonable.

Current Tasmanian law dictates it is up to tenants to prove rent increases were unfair, and Ms Cranfield said when she wanted to challenge her real estate agency she had been advised to first look at the rents asked on other Rokeby properties.

Tony Collidge says there is not easy answer to the shortage of properties. ( ABC News: Ellen Coulter )

"We get calls every day from renters who are concerned about either having to stay in properties where the rent is going up or forced to look for a rental property that's going to potentially put them in rental stress," Mr Bartl said.

"Unfortunately, the law in Tasmania is that the rent can go up by whatever amount the market dictates.

"We have many cases where Tasmanians are looking at potentially a $30, $40, $50 a week increase, and unfortunately there's not a lot that can be done because in many cases that is what the market is allowing."

Mr Collidge said there was no easy answer to the shortage of properties in Hobart, pointing to a lack of builders and what he called an "antiquated planning scheme" as contributing to the problem.

"We could put 1,000 properties into Hobart tomorrow and they'd all be consumed within weeks," he said.

"We're chasing our tail all the time."

Ms Cranfield, who lives with three of her sons, said she had raised one adult son's board and taken on more cleaning shifts to make ends meet on the back of the rent rise.

She urged compassion from real estate agencies and landlords, noting the state was already battling to house its homeless.

"The poor are just getting poorer and the rich are getting richer, they're only looking after themselves," Ms Cranfield said.