The post advertised the single bed for $75 a week in the hallway of a two bedroom house in North Hobart which is already shared by two boys living in one room and a couple living in the other room.

Tenants Union senior solicitor Ben Bartl said the Gumtree advertisement highlighted the shortage of affordable housing and rises in rents.

Mr Bartl said under the Residential Tenancy Act any space, whether in a hallway or under stairs, could be advertised for rent.

"It is a double edged sword because there is a huge shortage of rentals and it is not ideal that people are in unsuitable areas such as hallways but we understand a lot of people are having trouble paying their rents," he said.

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"It's probably just the tip of the iceberg.

"We know many international students live in overcrowded houses.

"There are no minimum standards about how many people can live in a house."

Mr Bartl said in the past 12 months rents had risen 7 per cent in the North, 9.7 per cent in the South and 0.5 per cent in the North West.

"We have sympathy with tenants struggling to pay the rent and sometimes if they are not on the lease they will not have any legal rights," he said.

Last week's state budget announced $20 million has been brought forward into the 2019-20 and 2020-21 budgets from the forward estimates, as part of the delivery of Stage Two of the Affordable Housing Strategy, to address housing stress with priority.

Treasurer Peter Gutwein said he had not seen the Gumtree advertisement but it was incumbent on landlords to abide by the Tenancy Act.

A government spokesman said they would not comment further on the advertisement not knowing the full circumstances behind the Gumtree post.

Greens leader Cassy O'Connor said the sad thing about the advertisement was there was probably a desperate person who sees sleeping in a hallway as a viable option.

"That's the point we have come to," Ms O'Connor said.

"When you've got landlords advertising a bed in a hallway for $75 a week, you know you've got a serious housing crisis and a government that is not taking this serious enough."

Ms O'Connor said there needed to be stronger action from government on cracking down on landlords who overcharged tenants or who put tenants in unsuitable and unsafe situations.

"The problem we have is, we have so many people in housing distress that they would be willing to accept this through substandard and depressing option for a home," Ms O'Connor said.

Labor Clark MHA Scott Bacon said there was no doubt people seeing that advertisement on Gumtree would be disturbed at how difficult it was for Tasmanians to find housing.

"We know this is a government that has been told for two years there is a housing affordability crisis. They aren't taking the issues seriously," Mr Bacon said.