Speaking at a forum called by retirees worried about the cost of housing and homelessness in Canberra, Ms Le Couteur said buildings slated for demolition could be used as temporary shelters.

She pointed to a "pop-up homelessness shelter" scheme in Melbourne, and also to Safe Shelter's use of churches in Canberra for the homeless, but she said the Labor government had originally baulked at changing zoning permission for Safe Shelter's scheme.

The idea was supported by Liberal housing spokesman Mark Parton.

The forum, called by residents of Haydon Retirement Community in Bruce, criticised the ACT government for overcrowding the housing market, federal taxes which incentivised housing investment, low wages and a lack of social services.

ACT Housing Minister Yvette Berry did not attend.

Mr Parton said the price of land in Canberra had increased dramatically and the government was only growing the city "up" by approving more apartments.

"There is no private affordable housing in the ACT," he said.

He pointed to a 2015 survey which showed the majority of Canberrans would prefer to live in a standalone house.

Federal Labor MP Andrew Leigh said negative gearing had incentivised housing investments and have "crowded people out" in Canberra, and should be abolished.

Any cuts to corporate tax would make the problem worse.

"You cut personal income taxes, you cut company taxes, you cut as many taxes as possible and then you wait for the crisis to happen," Mr Leigh said.

He said government using this strategy, known as "starve the beast", would then cut welfare to reduce debt.

But Mr Parton argued strongly for business incentives and lower personal taxes.

His father had come from a poor background and run his own grocery store, aided by low taxes for businesses.

"What I fear is that if we do what Mr Leigh suggests we do, one of things we end up doing is removing incentivisation," he said, pointing to past regimes in South America which he said had moved into an "extreme socialist realm". When you remove incentives for people to work hard, they don't, he said, naming Venezuela and Chile.

ACT Council of Social Service executive director Susan Helyar said homelessness was a massive problem which needed action on both a federal and local level.

"There needs to be $100 million put into this problem," Ms Helyar said, calling on the ACT government to require portfolios to report on how their spending would impact housing and support services, and to increase the amount of affordable housing in Canberra.

Ms Le Couteur said instead welfare payments should be increased and a more progressive tax system should be introduced.

The forum follows a report indicating the number of rough sleepers in the capital has doubled over five years, with the ACT turning away more than 1000 people seeking housing assistance last year.

Ms Le Couteur and Mr Parton said the number of homeless in Canberra could be much higher than the official figure of 1600 identified in the 2016 census.

Forum organiser Professor Bob Douglas said the residents hadn't called the meeting because they were concerned they were facing homelessness themselves.

"Just concerns about the way the world was travelling," Prof Douglas said.

Liberal Senator Zed Seselja was due to attend but was unable due to events engulfing Parliament House.