Tonnes of rubbish and possessions hoarded in high-rise units are threatening the structural integrity of Melbourne apartment buildings, putting them in danger of collapse.

It is suspected there is hoarding in most large residential buildings in Victoria. This has prompted growing concerns about the threat to public safety through fires, vermin and building damage.

Experts are now calling for a national hoarding and squalor taskforce, saying many people living with hoarding disorder, or in extremely unsanitary conditions, are not getting the professional help they need.

"It's like a sleeping giant," Melbourne psychologist and hoarding specialist Dr Chris Mogan said.

"This is problem that can affect between 400,000 and a million Australians."

The Metropolitan Fire Brigade has received advice the structural integrity of four Melbourne apartment buildings could have been undermined by residents cramming their homes with papers, furniture, rubbish and other possessions.

"There are concerns regarding how much stress a building may withstand when the high fuel load and the water load required to extinguish a fire are combined," the brigade found.

At a number of homes, glass has been smashed out of windows due to the expanding mass of belongings inside.

The spread of illness is also an issue. In one recent case in an affluent Melbourne suburb, rats and pigeons from one apartment were making their way into neighbouring homes.

Assistant chief fire officer Rob Purcell said the floor of that unit was overloaded, "compromising the ability for the structure to maintain its integrity".

"So if you take one floor down you're probably going to fall into the next one – then you're wiping out the living areas for everyone in the complex."

Highlighting the growing impact on neighbours, new research by the brigade has found 36 per cent of hoarding or squalor incidents take place in apartments or flats – a 7 per cent increase in three years.

Mr Purcell said the MFB was unable to disclose the location of the properties where structural integrity was a concern due to privacy reasons, but said agencies were working to reduce the load.

Municipal Association of Victorian president Bill McArthur said council officers had powers to inspect properties suspected to be unsafe, either with the owner's permission or via a warrant.

"A building order can be issued if there is non-compliance with a building notice, or an emergency order can be issued if there is an immediate danger to life or property due to the condition of a building," he said.

Stonnington Council, which has developed its own hoarding and squalor protocol, said while on the surface hoarding and squalor cases can seem straight forward, they were actually quite complex.

"Where mental health issues are at the forefront of an individual case, the priority is to support the resident, while resolving the hoarding and or squalor issues to the satisfaction of the community," acting chief executive Karen Watson said.

There is overwhelming evidence forced clean-ups of hoarding properties do not work in the long term and can cause extreme distress to the person involved – in some cases prompting suicide.

Hoarding disorder is broadly defined as the persistent accumulation of objects or animals resulting in extreme clutter and was classified as a distinctive psychiatric condition in 2013.

But Australian mental health experts say there is almost no funding for treatment and research of hoarding, and many people are not getting sufficient expert help.

Dr Mogan said hoarding could "lead to death", through fire, electrocution, disease-related neglect and accidents in the home.

Extreme hoarding and squalor are more common in older people, meaning problems are only set to balloon in Victoria as the population ages.

And no area or suburb is immune.

The MFB's latest hoarding and squalor study was expanded to include the Country Fire Authority's jurisdiction. It found 188 incidents between 2012 and 2015 with links to severe clutter or squalid homes including 24 in country or outer urban areas.

Do you know more? Email aisha.dow@fairfaxmedia.com.au