More than $260 million would be needed to fix structural and safety defects in apartment buildings across Canberra, a new report has found.
The report from Equity Economics also estimated that close to 160 Canberra apartment complexes contained potentially combustible aluminium cladding.
The report's release came as lawyers for the Elara apartment owners appeared in the federal court on Monday, marking the latest chapter in their clients' long-running fight to win compensation for their defect-ridden complex.
The economists' report, which was commissioned by the CFMEU's national office, estimated that apartment owners, as well as state, territory and federal governments, were staring at a $6.2 billion bill to rectify defects in apartment buildings across the country.
The firm's projections, which it described as "conservative", relied on published research about the prevalence of defects in Australia's apartment buildings, along with various estimates on repair costs.
The study only considered apartments built after 2009.
The ACT's rectification bill was estimated at $268 million, which was on par with Western Australia's and significantly higher than South Australia's.
The most expensive defect was combustible cladding, which would cost a combined $176 million to rectify.
The figured was based on the firm's estimate that 157 apartment buildings in the ACT contained combustible cladding.
The firm used the results of an audit of Victorian apartments, which found 1069 buildings contained the material, to estimate the incidence of cladding problems in other jurisdictions, including the ACT.
The cost to rectify water leaks was the next highest, at $69 million, followed by structural defects ($17 million) and fire safety ($6 million).
The study used various media reports to compare repair costs at some of Australia's most infamous buildings, including Sydney's Opal Tower, the Lacrosse complex in Melbourne and Canberra's Elara apartments.
The repair cost per unit at the 118-unit Elara complex was estimated at $158,000.
The Master Builders Association of the ACT this year estimated dodgy construction work had cost the territory economy almost $1 billion since 2010. That figure included all construction work, not just on apartments.
Waterproofing expert Ross Taylor, who has inspected dozens of high-rise apartments in Canberra in the past decade, said Equity Economics' estimates were very conservative.
Mr Taylor knew of at least three buildings, including Elara, with water damage bills exceeding $10 million.
He estimated nine out of 10 buildings had problems with water leaks, with the most extreme cases costing up to $60,000 per unit to repair.
But he said there was a "dearth of good and accurate data" about defective buildings in Australia, which it made it difficult for governments and industry to make "informed" policy decisions.
Strata lawyer Chris Kerin, who is representing the Elara owners, said he had advised three separate owners corporations about cladding issues in the past six months.
As the ACT government had published no detailed information about cladding in Canberra buildings, Mr Kerin said it was difficult to estimate the scale of the problem in the nation's capital.
Mr Kerin said it would be very difficult for many owners to secure compensation for cladding, as only the newest high-rise apartment complexes were covered by statutory warranties.
For that reason, he said the ACT government should consider introducing a compensation scheme for owners, which might include loans or upfront payments.
An ACT government spokesman would not be drawn on a possible cladding compensation scheme, but said it was working with other jurisdictions on an national solution to the issue.
The spokesman said the introduction of a broader, NSW-style building bond scheme was still under consideration.
He noted that the report wasn't based on an actual assessment of Canberra buildings, meaning the findings did not necessarily reflect the "actual numbers of affected buildings or the relative risks".
CFMEU assistant national secretary Dave Noonan said the report laid bare the scale of what he described as Australia's building and construction "crisis'.
"This is the result of the construction industry's obsession with 'deregulation' at any cost, and poor oversight by government," Mr Noonan said.
Meanwhile, Monday marked the start of a federal court hearing in which the Elara owners are hoping to overturn a February ruling rejecting their $10 million compensation claim to the builders' insurance fund.
The hearing will continue on Tuesday.