Defective balconies might be commonplace in apartment blocks across the country, requiring costly repairs and putting the safety of residents at risk.
More than 550 damaged balconies had been found by Cladding Safety Victoria during inspections for flammable cladding, as of October 2022.
The authority is concerned the issue is widespread in unit blocks across Australia and not just confined to buildings that might have cladding issues.
Its research report showed half of all buildings that need to have dangerous cladding removed also had unrelated defects.
About one quarter had leaking balconies, terraces or balustrades that caused structural damage.
Almost one in five buildings with balcony issues also had black mould due to waterproofing issues.
"While the source of the issue is primarily attributed to the builder, the problem of building defects more generally is, in Cladding Safety Victoria's view, symptomatic of broader underlying levels of non-compliance with the National Construction Code," the report said.
Common areas of non-compliance were serious fire safety deficiencies, inadequate waterproofing and black mould in new buildings.
The authority's chief executive Dan O'Brien said balcony defects can cost up to $15,000 to fix and encouraged all apartment owners to check that their balconies were safe.
"For the buildings we've looked at, we've seen some substantial defects and we've got them fixed," Mr O'Brien told reporters on Friday.
As of October 2022, 339 buildings received funding to cover the cost of removing dangerous flammable cladding and that process had been completed on more than 270.
About two-thirds of buildings involved were low-rise apartment blocks.
Unexpected defects delayed remediation work by a minimum of about three months but was not covered by the government-funded cladding safety removal program.
The research paper said many insurance policies would not cover works related to faulty workmanship, general wear and tear or building defects, leaving owners to pick up the costs.
It found balcony defects tended to be more prevalent on buildings that contained timber frames and structural beams, however buildings with concrete slabs had noticeable issues with a lack of waterproof membranes.
The $600 million cladding removal project was announced in 2019, two years after the Grenfell Tower fire in London that killed 72 people.
The Victorian government has been contacted for comment.
