A small group of private certifiers have signed off on 130 buildings with compliance problems, including allowing residents to move into one property that did not have toilets or taps fitted.
The six offenders have been hit with 111 disciplinary actions since 2005, accounting for about a quarter of all such penalties.
The Owners' Corporation Network, the peak body for apartment owners, said the repeat offending was further evidence of "deep systemic problems" in the industry.
"It is symptomatic of a government that has forgotten how to regulate," chairman Phil Gall said.
"The Building Professionals Board was overseen by the planning minister until 2016, when it became the responsibility of the minister for better regulation. "Three years later we still have serious problems," Mr Gall said. "How did the ministers involved not know this reform wasn't working?"