"The practitioner registration system does not ensure that the only practitioners who are registered are qualified, competent and of good character, and the disciplinary system is not protecting consumers, as current sanctions are ineffective in deterring practitioner misconduct."

Nor are consumers properly protected in the event of a dispute with builders, Mr Doyle found.

Consumer Affairs' conciliation and dispute resolution functions "provide only limited consumer protection because they lack enforcement powers", it does not have the power to enforce the negotiated outcomes.

He said successive governments had been made aware of the lack of protections for consumers, and had failed to act. "These issues now require urgent attention."

Adam Fennessey, the secretary of the department of environment, land, water and planning, said the government was committed to strengthening protections against home-building malpractice. It will work with the government and the Victorian Building Authority and Building Practitioners Board to strengthen consumer protections.