The inquiry into the CFMEU in Queensland has been extended through to December by the Crisafulli government and will resume on Tuesday.
Months of hearings have exposed evidence of bullying, intimidation and violence on worksites.
Nigel Hadgkiss, former commissioner of the Australian Building and Construction Commission, will return to the stand on Thursday after providing testimony in April.
He urged the state to adopt a building code of practice to rein in the CFMEU, telling the inquiry that reform would not be possible until contractors were more frightened of the regulator than the union.
Mr Hadgkiss said contractors were unable to challenge the union's power on worksites because they were reliant on work from the former state Labor government, with whom the union had a close relationship.
"It was biting the hand that was feeding them," he said.
Also returning to the inquiry will be the ABCC's Wayne Jenkinson, who is director of operations for the commission's northern region.
Mr Jenkinson told the inquiry in April that he believed the state's building code had been torn up by the former government at the CFMEU's behest.
Two high-ranking officials from the Office of Industrial Relations, Andrea Fox and former deputy director-general Kym Bancroft, are expected to give evidence across Tuesday and Wednesday.
Also taking the stand will be Graham Easterby, former licensing manager of the Queensland Building and Construction Commission.
Mr Easterby left the role in September 2021, citing "inappropriate influence/directions given to carry out my role as issued through senior management from board members, including how to regulate safety matters, and the granting of licenses".
The inquiry, which is being heard before Commissioner Stuart Wood, had originally been due to deliver its final report on July 31.
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