Mark Arbib was the essential backroom political manipulator, employing skills and clout honed in the cut-throat murkiness of Labor's Sussex Street headquarters.

Former Labor senator Mark Arbib. Photo: Andrew Meares

Confusion reigned in the Rudd government over which minister was actually in charge of the home insulation program, an inquiry has heard.

It was unclear whether former environment minister Peter Garrett or senator Mark Arbib was in control of the botched scheme, which has been blamed for four deaths and hundreds of house fires.

Mr Garrett's adviser Matt Levey has told a royal commission into the Home Insulation Program (HIP) that a document was even drafted to establish the relationship between the two ministers in relation to the scheme's development.

Mr Garrett found it difficult to guide the program because of Mr Arbib's involvement, he said.

"Minister Garrett obviously had policy authority, but Senator Arbib was doing an awful lot of work on the program," Mr Levey's statement to the inquiry read.

"I never fully understood where his [Arbib's] involvement ended or began. I do not recall whether this was ever satisfactorily resolved.

"It made it very difficult for minister Garrett to drive the direction of the program."

Mr Levey also told the inquiry that staff in Mr Garrett's department became confused and anxious about changes to the program by Mr Arbib and the co-ordinator-general, Mike Mrdak.

But he agreed those changes couldn't happen without Mr Garrett's approval.

The Rudd government announced the home insulation scheme on February 3, 2009, to stimulate the economy during the global financial crisis.

At the time, Mr Arbib had been charged with co-ordinating government stimulus programs.

Senior environment department staffers initially designed a regional delivery model that had the capacity for installer training, but it was changed to a more centralised scheme following a meeting involving Mr Arbib and Mr Mrdak in March 2009.

The scheme ended up being inundated with low-skilled workers who required only a general safety induction before entering ceilings.

The inquiry, which began in Brisbane on Monday, has heard how bureaucrats were repeatedly warned insulation installers would die if safety issues weren't addressed.

They were also alerted to the electrocutions of three New Zealand men working under a similar program in 2007.

But Mr Levey said department staffers didn't pass on the warnings to Mr Garrett.

"From my perception, it came as a genuine surprise to the minister that there were serious safety issues with the HIP," his statement said.

Matthew Fuller, 25, became the first worker to die under the scheme when he was electrocuted while laying insulation sheeting at a house in Brisbane's south on October 14, 2009.

Queenslanders Rueben Barnes, 16, and Mitchell Sweeney, 22, and Marcus Wilson, 19, of NSW, were also killed.

The inquiry before commissioner Ian Hanger will resume on Monday.

AAP

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