A bureaucrat who regularly briefed Peter Garrett on the home insulation scheme roll-out says the then-minister wanted to rapidly deal with safety issues once he was made aware of them.

Malcolm Forbes, second-in-charge of the Environment Department when the scheme was set up, has told the Royal Commission into the Home Insulation Program in Brisbane that the department was working to a "horrendous" timeframe to get the program in place.

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Mr Forbes, then the Environment Department's acting deputy secretary, said Mr Garrett "expressed more and more frustration" as time went on.

"The minister was keen to get the HIP (Home Insulation Program) up and running quickly, as he had made ... a commitment to the prime minister to do so," Mr Forbes said.

"In particular he became concerned about the quality and skill of installers and their ability to deliver the HIP.

"He was also concerned at the scale of rorting that appeared to be underway by some operators."

Mr Forbes said Mr Garrett was "deeply disturbed" by four worksite deaths and wanted "to move rapidly on safety issues once he became aware of them".

He accepted there were "significant deficiencies" with the scheme's compliance regime.

"As I recall (Mr Garrett) was responsive to suggestions to change guidelines, tighten processes and hurdles for installers," Mr Forbes said.

The inquiry is considering whether the former Labor government and its staff failed to heed safety warnings before four workers died on the job in 2009 and 2010.

The program was set up in 2009 by former prime minister Kevin Rudd and Mr Garrett.

Hundreds of house fires broke out as the program was rolled out, many of them in ceilings where foil insulation had been incorrectly installed.