Glebe Coroner's court also heard on Monday of questionable training and workplace dangers as it inquired into the death of 19-year-old Marcus Wilson after he worked one day in the federal Labor government's subsidised home-insulation scheme.
The 19-year-old was the third person to die while working on the controversial program.
Mr Wilson collapsed on November 2009 from hyperthermia after working in 45C-plus heat.
He was put into an induced coma and later died from organ failure.
Mr Wilson, who had no experience in the industry, had agreed to work on that hot Friday for a friend who was sick.
Co-worker Collin Cini noticed Mr Wilson looked unwell at a job in St Clair, in Sydney's west, but did not realise he was in trouble.
"I am sorry for the role I played, I'm sorry to the family," Mr Cini told the inquest.
Mr Cini had been working only for some weeks as a contractor for Pride Building NSW, which later was liquidated. He also had no experience but had attended a training course organised by the owner of Pride, Ryan Glover.
The instructor arrived late and Mr Glover pressed for a shortened course, which would have lasted less than 60 minutes, instead of the scheduled four hours' training, Mr Cini told the inquiry.
The course, delivered by Comsec Training in Lidcombe, did not cover installation or risk assessment, the inquiry heard.
Contractors did not sign agreements with Pride, there was no training for working in elevated, enclosed spaces and no one was supplied with thermometers to gauge roof cavity temperatures, the inquest heard.
Alan Lawson, who was in the roof insulation business for 45 years, worked as a contract inspector for Pride from October 2009 to January 2010.
He attended the course and said answers to the test questions were already written on the board.
"They didn't actually go into laying instruction," Mr Lawson told the inquiry.
He also said the course did not include information about working in an enclosed space, but it did address the impact of heatstroke.
Mr Lawson told the inquiry he recommended installers not work when the outside temperature exceeded 32 degrees but he believed Mr Glover would not let the heat delay a job.
"I knew that was the stand he would take," Mr Lawson told the inquiry.
"That the work would carry on."
The inquest continues on Tuesday.
ninemsn.com.au 20 Aug 2012