Scott Gregory Walker had been out with a mate and was on his way home on Friday, June 12, 2015, when he drove past Greenmountain Food Processing at Cominya in the Lockyer Valley west of Brisbane.

Mr Walker thought he saw smoke pouring from the roof of the plant and believed the factory was on fire before discovering it was steam leaking from the factory's boiler.

He contacted a repair contractor, and while on a mobile phone call, he was asked to identify the source of the leak.

After accessing a platform in fading light, Mr Walker climbed onto the roof in a bid to identify the source of the leak before he fell through a fibreglass panel installed to repair a rusted section of the roof.

The father of two plummeted more than seven metres and was knocked unconscious when he crashed onto the concrete floor of the deserted shed.

The manager, who was aged 32 at the time, suffered severe injuries to his spine, both legs and wrist.

Despite being badly injured, Mr Walker had to drag himself out of the shed where he was found by a truck driver delivering stock to the meatworks.

After extensive surgeries and ongoing medical treatment, Mr Walker has suffered permanent and debilitating injuries.

He forgets things and is slower in processing matters and permanent orthopaedic injuries mean he cannot return to work as an electrician or do manual work that requires him to crouch.

In a decision handed down in the Queensland Supreme Court, Justice Peter Applegarth found Mr Walker was motivated by "a sense of duty".

"The whole plant depended upon this single boiler working. As Mr Walker said in his evidence: 'If it doesn't run, the plant doesn't run either'," Justice Applegarth said.

"If the source of the leak was not identified on the Friday evening of the incident, then there would have been substantial delays on the Saturday in locating it."

Justice Applegarth found there was no prohibition on staff and maintenance workers from going onto the roof or any requirement to wear a safety harness or safety training conducted, he said.

There was also no barrier to prevent access or signs warning of the dangers of the fibreglass panels.

"He engaged in objectively risky activity in discharging his duty as a Maintenance Manager in a circumstance of perceived urgency," Justice Applegarth found.

"Nothing caused him to stop and think about the potential danger to his own safety. Nothing told him that he should not go on the roof at all, or at least not go on the roof without a safety harness."

Greenmountain Food Processing was found negligent and ordered to pay a total of $967,383.39.

Australian Associated Press