Married father-of-one Tony Causby, 42, from Leigh, was helping to dismantle scaffolding when he stepped onto a fragile skylight and fell 13m to the floor below.
Atherton-based S&S Scaffolding Ltd was prosecuted by the Health & Safety Executive (HSE) over serious safety breaches following an investigation into the incident at the warehouse on Pennine Way, Skelmersdale on 14 December 2010.
Liverpool Crown Court heard that Mr Causby had helped to erect the scaffolding at the end of October ahead of work to replace damaged cladding and guttering on the roof. He returned to the site on 14 December as part of the dismantling team, although he was employed by S&S Scaffolding as a labourer rather than a scaffolder.
Mr Causby had just returned to the roof with another labourer after his lunch break when he stepped on a skylight, which broke and gave way. He was taken to hospital where he was pronounced dead.
The court was told there were around 80 fragile skylights on one half of the roof, with each one measuring about one metre by two metres. However, the company failed to arrange for covers to be put over the skylights nearest to where its employees were working to prevent them falling through.
S&S Scaffolding Ltd pleaded guilty to single breaches of the Work at Height Regulations 2005 and the Health and Safety at Work etc Act 1974. The company, of Arley Way in Atherton, Greater Manchester, was fined £75,000 and ordered to pay £31,517 in prosecution costs.
HSE inspector Jacqueline Western said after the hearing: "Mr Causby died because S&S Scaffolding didn’t do enough to protect him from the risks of working at height, despite being a specialist scaffolding firm and being fully aware of the dangers of falls.
"It would have been relatively easy to cover the fragile skylights near to where the employees were working to prevent anyone from falling through if they accidently stepped on one.
"Alternatively, netting or crash mats could have been provided under the skylights to reduce the chance of a worker being injured if they fell.
“Sadly, none of these options were chosen by S&S Scaffolding and Mr Causby lost his life as a result."