Steven Watson (30) from Tyne and Wear fell through the roof while dismantling the disused Brymon Airways hangar on 16 December 2006.
Mr Watson fell approximately 30 feet onto the concrete floor below, and died at the scene from multiple internal injuries.
He had previously cut through the PVC tarpaulin roof and fell through the section he had cut away as he climbed back to a mobile platform.
Bristol Crown Court heard that there were no other protective measures in place and Rubb Buildings should have ensured that Mr Watson had no need to climb directly onto the roof.
Rubb Buildings pleaded guilty to breaching safety law and was also ordered to pay costs of £49,000.
HSE inspector, Steve Frain, said: “The company failed in its duty to ensure there was a properly planned and supervised means of working – there should have been no need to work directly on the roof.
“Falls from height can be extremely serious risks and adequate safety measures must be in place to protect all workers in order to prevent tragic incidents such as this.”