Scott Massie landed on his back, fracturing his spine in several places and breaking two ribs during the accident on the building's first floor.
No one heard him call out for help and he had to crawl back up to the floor he fell from before being found.
The 37-year-old suffered eight fractures of the vertebrae, two broken ribs and was in hospital for almost eight weeks. He was diagnosed as having permanent damage to his lower back.
Mr Massie had been replacing a floorboard over a hole in the floor, one of several that were part of a hoist shaft to lift materials up to higher floors. But as he moved the board into position, it fell through the hole, followed by Mr Massie himself.
The incident, at a hotel in Market Street, Aberdeen in October 2009, was investigated by the Health and Safety Executive (HSE) which, just a few weeks earlier, had served an Improvement Notice on principal contractor Aberdeen Fabrication Limited (A-FAB) following a site inspection. Mr Massie was employed by Riverside Construction (Aberdeen) Limited, which had been subcontracted by A-FAB.
At Peterhead Sheriff Court yesterday A-FAB, of Carden Place, Aberdeen, was fined £45,000 after pleading guilty to breaching Section 3(1) of the Health and Safety at Work Act 1974. Riverside Construction (Aberdeen) Limited, of Bon-Accord Crescent, Aberdeen, was fined £30,000 after also admitting a breach.
HSE said A-FAB had failed to address the safety issues in the Improvement Notice and both companies had failed to take suitable steps to prevent serious falls.