The incident happened while London-based Balfour Beatty was running the site at Richmond Park, Croft, Sheffield, on 2nd March 2015.
Newcastle Crown Court heard that a worker was on the first floor of a new-build domestic property when the floor gave way at one side.
The worker and around 70 building blocks slid 2.4 metres vertically to the ground resulting in him suffering fractures to bones in his foot.
An investigation by the Health and Safety Executive (HSE) found that the supporting joists of the first floor had not been fully installed, leaving it unstable.
“It is vital that companies [follow] design instructions and ensure that structures are stable,” said Alan Sheldon, inspector for HSE.
“This incident could have been much more serious for a number of workers and should act as a reminder to everyone within construction that protecting workers’ health and safety is vital in such a potentially dangerous industry.”
Balfour Beatty pleaded guilty to breaching construction regulation and in addition to the £230,000 fine was ordered to pay costs of £11,915.