Hawarden Roofing Supplies & Contractors Limited was prosecuted by the Health & Safety Executive (HSE) following the incident at a domestic property on Madeley Close in Broughton on 13 October 2009.
Mold Magistrates' Court heard that 23-year-old Mark Cain, from Broughton, was working on the removal and replacement of a garage roof when he fell more than two metres to the ground below.
He suffered whiplash and two broken bones in his lower back, and has been unable to return to work due to persistent back pain.
The court heard the company failed to notify the HSE of the incident and therefore an inspector did not visit the site to ensure work was being carried out in a safe manner.
HSE was eventually made aware of the incident and a subsequent investigation was launched. It found that the company had failed to properly plan and supervise work at height activities, and ensure that appropriate measures were in place to control the associated risks.
Hawarden Roofing Supplies & Contractors Limited of 33 Chester Road, Queensferry, Deeside, Flintshire pleaded guilty to breaching Regulation 4(1) of the Work at Height Regulations 2005. It was fined £3,000. It also pleaded guilty to breaching Regulation 3(1)(b) of the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995 and was fined £1,000. The defendant was also ordered to pay costs of £2,500.
Speaking after the hearing, HSE inspector, Will Gretton said: "Falls from height continue to be the biggest cause of fatal injuries within the construction industry. The type of injuries for people who fall from height while at work, and survive, can be life-changing, ranging from debilitating back injuries to paralysis.
"This incident was totally foreseeable, but Mr Cain has suffered significant injuries as a consequence of inadequate planning and supervision while working at height.
"Had the incident been reported to the HSE, an immediate prohibition notice would have been served on the site and all work stopped until the correct and reasonably practicable measures put in place."