Alan Campbell, 47, was fitting a loading platform on 19 June 2012 when he fell. He suffered two bleeds to the brain and was kept in an induced coma for more than three weeks. A metal plate also had to be inserted into his forehead to reshape his face.
The Health and Safety Executive (HSE) and Scotland's prosecution service the Crown Office and Procurator Fiscal Service found Anglian Windows had not provided sufficient information, instruction, training and supervision to employees who loaded and unloaded equipment from van roofs.
The company pleaded guilty and was fined £10,000 for breaching Section 2(1) of the Health and Safety at Work Act 1974.
HSE inspector Ritchie McCrae said: "On this occasion, Anglian Windows failed to control the risk of falls from van roofs as the company was entirely reliant on an instruction which was not properly communicated and was not monitored to check compliance."