Safety inspectors visited improvement work at the premises of Haz International in Hatfield in September 2009 and again in July 2010 after receiving complaints about unsafe working at height.
During the 2009 visit, inspectors served a Prohibition Notice on the company preventing further work until improvements to the scaffolding had been made.
A further two prohibition notices were served in July 2010, as poor working practices regarding work at height had continued.
Watford Magistrates’ Court heard that the firm and its company secretary failed to heed the warnings.
Haz International admitted three breaches of health and safety legislation and was fined £54,000 and ordered to pay £13,280 costs.
Company secretary Mark Adams of Twickenham was fined £3,600.
HSE Inspector John Berezansky said: “It was pure luck there wasn’t a serious incident at this site.
“Even thought they had received a previous Prohibition Notice and further advice from HSE and their own Construction Design and Management Coordinator (CDMC) they failed to heed it.
“HSE will not hesitate in prosecuting poor performing companies and any individuals within those companies who place persons at risk.”