Kewie Doherty's company, C J Langs, was also sentenced after inspectors from the Health and Safety Executive (HSE) found unsafe work-at-height practices, a lack of suitable equipment, and untrained operatives working without supervision.
They had visited the site in Sherborne Gardens, Ealing, following an accident in January 2017, Westminster Magistrates' Court was told.
C J Langs pleaded guilty to breaching reg 15(2) of the Construction (Design and Management) Regulations 2015 over its failure to plan, manage and monitor the work. It was fined £80,000 and ordered to pay £6,000 costs.
Doherty pleaded guilty to breaching s 37(1) of the Health and Safety at Work Act. He was disqualified from being a company director for three years and ordered to carry out 150 hours of unpaid community work. He must also pay costs of £1,673.