City of London magistrates heard that Rajveer Goraya, trading as Taj Construction Roofing, was managing four workers as they replaced the roof of a house in Hermitage Way, Stanmore.
But when an inspector from the Health & Safety Executive (HSE) visited the site on 11th July 2013 there were no safety measures in place to prevent the workers from falling.
The trial heard that the workers had used only ladders to access the roof and there was no scaffolding or any other means in use to prevent falls.
Rajveer Goraya, 42, of Laburnum Road, Hayes, was fined £5,000 with £13,743 costs after being found guilty of breaching Regulation 6(3) of the Work at Height Regulations 2005.
After the hearing HSE inspector Jack Wilby said: “Work on a roof without safety measures to prevent people falling, such as scaffolding, is unacceptable.”