The 21-year-old, who does not wish to be named, fell on June 7 last year at a development on Oxshott Rise where a large detached home was being built.
Staines Magistrates’ Court heard that he was helping to build a flat roof with a number of roof light openings for Horley-based D&R Carpentry Ltd.
He fell through one of the openings and almost three metres to the ground below.
An HSE investigation found there was nothing in place to prevent or mitigate a fall, such as safety decking beneath the roof and openings, or a soft landing system.
Magistrates were told the company had previously been warned to consider the risks posed by falls from height by HSE following site inspections in January and February 2007 to a site in Hurst Green, East Sussex.
This resulted in written advice and a Prohibition Notice being served that required work to stop and immediate improvements to be made.
D&R Carpentry, of Horley was fined £5,000 and ordered to pay £4,407 in costs plus a further £5,000 in compensation after pleading guilty to safety breaches.
After the hearing, HSE inspector Denis Bodger said: “Work at height is inherently fraught with risk, and falls remain the single biggest cause of deaths and serious injury in the construction industry.
“It is therefore essential that all work at height is properly assessed, managed and monitored to ensure it is carried out safely, and that all necessary precautions are taken to prevent falls and protect workers.
“There were clear failings by D&R Carpentry in this regard at the Cobham development, and an employee suffered serious injury as a result. He could easily have been killed or left with life-changing injuries.”