A construction firm has been fined £20,000 after a man suffered horrific burns to his legs at its depot in Sevenoaks.

O'Keefe Construction (Greenwich) Ltd, of St Andrews House, Dreadnought Street, Greenwich, pleaded guilty to breaching a section of the Health and Safety at Work etc Act 1974.

Sevenoaks Magistrates' Court heard that on October 26, 2009, an 18-year-old man, who asked not to be named, was in a shed at the site spraypainting a lighting tower. The employee used thinners in the process and spilled some on his trousers.

When he walked across the shed to go to his locker and find a change of clothes, he walked near a gas burner which was being used in the workshop. His clothes caught fire and he ran outside where colleagues helped who put out the flames.

The worker suffered burns to both legs, his left arm and his hand. He was in hospital for 16 days, six of which were spent in intensive care. Since then he has undergone skin grafts and been unable to work for six months.

An investigation by the Health and Safety Executive (HSE) found the spray shed had several health and safety failings. Paint containers should have had lids on and been stored in fire-resistant boxes. The company should also have been aware the mixing of paint and thinners in the shed would lead to a potentially explosive atmosphere, so a gas burner with open flame should not have been used in the same space.

The company had executed a risk assessment but had not implemented the measures identified. A further management action plan, dated three years after the original assessment, re-iterated these measures, but they had still not been put in place.

O'Keefe Construction pleaded guilty to breaching section 2 (1) of the Health and Safety at Work etc Act 1974. The company was fined £20,000 and ordered to pay costs of £6,329.