Mark Clarke was helping to renovate his employer's property Heathfield Barn at North Petherton, Bridgwater when the incident occurred on 11 October last year.
Taunton Magistrates Court heard that he was working on a gable end wall when he fell from a trestle work platform. Although some measures had been put in place to prevent such a fall, these were described as inadequate.
Mr Clarke, aged 55, from Bridgwater is no longer able to work in the construction industry as a result of the injuries he sustained.
UK Storage Company (SW) Ltd, of Unit 3 East Quay, Wylds Road in Bridgwater, pleaded guilty to breaching Section 4(1) of the Health and Safety at Work etc Act 1974. The company was fined £5,000 and ordered to pay £2,680 in costs.
After the hearing, Health and Safety Executive inspector Steve Frain said: "Employers need to ensure there is adequate supervision and fall protection in place while renovation activity of this nature is undertaken.”