The accident happened during repairs to fix leaks at the property in Seaton Avenue, Felixstowe, Suffolk, in September 2016.
An investigation by the Health and Safety Executive (HSE) found there was no edge protection around the roof and the worker and his colleague were using an unsecured ladder to gain access.
The ladder slipped as the roofer stepped on to it, causing him to fall. He sustained bruising to his head and hearing damage.
HSE investigators found the work had been inadequately assessed and there was no system in place to ensure the correct equipment was being used for working at height. Supervision of the job too was inadequate.
RFT Repairs, of King Street, Norwich, pleaded guilty at Barkingside Magistrates’ Court on 13 March to breaching reg 4(1) of the Work at Height Regulations 2005 and was also ordered to pay costs of £5,392.
HSE inspector Prentiss Clarke-Jones said after the hearing: “Roof work requires a high level of planning, and supervision should be in place to ensure it is carried out safely.
"This incident so easily could have been fatal; work at height is a well-documented, well-regulated risk and there is no excuse for getting it wrong.”