A roofing contractor has been ordered to pay more than £6,000 in fines and costs following the incident in August of last year.
And health and safety officials have said the worker could have been killed or permanently disabled in the incident.
Leighton Johnson, whom court papers showed as trading under the name of Eastern Roofing, pleaded guilty to two counts of breaching health and safety regulations during a hearing on Wednesday.
Documents said he had not ensured the safety of his employee, named as Joe Wones, by failing to properly plan or supervise the work at the site in Rollesby Road.
He also failed to ensure that there were sufficient platforms, coverings, guard rails or other supports in place while the work on a fragile asbestos roof was being completed.
Mr Wones, 26, fell seven metres, almost 23 feet through the roof, landing on a palette.
He suffered injuries to his back and sternum and had to wear a full body brace for six weeks after the incident.
A Health and Safety Executive (HSE) investigation revealed no fall prevention or fall mitigation system in place and that Mr Wones had not been wearing any safety equipment at the time of the incident.
They said there had also been a lack of any health and safety management or planning for the job and no adequate training or safety equipment had been provided.
Magistrates fined Johnson, of Hare Close, Mulbarton, a total of £3,000 and ordered him to pay a further £3,415 in costs, plus a £300 victim surcharge.
Following the case, HSE inspector Paul Unwin, who investigated the incident, said: “This incident caused serious injuries that could have cost a young man his life or prevented him from being able to walk again.
“The risks of working on fragile roofs are well-known but so too are the ways to manage those risks.
“Sadly, HSE inspectors too often find blatant disregard of easily-accessible guidance, which frequently results in life-changing injuries.
“Work on fragile roofs must be correctly planned and managed to ensure the safety of all involved.
“The inadequate and unsafe way in which this job was carried out highlights the risks of working at height and how important it is to do it safely right from the start.”