Danny Hough, 23, was crushed to death when two tonnes of masonry landed on top of him as he carried out work at a house in Batley.
Self employed builder Nigel Parker, 56, was given a two-year sentence after pleading guilty to manslaughter over the incident which took place at a family home on Thorncliffe Estate, Batley, on July 25, 2013.
Leeds Crown Court heard Mr Hough had been recruited to work on the day of the tragedy as Parker was desperately short of people to work for him.
Mr Hough, who had no building qualifications or experience in the industry, was tasked with demolishing the chimney with an electric hammer drill.
Jailing Parker, of Trentham Grove, Beeston, Mr Justice McDuff said: “What you did is almost unbelievable. It goes beyond competence, carelessness and thoughtlessness.
He added: “You will always have to live with the knowledge that you were responsible for this unlawful killing.”
The court heard Mr Hough was working in the bedroom and had been placed in the “gravest possible danger”.
Shortly before the chimney gave way, Mr Hough had sent a text to his girlfriend saying how much he was enjoying the work.
Alistair MacDonald, QC, said members of the family who lived at the property were also place at risk as they were at home at the time.
Parker, who also pleaded guilty to two health and safety offences, had left 45 minutes before the incident to go look at another property he was due to do work on.
Mr MacDonald said Parker failed to carry out a risk assessment and had not obtained an structural report.
He had also failed to put safety measures such as support props in place.
Mr MacDonald said: “It is the Crown’s case that to start demolishing this chimney without supporting the upper part of the chimney would place anyone near that work in the gravest possible danger.”
Lisa Roberts, mitigating, said Parker had suffered a mental breakdown from the strain of what had happened and had received treatment in a psychiatric unit.
She said not a day had gone by since the incident that Parker did not think about Mr Hough and his family.
Ms Roberts said the father-of-two was a sole trader and had worked hard in the building trade since leaving school at 16.