Allan Thomson of Bonnybridge, Stirlingshire and his company Building and Dismantling Contractors Ltd were also fined £400,000 and ordered to pay £55,000 court costs.
Building and Dismantling Contractors was subcontracted by main contractor C. Smith and Sons to demolish the Harvey’s and Carpetright buildings in Heaton Norris, Stockport in 2014.
Manchester Crown Court heard that a 47-year-old man sustained life-changing injuries and 42-year-old Scott Harrower died during the work.
Michael Smith of Rochdale and his company C. Smith and Sons (Rochdale) Ltd, were found guilty of safety offences.
Smith was jailed for eight months, fined £90,000 and ordered to pay £45,000 court costs.
The court heard it was originally planned that machinery would be used to remotely bring down the structure – a method that would have entailed minimum risk to those workmen tasked with the demolition.
But between winning the contract and the work actually being carried out, the decision was taken by Smith that the building should instead be dismantled piece by piece, meaning workmen would be required to work at height to remove the roof sheets prior to the structure being unbolted.
C. Smith and Sons then subcontracted the job of demolishing the roof to Building and Dismantling Contractors.
The roof of the building was made up of steel corrugated sheets with interspersed plastic skylights, which had deteriorated over time and had subsequently been covered with corrugated steel sheets in a bid to repair the damage.
On 20 January 2014 Harrower accidentally stepped through a skylight and nearly fell the 30 feet to the concrete floor below.
On that occasion he managed to prevent himself from falling, but the near miss did not prevent the men from returning to carry out their work the next day.
At just after 9am on Tuesday 21 January 2014, one of the group – a 47-year-old man – fell through a skylight to the concrete floor below, fracturing his spine, pelvis, right leg, heel and wrist.
Despite their colleague suffering horrific injuries, the men were ordered to return to the roof just hours later and at 4pm Harrower fell through a skylight to the concrete below.
He suffered catastrophic head injuries and died as a result.
Detective Chief Inspector Richard Eales said: “First and foremost, our condolences go to the families of Scott and his colleague, who were the victims of both companies’ criminal negligence and who died in tragically preventable circumstances.
“It is clear from the evidence that both Smith and Thomson saw an opportunity to make a quick profit without any thought for the workers they sent on to the roof, and as a direct result of that greed Scott died and another man suffered life-changing injuries.
“Smith and Thomson’s remorse did not then stretch to admitting their guilt, as both tried to hide behind their companies and refused to plead guilty to the charges levelled against them personally.
“Thankfully, the jury saw through their attempts and both now can face justice for the decisions that they made, decisions that have robbed one family of a loving partner, father, and son, and another of a man’s ability to live a life untainted by severe physical injury.”