An engineer who looked at the CTV building when it was being built has told a Royal Commission he thought at first its structural elements were inadequate.
But he said he was assured due diligence had been done.
The Canterbury Earthquakes Royal Commission is investigating why the six-storey building collapsed in the February 2011 earthquake, killing 115 people.
The commission has already heard that a council engineer, Graeme Tapper, felt pressured by his boss, Bryan Bluck, to sign off on plans for the building.
On Monday, a former council engineer Peter Nichols said he viewed the building, designed by Alan Reay Consultants, when it was under construction and thought it lacked structural elements.
Mr Nichols said he queried this with the council's chief engineer, Mr Bluck, who told him he had initially shared his concerns but had done due diligence and been persuaded by Dr Reay that the concerns were unfounded.
A draughtsman employed by Alan Reay Consultants told the commission that his boss sometimes went over the head of a council engineer who wanted more detail on projects.
Terry Horn said it was Dr Reay's practice to go over Mr Tapper's head and speak to Mr Bluck.
'No memory' of working on CTV building design
Earlier Mr Horn told the hearing he could remember many of the projects he had worked on during his time with Alan Reay Consultants but not the CTV building.
Mr Horn said timesheets indicated he had spent about 140 hours doing draught work on the building but he disputed that - although he said it was possible he could have detailed some foundation reinforcing.
He also said it was not unusual for the work to be split up between draughtsmen if timeframes were tight.
Mr Horn told the commission he had no idea his firm had designed the building.
