The lawyer for the man whose company designed the CTV building says it was the strength and number of Canterbury earthquakes that caused its collapse - not any design faults.
The Canterbury Earthquakes Royal Commission is looking at why the Canterbury Television building in central Christchurch collapsed in the 6.3-magnitude quake in February 2011, killing 115 people.
In closing submissions on Thursday, Hugh Rennie, QC, spoke on behalf of Alan Reay, whose company Alan Reay Consultants designed the building.
The lawyer assisting the Royal Commission, Steven Mills, QC, argued that Dr Reay's attempts to shift the responsibility of the building's failings to others was disingenuous.
"Of course the earthquake itself is the trigger at one level, but the building had significant design defects which that earthquake found. That is why this building collapsed as it did, when others did not."
Mr Mills said design faults made the building more it vulnerable in the quake on 22 February. But Hugh Rennie disagreed with that, telling the inquiry that a number of other factors were to blame.
"We've had a lot focus on what was needed to be done to get a well-designed and constructed building, but that's the beginning of the responsibility of the building which then becomes a management and maintenance responsibility.
"We will never know if this building had been managed in a different way whether it would have been occupied on the 22nd of February or not."
Mr Rennie said that the building should have been red-stickered after the first big quake to hit the region, a 7.1-magnitude quake on 4 September 2010.
"But after that it was not perceived that that survival was a point at which the building was not safe to further use."
Hugh Rennie also said Mr Mills is focusing on evidence that was often "second and third-hand trivialities that may or may not have happened".
He pointed out that the emphasis the inquiry had placed on structural engineer David Harding's lack of experience and credibility was a "mysterious error".
"It was, therefore, a striking contrast and a mystery in respect of Mr Harding's CTV design work. No issue whatsoever has been identified with any work Mr Harding did in any part of his career as an engineer before the CTV work or in the 26 years that followed."
The final submissions in the two-month inquiry into the building's collapse will be made on Friday.