The CTV building collapsed and killed 115 people because of faulty design, the Canterbury Earthquakes Royal Commission has been told.
The commission is in its final days of hearing submissions on why the building catastrophically failed in the February 2011 earthquake.
Commission lawyer Stephen Mills said evidence presented during the eight-week hearing gave a clear picture about what caused the building to pancake.
He said the primary cause of its collapse was mistakes in its design.
Mr Mills said structural engineer David Harding had little experience in designing multi-storey buildings and his employer at Alan Reay Consultants, Alan Reay, was also responsible for the collapse because he handed the design work to Mr Harding, who was not competent to handle the job.
"The decisions that they made about the structural design of the building are, in my submission, the primary cause of the building's collapse," Mr Mills said.
"In critical respects, the building they designed was not code compliant and was dangerously vulnerable to any earthquake that took the building any distance beyond its elastic response state."
Mr Mills said there was either no margin of safety or an inadequate margin.
The exact trigger of the collapse was not clear he said.
The Christchurch City Council had to also take some blame, he said, because it had signed off the plans for the building even though it did not comply with the building code or its own by-law.
The final submission on Thursday will be from a lawyer acting for the people injured in the collapse and for the families of those killed.
The commission's final report must be produced by November 12.