An expert panel has been debating the code compliance of the Canterbury Television building which collapsed during the February 2011 earthquake, killing 115 people.
The discussion is being held before the Canterbury Earthquakes Royal Commission, which is investigating the building's failure.
The seven experts include an engineer who worked on the CTV building and the authors of a critical government report into the building's design and construction.
While some experts identified issues with the code, others said calling them errors would be too black and white and the code's interpretation would always depend on the skill of the engineer.
Commissioner Mark Cooper said a code could never be written like a statute and it was not possible to achieve complete precision.
But he said the answer might be that designers of certain buildings where failure could be serious should have extra qualifications.
On Monday, structural engineer Murray Jacobs told the commission that drag bars, which were added in the early 1990s, could have reduced the strength of the walls.
Dr Jacobs says drilling into already-set concrete can make the structure weaker.
He says the drag bars, which help evenly distribute earthquake stress, should have been part of the building's original construction in 1986.