The Canterbury Television building's "pioneering" design may have been beyond the expertise of council staff reviewing the plans, an inquiry has heard.

John O'Loughlin, an experienced structural engineering peer-reviewer, today told the Canterbury earthquakes royal commission non-code compliance in the CTV building's column should have been found by council's reviewing engineers.

However, the "pioneering" design would have made it difficult to pick up other some non-compliant elements.

"It would have stretched the capacity of the council staff to fully understand how that building was working," he said.

It was unlikely Graeme Tapper, the council officer who approved the design, had colleagues with the necessary expertise to discuss the plans, O'Loughlin said.

"If that became an issue for a peer review in consulting office, there would be two, perhaps three engineers who would discuss it among themselves. [Tapper] didn't have that advantage," he said.

The commission has heard evidence that the building's principal designer, David Harding, had limited experience with multi-level design and his employer, Alan Reay, did not check the plans.

Counsel assisting the commission Stephen Mills asked O'Leary if, in his experience, it was appropriate that an engineer without experience in multi-level design be left to work unsupervised.

"No, it wouldn't be appropriate," O'Loughlin said.

The inquiry heard earlier suggestions the building may have been code-compliant were "opportunistic".

Douglas Latham, an engineer employed by building designer Alan Reay Consultants, said the building's columns could be interpreted as code compliant using an "alternative set of assumptions".

Panel member Barry Davidson, a structural engineer, said Latham was interpreting clauses in the code in a "very legalistic, opportunistic way".

"It can't be done that way and I think we should start just accepting that ... You must understand engineering rules of nature," he said.

Davidson had become "quite frustrated" with code interpretations and an inference that engineers of the time were less knowledgeable.

"It seemed to come from the legal professional that this is a legal document, and maybe it is, but it has to be interpreted by a competent engineer."

Engineers in 1986 were "equally competent", he said.

"I think the knowledge of behaviour of shear walls, etc, wouldn't be far short of where it is today."

Building codes would never be perfect, Davidson said.

They would always require "good interpretation by knowledgeable people".

"If we want to cherry-pick our way through it and find errors in this code, we'll be going forever, and when we do it, we'll still fall short," Davidson said.

"I'm not too keen to support that this was an error in the code. I think it allowed ill-informed people to interpret it incorrectly."

Panel member Arthur O'Leary said blaming errors in the code was "seeing things in a very black and white way".

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