A report outlining concerns about construction standards at the Canterbury Television (CTV) building did not raise any "red flags" about its overall design, an engineer for the building designer says.

Alan Reay Consultants (ARCL) engineer Geoff Banks this morning told the Canterbury earthquake royal commission he relied on the expertise of the company which produced the report when deciding not to check for other problems.

The Holmes Consulting Group inspected the building for a potential buyer in 1990, and found that connections between the building's floors and key support wall were not strong enough.

Banks said the problem meant the building would "effectively separate" from the shear walls before they reached their full loading capacity.

He had relied on Holmes' "excellent reputation and particular expertise with multi-level buildings" when deciding to focus on the one issue it had raised.

"There was nothing in the Holmes report which caused me to question the conclusions it had reached," he said.

"There was nothing that alerted me to any red flags about the overall design."

Banks said he was involved in discussions about the necessary repairs until February 1990, before a "blank period" without progress until early 1991.

"I'm not sure why there was a blank period or why the process stopped; I could speculate, but I don't know."

ARC did not have "significant concerns" about the building, as it was vacant and was not considered earthquake-prone by the standards of the day, but decided the work should be done before the building was occupied.

The building was eventually strengthened in October 1991, before a new tenant moved in.

- © Fairfax NZ News