Witness reports that the Canterbury Television building was "livelier" after the Boxing Day 2010 earthquake "fell on deaf ears", an engineer says.

John Mander, a former University of Canterbury engineer now based in the United States, told the Canterbury earthquakes royal commission today that concerns about movement voiced by CTV occupants before the disastrous collapse on February 22, 2011, should have been heeded.

"The human body is a wonderful motion sensor," he said.

"Although it may not be possible to accurately predict the magnitude ... it is very capable of understanding relative differences - this one is bigger than that one.''

Survivors of the collapse, which killed 115 people, reported extra "bounciness" in the building after the Boxing Day 2010 aftershock.

Mander acknowledged that nerves and heightened awareness after a major quake meant people were more sensitive to such movement, but their concerns were real.

"These [concerns] served to provide additional evidence and it should have rung alarm bells, but apparently these alarm bells that people were raising fell on deaf ears and nothing was done about it."

Earlier, Mander said cumulative damage from the September 4, 2010, quake onwards meant the building's seismic capacity on February 22, 2011, was lowered.

"What was happening was that the response was eating into these reserve capacities ... and that was the sign of these initial damages that were shown up."

Design faults over the building's eccentric layout may have exacerbated this, he said.

Commissioner Richard Fenwick said a CTV-type building would not meet today's building standards, but others like it did not collapse.

"That type of building is no longer permitted, and that's quite right too, but of course there are quite a few buildings in Christchurch of that type which survived and performed well," he said.

"Maybe that's the reason that they did," Mander replied, "because those other extraneous faults [were not there]."

A 1990 report by engineering firm Holmes Consulting Group found the building may not be code-compliant.

Drag bars were installed on the top three levels to strengthen connections between the floor slabs and the north shear wall, allowing for greater stability in an earthquake.

Evidence will conclude tomorrow.

- © Fairfax NZ News