Commission officials inquiring into the collapse of the CTV building in Christchurch have heard a shortage of structural engineers meant it never got a thorough assessment.
Witnesses from rapid assessment teams gave evidence on the fourth day of the eight-week Canterbury Earthquakes Royal Commission of Inquiry on Thursday.
Failure of the CTV building killed 115 people when it collapsed in a 6.3 magnitude earthquake on 22 February 2011.
Building inspectors who carried out rapid assessments on the CTV building following the 7.1 magnitude earthquake in Canterbury in September 2010 gave it a Level 1 inspection - which just meant an outside observation - before giving it the green sticker.
It was eventually given a second check by a team led by a city council building Inspector, David Flewellen.
He says it was out of the ordinary to conduct Level 2 assessments without an engineer but his manager told him they had no choice.
Mr Flewellen said that, in hindsight, the assessment teams were insufficiently trained.
Another member of a rapid assessment team told the inquiry it did not think there was enough damage to the building after the September 2010 earthquake to warrant a second inspection.
Christchurch City Council building inspector Peter Van der Zee and other assessors checked the building following the 7.1 magnitude quake of September 2010.
Mr Van der Zee says the team stood outside in a carpark and looked for obvious damage like broken glass or cracks, as the rapid assessment criteria required. They gave the building a green sticker.
Mr Van der Zee said they did not enter the building after giving it a Level 1 inspection.
He said he had only a vague recollection of inspecting the building.
In response to questioning from Crown prosecutor Mark Zarifeh, he told the inquiry he did not receive any training in inspecting quake-affected buildings.
Mr Van der Zee asked not to be filmed while giving his version of events but the request was declined by the commissioners.
Teams 'followed procedure'
Building surveyor Graham Calvert, who volunteered to help rapid assessment teams working for the city council, said it was not a requirement at the time to have an engineer in the team.
Mr Calvert said it was standard procedure to carry out a visual observation and then advise building owners and tenants to seek their own engineering inspection.
He said he was not aware any building higher than four storeys automatically required a Level 2, or internal, inspection.
A lawyer for bereaved families asked Mr Calvert for the rationale behind giving the building a green sticker.
Mr Calvert said his team felt the building didn't provide any immediate danger to occupants at the time.
He said the team did the best they could on that day and would not have issued the green placard if they felt the building wasn't safe.
Concrete in CTV building 'brittle'
The commission has been told that concrete used in the construction of the CTV building had similar qualities to chalk.
Forensic structural engineer Rob Heywood, who inspected the building 30 hours after it collapsed, gave evidence on Wednesday.
He told the commission he noticed something peculiar about the concrete being taken from the scene as the search for bodies and survivors took place, and said it would disintegrate whenever diggers tried to move it.
"Many people at the building site noted how readily the concrete turned to rubble," he said.
"It was surprisingly difficult for a machine to lift any substantial piece of concrete without it breaking."
Mr Heywood described the concrete used in the beams and columns as having similar properties to chalk and said that, like chalk, the structures would have given no warning signs they were about to give way.
He said brittle concrete of this type would fail to give a building the ductility or flexibility it would need to allow it to remain standing in an earthquake.