Alan Reay has apologised to the families of the CTV building's victims, saying the building did not meet his standards.

Reay, principal of the company that designed the CTV building, issued the apology during the Canterbury earthquakes royal commission today.

"This is a terrible tragedy. I really feel for those who have lost their loved ones. To the extent that I can, I have tried to provide the commission with assistance to understand the cause of this tragedy.

"I've spent my life working in engineering and have always tried to maintain the highest standards of the profession.

"I apologise to all the families affected as this building did not meet my standards."

One hundred and fifteen people died when the CTV building collapsed on February 22, 2011.

Reay last week told the hearing he was not involved in the CTV design work in anything more than a "benign" way.

The hearing earlier heard structural drawings submitted with the CTV building permit were unlikely to have been completed.

The commission heard that city council consents officer Graeme Tapper had written to Alan Reay Consultants in 1986 outlining a list of concerns in the application.

The lead engineer on the project, David Harding, told commissioners that the nature of Tapper's concerns suggested the drawings were not finished.

He had not seen the drawings, believed to have been prepared by draughtsman Wayne Strachan, before they were submitted to the council a month after the original permit application.

"The list Mr Tapper came back with had some items on it which Wayne wouldn't have missed,'' Harding said.

''If he had finished the drawings ... there wouldn't have been those things needing to be asked for. They would have been done." 

Strachan said in his evidence yesterday that there appeared to be a rush to submit the documents, but Harding could not recall it being hurried.

"No more so than any other building. Every building has a deadline on it and we're usually behind it. That's just the way it goes. There's usually a rush on it," he said.

NO RECORD OF GAS BOTTLE

The inquiry heard earlier that gas was unlikely to have caused a fire in the CTV building wreckage.

The fire that broke out after the collapse on February 22 last year hampered rescue efforts.

It had been believed the fire was started by a nine-kilogram gas cylinder inside the building. Exploding cars were another possible cause.

Christchurch City Council resource consents and building policy manager Steve McCarthy earlier told the Canterbury earthquakes royal commission that no permits had been issued.

However, certification for quantities under 100kg was not needed.

"There's no record of a dangerous-goods licence or hazardous-substances certificate in respect of gas bottles on that site," McCarthy said.

"There was a suggestion that it might be part of a cooler cabinet, but we asked our health people if they have any recollection or record of that. There's nothing on the file to suggest there was a 9kg bottle of LPG gas on that site."

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