The inexperienced designer behind the ill-fated CTV Building has defended himself against what his lawyer has described as being "a sustained attack" on him during an inquiry into the fatal collapse.

Structural engineer David Harding was given "sole responsibility" for coming up with the CTV Building plans by his boss at Christchurch design firm, Alan Reay Consultants Ltd.

The six-storey office block collapsed in last February's magnitude-6.3 earthquake, killing 115 people.

This week, as the lawyers make their closing submissions after the eight-week royal commission of inquiry hearing into the disaster, Mr Harding has been blamed repeatedly for errors in its design.


Design blunders by Mr Harding, and his boss Dr Alan Reay, were blamed as the "primary cause" for the collapse by counsel assisting the Canterbury Earthquakes Royal Commission, Stephen Mills QC during his closing submission earlier this week.

The hearing has heard evidence that Harding was inexperienced in designing multi-storey buildings, and with the company's complex computer modelling system.

Today, Mr Harding's lawyer Michael Kirkland made his final submissions to defend his client.

He said his client was part of a four-man team and it was wrong to blame him for the final design.

Mr Kirkland said Mr Harding was, and still is, "a competent engineer" who was left without "the resources and expertise upon which he could rely".

A 1991 report which identified design flaws should have been "a sufficient warning" for a detailed inspection of the building to be ordered by Dr Reay, the lawyer said.

Concluding his submissions, Mr Kirkland said that while his client was overseas, he had been asked to relay a message to the families who lost loved ones in the catastrophic collapse.

"There is never a day that goes by where I do not think about the CTV Building," Mr Harding said.

"Again, to the families of those who lost loved ones in the collapse, my thoughts are always with you."

He had apologised to the families when he gave evidence earlier in the hearing for what he described as a "worst-nightmare scenario".

His boss, Dr Reay, also apologised for the building which "did not meet my standards".

The hearing is due to conclude later today and the royal commission, chaired by Justice Mark Cooper, has until November 12 to produce its final report.