A structural engineer has broken down and admitted responsibility for a design flaw that led to a building panel falling and killing a woman in last February's earthquake.

Dick Cusiel of LSC Consulting today gave evidence at the Canterbury earthquakes royal commission hearing into the building at 43 Lichfield St.

The building, known as the Anderson building, was one of four comprising Ballantynes department store.

STACY SQUIRES/Fairfax NZ GIVING EVIDENCE: Dick Cusiel of LSC Consulting gives evidence at the Canterbury earthquakes royal commission hearing today.

Cusiel led LSC Consulting's design of the building.

At 12.51pm on February 22 last year Linda Arnold, 57, was sitting in her car outside the building when she was hit by a falling concrete panel and killed.

Cusiel told the commission the concrete panel, known as a spandrel, was attached to the exterior of the building's upper storey car park, but was not connected properly.

"It is, regrettably, this omission which in my view has contributed, with the significant force of the earthquake, to the spandrel falling away from the structure."

The design was drawn by another LSC staff member, but Cusiel missed the error and signed off on it as part of the building consent application.

Cusiel broke down as he "absolutely" accepted responsibility for the mistake.

"Having sent the consent for the drawings and noted the omission, [Linda Arnold's death] has weighed very heavily on me and will always. I extend my very sincere condolences to the family of the victims for this extreme tragedy."

The spandrels on the building's Lichfield St side were attached by a concrete insert known as a TCM-20, Cusiel said, but should also have had pre-cast steel ties to the floor topping, as on other parts of the building.

"The panels were affixed with weld plates and angle cleats to the columns. However, they are primarily there for the purpose of construction, to put the panels in place while the floor topping was poured.

"They were unlikely to have been sufficient to keep the panels in place in the event of a major earthquake."

Cusiel did not know anyone had died because of the falling concrete panel until he was contacted by the commission in November last year.

In acknowledging his mistake, he said the oversight should have picked by Christchurch City Council (CCC) staff assessing the drawings included in the building consent application.

"The council would inspect the drawings, pick up any anomalies and refer them back to the engineer to discuss or change."

He was challenged by council lawyer Duncan Laing that the omission was not so obvious it should have been picked up by council staff.

"If the council had inspected they almost certainly would have said 'There's something amiss'.

"I'm not trying to blame the council. I have accepted full responsibility for this. There's no need to hammer the point really."

Christchurch City Council environmental policy and approvals manager Steve McCarthy and structural engineer Peter Smith of Spencer Holmes will give evidence to the commission this afternoon.

STRUCTURAL DAMAGE 'NOT OF CONCERN'

Damage to the car-park building was "not of structural concern", the commission heard earlier today.

The building was inspected after the September and Boxing Day 2010 quakes and issued a green placard.



Powell Fenwick engineer Hannah Clarke told the commission she inspected the building twice after the September quake, but only in places specified by Ballantynes property manager, Paul O'Connell.



"I was looking at specific areas that Mr O'Connell was interested in. There was some reference made to the original design engineers conducting some inspections. Given the lack of damage at that time there wasn't anything that made me believe I should be inspecting those areas."



Clarke said she inspected only the basement and two retail floors of the seven-storey building, and did not examine the car park, where the concrete panel that killed Arnold fell from.



The inspection was enough to confirm the building was not in danger of structural collapse, she said.



"I was not asked to and I did not inspect the exterior of the Anderson Building fronting onto Lichfield St on either of inspections prior to February 2011."



Ballantynes managing director Mary Devine said the company assumed the inspection would consider the structural integrity of the Anderson building "as a whole".



"We believe there wasn't specific instruction provided. The recollection of our property manager was we were looking at the structural integrity of the building as a whole. We did not specifically highlight the car-park building to be addressed."



Engineering firm LSC consulting was engaged to look at the car-park building, Devine said, as the company was involved in its design.



"It was felt at the time to get them involved because they were involved with the original construction. We probably leaned on their interpretation of what happened on the car-park levels."



The building was constructed in 2002.