Families of CTV building victims brace for further testimony

Emergency services searched the rumble for survivors of the collapsed CTV building for days after the fatal quake. Photo / Brett Phibbs

Families of the 115 people killed in the February 22 collapse of the CTV building are bracing themselves for the third week of the royal commission hearing into the disaster which resumes on Monday.

The joint authors of the Department of Building and Housing (DBH) report into the collapse, which identified three "critical factors" in its failure - brittle columns, intense ground shaking, and the asymmetrical layout of shear walls - will continue to give their evidence on Monday.

The DBH report also found that concrete in many of the six-storey Christchurch building's columns were significantly weaker than it should have been.

The Canterbury Earthquakes Royal Commission heard this week from a contractor who claimed he drilled up to 200 holes into the beams of the CTV building in the late 90s, though admitted his memory was "hazy".

Daniel Morris was company director of Christchurch firm Knock Out Concrete Cutters when it got the job to drill holes "all over the place" in the concrete beams and floors of the doomed city office tower between 1995 and 2000.

But he can't remember who commissioned the work and has no records to firm up his story, which he told the commission on Thursday.

Also scheduled to give evidence next week are two experts who peer reviewed the DBH report on behalf of the royal commission, William Holmes and Professor Nigel Priestly.

But perhaps the most anticipated witness of the week for bereaved families will appear on Thursday.

Dr Alan Reay, whose firm Alan Reay Consultants designed the building in the mid-1980s, will give his version of how it came to be designed.

The commission hearing - due to last eight weeks - is looking at how the concrete building failed so catastrophically when the magnitude-6.3 shake struck at 12.51pm on February 22, 2011, killing 115 people.

It will report on the causes of building failure as a result of the earthquakes as well as the legal and best-practice requirements for buildings in New Zealand Central Business Districts.

The commission will also look at the permit process, the design and construction phases, a close examination of the code compliance, remedial measures carried out after faults were found in 1990, and the assessment process which started on the building after the September 4, 2010 quake.

It has until November 12 to deliver its final report.