Mr Thew said throughout the process advice on the opera house was worked through as were technical opinions views, all of which came back to two key parts of the Building Act 2004. "Part A being that the percentage of a new building standard was lower than 34 per cent," he said.
"However, the key part of the Act was Part B, was where the assessment of the engineers is the consequence of a failure would likely see injury or death either to an occupant or someone outside that building. All the reports confirmed Part B."
He said from this HDC sought legal advice as both a building owner and secondly as a building regulator.
"It is also important to note that in the case of the Municipal Building and the Opera House they are tested with an earthquake ... twice the size of a normal building due to the level of occupancy," he said. "Anything over 300 people in a building, the tests for an earthquake is basically doubled."
Moreover, he said if the rebuild comes in at the engineering fraternity's preferred option of 67 per cent, it would be damaged to the point where people could get out safely but it would suffer damage and require significant remedial work.
Mr Thew said also earlier this year councillors at the workshop gave the direction not to design for a building-safe approach. "In that I mean building in a structural capacity to allow the building to stand and be fully functional post an event," he said. "The price order of that design would add us well into excess of $34 million just for the theatre." He did warn about how numbers were used in this process.
"We just have to be careful of how we play with numbers because they don't always fit the situation," he said.
"Council is also aware there isn't a decision to simply carry on with a theatre rebuild, carry on with the municipal [building]. The IWP are working through options that Council are scheduled to see in December around whether putting back what we have got, or doing something different is the most appropriate approach."