The Christchurch City Council engineer who signed off the design of the CTV building in 1986 believed it was an earthquake risk but came under pressure to sign the plans, his widow has said.
Graeme Tapper was never happy with the building, Pat Tapper told the Canterbury Earthquakes Royal Commission hearing into the collapse of the building which claimed 115 lives in the February 2011 earthquake.
"His view was it was an earthquake risk. It was not a question of if, but when," Mrs Tapper said on Thursday.
But he felt he would be sacked if he didn't sign after coming under pressure from his boss, the late Bryan Bluck.
Structural engineer John Henry, who worked with Mr Tapper and Mr Bluck at the council in the 1990s, told the royal commission that Mr Tapper regularly questioned the design of buildings by Alan Reay Consultants, where Mr Henry also worked, in the mid-1980s.
Mr Henry said Mr Reay would often go above Mr Tapper's head to Mr Bluck to get building consents.
Mr Tapper and Mr Bluck would have arguments but Mr Tapper was "ultimately over-ruled" by Mr Bluck, Fairfax Media reported.
Mr Henry also told the royal commission he was concerned to learn that his calculations for Landsborough House in Christchurch, when he worked for Alan Reay, were used as a template for the CTV design.
He said his calculations would be clear only to an experienced designer, but the engineer who used them had not worked on a high rise before.
Using models, Mr Henry showed the commission how the two buildings were constructed differently and how the CTV design left it vulnerable to an earthquake.
Landsborough House stood up in the February 2011 quake, but is listed for demolition.