The construction manager for the company that built the Canterbury Television (CTV) building has changed his mind and will give evidence to the Canterbury Earthquakes Royal Commission.

Gerald Shirtcliff, 67, now living in Australia, had initially declined a request to give evidence to the hearing looking into the collapse of the building during last year's February 22 earthquake, which killed 115 people.

He was a construction manager who worked for Williams Construction, which built the CTV building in 1986-87.

However, on Thursday the commission said Mr Shirtcliff had provided a signed statement of evidence and agreed to appear before the commission via videolink, The Press reports.

Mr Shirtcliff was convicted of fraud in 2005 and jailed for 20 months after he convinced a Queenstown investor to buy his virtually useless vehicle-servicing concern for $296,500, the paper said.

He now lives in Brisbane under a different name - William Fischer.

Mr Shirtcliff is expected to give his evidence when the hearing looks at the building's construct in the week starting July 30.

Earlier in the day Christchurch City Council building inspectors were grilled about their assessment of the CTV building after the city's first big earthquake, in September 2010.

Russell Simson, Graeme Calvert and Dave Flewellen were in the team of building inspectors who carried out rapid "level-two" assessments after the first quake.

This required visual assessments of obvious damage inside and outside buildings.

They all emphasised that they were not engineers and had never claimed to possess such expertise.

They placed a green sticker on the CTV building, which meant the owner did not need an engineer's assessment before the building could be re-occupied.

Mr Calvert said he was unsure of the criteria for level-two assessments.

When asked during cross-examination if he should have ticked a box in a form that stated further engineering inspection was required, Mr Calvert replied that in hindsight he should have.

An email from a CTV manager, Murray Wood - who subsequently died when the quake destroyed the building - to all staff assured them that only superficial damage had been found by "three engineers".