An earthquake engineering expert says he disagrees with parts of a critical report he approved on the fatal collapse of the Canterbury Television building.
The Canterbury Earthquakes Royal Commission is investigating why the building failed in the 6.3-magnitude quake on 22 February, killing 115 people.
Nigel Priestley told the inquiry on Wednesday he personally disagrees with the way its earthquake performance was analysed.
Professor Priestley, a member of the panel that signed off the document, disputed the way calculations were made regarding deficiencies in the building's design, the failure of its columns and its geometry.
He says a technique called non-linear analysis would have produced more accurate results, but was halted in favour of another method.
He did, however, agree with the general conclusion that the building did not meet the design standards of the day when it was built in 1986.
Professor Priestley said the report should have placed more significance on the failure of the building's interior columns.
"The interior columns were significantly more vulnerable to failure than the exterior columns, particularly when the effects of the recorded high vertical accelerations are considered. This conclusion differs from that in the CTV report."
On Tuesday another panel member Rob Jury told the commission that the report was worded carefully in order to best account for engineers' differing opinions.
Meanwhile, a structural engineer rejected suggestions the Canterbury Television building should have been red stickered after the 7.1-magnitude quake in September 2010 because of its age and increased movement during aftershocks.
The suggestions by American engineer John Mander are expected to be heard in full when he gives evidence on Thursday afternoon.
On Wednesday some of his views were put to William Holmes, another structural engineer from the United States, who peer reviewed a critical report on the CTV building.
They were that the building should have been deemed unfit to occupy after the September quake because, at 25 years, it was too old and the floor became more lively during aftershocks.
Mr Holmes told the commission this reasoning is impractical and goes against rules the engineering profession has used for a long time.