Non-complying features in the Canterbury Television (CTV) building would have been difficult to find in council engineering checks, an inquiry has heard.

Structural engineer Arthur O'Leary today told the Canterbury earthquakes royal commission that the building was non-compliant at the time it was permitted.

Some internal beams, beam-column joints and the north-wall connection did not meet the code, he said.

The faults would have been "difficult to pick up", although an experienced reviewing engineer may have found them.

O'Leary said the south sheer wall may have separated from the floor slab earlier in the collapse sequence than expected.

Willie Palmer, the lawyer for building designer Alan Reay Consultants, asked if that was likely to have occurred before column failure.

"It would not surprise me," O'Leary said.

Today's evidence is focused on code compliance.

Structural engineers Douglas Latham and John O'Loughlin will also give evidence, and an expert panel will discuss elastic response spectra analysis.

More than 80 witnesses will be called during the eight-week hearing, which will cover the initial building consent issued by the Christchurch City Council, the construction and design, identification of a structural weakness in 1990, and the assessment after the September 4 and Boxing Day quakes in 2010.

The hearing was expected to finish this week, but was likely to continue next week because of time lost during the proceedings.

The commission has until November 12 to complete its work.

- © Fairfax NZ News