Tauranga City Council has launched an investigation into their building inspection staff following the Bella Vista Homes development.

Mayor Greg Brownless confirmed retired judge Graeme Colgan will head the investigation aimed to identify "hard truths" around council failings in their building consent authority capacity.

Council is already being investigated by the Ministry of Business, Innovation and Employment over the Bella Vista Homes debacle which left 21 homeowners evacuated after shoddy workmanship was discovered, despite homes passing council inspections.

Four properties had full code compliance certificate and were then deemed dangerous.

Four months since councillors voted, in principle, to purchase the affected homes 20 are still in negotiations with legal threats looming.

Greg says council had to face the issue head-on.

"There were some unanswered questions in finding out the why," he said. "We know the how."

"The new chief executive had commenced an employment investigation into staff involved from our end."

A big fear for council still counting the costs involved in the saga is a repeat of the same events again.

"The most important thing is that this never occurs again," says Greg.

"For me, I want to know that area [building] is well run and we're doing the things we are supposed to be doing."

Terms of reference for the investigation were not available but Greg says the report, minus any employment issues will likely be made public upon completion.

"We hope to have it finished by the end of the year."

-Stuff/Matt Shand