Justice and Courts Minister Amy Adams released a statement on Wednesday explaining some of the findings of a draft business plan on the building's required strengthening.
That plan showed strengthening costs would be more than $15 million, she said.
The ''magnitude and cost'' of the plan meant ''Cabinet rules'' kicked in, forcing a Treasury assessment process before the plan could be approved by Cabinet.
That would take ''a number of months to complete''.
Mrs Adams' office yesterday did not respond to an Otago Daily Times question on how many months that might be.
The reaction from Dunedin construction and engineering experts was unequivocal yesterday.
Dunedin structural engineer Stephen Macknight called the Government's $15million strengthening figure ''absolutely ridiculous''.
He had been involved in the earthquake strengthening of about 50 Dunedin buildings in his career, he said, and none had come close to that price tag.
The ADInstruments building in Vogel St was a ''huge building'' and had required ''a couple of million'' for its earthquake strengthening, Mr Macknight said.
''It's way over the top with anything we've ever been involved in.''
Mr Macknight said the Government's ''reluctance'' to release details of what the figure involved ''makes you think there's a lot more there than just strengthening''.
''In the buildings I've done, you might have done 20 buildings for that sort of figure.''
Dunedin historic building owner Lawrie Forbes said there were always different ways of tackling engineering problems, and engineers had to find ''smart, innovative ways'' to achieve their goals within reasonable budgets.
''We don't have massive amounts of money to spend, so therefore we can't be foolish with it. This is Dunedin. It's not bloody Las Vegas.''
Lou Robinson, director of Hadley Robinson Engineering, said he knew the courthouse intimately after being involved in the 2002 work on the complex.
He estimated an ''upper limit on strengthening of perhaps $3million''.
''A budget of $5million would be generous.''
Professional and consent fees and costs of ''decanting while the work is being undertaken'' would be additional, he said, but the figures quoted in the draft business plan might include more than pure strengthening.
Dunedin City Council urban design team leader Dr Glen Hazelton said the combined earthquake strengthening done to date in Vogel St ''would struggle to come to $15million''.
The Government required owners of earthquake prone buildings to strengthen them, but the courthouse's cost could convince those owners the buildings were not worth keeping.
''The Government's putting up this massive figure, and other building owners will be saying `oh my gosh, we'll never be able to spend that much on our building'.
''It's just going to make everyone think they have to knock everything down.''
The courthouse's category 1 listing could not be used as a reason for such a high cost, he said.
''The protection afforded by the council's district plan only applies to the outside of the building.''
While the council would advocate that work be ''sensitive'' to the building's interior, ''they do have quite a lot of freedom inside''.
Director of Dunedin construction company Lund South, Russell Lund, said his experience suggested the $15million figure was ''just not even credible''.
''There's no way in the whole wide world that it could be that sort of figure.''
He cited a Christchurch building he had earthquake strengthened recently. It had sunk 350mm due to liquefaction, needed its floors ripped out and replaced, required some 70 piles to be added and a new perimeter foundation system built.
That ''incredibly complex'' job ''didn't even get to $2million''.
His Loan and Mercantile Building in Dunedin was bigger than the courthouse, sat entirely on reclaimed land and had external ornamentation similar to the courthouse's. Yet that building was expected to cost ''less than $300,000'' to earthquake strengthen, he said.
''There's always a gold plated way of doing something, and there's always the workable economic option.
''And Dunedin's got some engineers who are very good at providing workable economic solutions.''
