A meeting last month between councillors and consultants had "highlighted the potential shortcomings if council was to progress an option that only just gets over the 33 per cent building code requirement," the council staff report said.
Hastings Mayor Lawrence Yule said yesterday once the "preliminary design stage" work on the 70 to 75 and 100 per cent options was carried out, the council would be in a position to consult with the public on the "viable options" for the Opera House's future.
The 35 to 45 per cent fix was not considered viable because of the high number of people that would be using the building, he said.
Asked about the option of demolishing the iconic facility, Mr Yule said: "The feedback we're getting is that it must be preserved and I don't think anybody is seriously suggesting that it should be demolished."
Once it has more details on the required work, probably in three or four months, the council will carry out formal consultation with residents before making a final decision on the strengthening work, Mr Yule said.
The council has budgeted $20 million to spend on three projects over the next 10 years - $8.5 million for the Opera House, $7 million for the redevelopment of Clive Square and $4.5 million to develop a CBD hotel.
But given the Opera House strengthening costs had ballooned since estimates were made last year, the council would have to rejig its spending on the three projects following consultation with the public.