"The fundraising has been incredibly successful. Prior to this increase, the ratepayer commitment was $5 million."
He said even if the council has to pay all of the $9.4million shortfall, it was still worth it.
But Vinsen did say he was confident the council's fundraising team would be able to find half of the $9.4million increase to the Sarjeant's redevelopment.
Councillor Helen Craig said future-proofing and earthquake-strengthening heritage buildings like the Sarjeant were always difficult.
"They keep finding more issues than you can reasonably have expected so that's costing more [and] then it's the impact of Covid and what it's had on all prices and delays."
She said she understood the old Sarjeant building had less foundation work than was initially thought and so more bracing was a big extra cost.
"Nobody knew Covid was coming, nobody knew what the impact of that would be. And now you've got the fuel prices on top. So one thing after another."
She expected the council's fundraisers to go to Lotteries (which has already paid $6.8million towards the redevelopment) because of its significant heritage fund.
"You can't leave a building partly finished. The reality is we will have to pay what we will have to pay."
But, councillor Philippa Baker-Hogan said, she was disappointed in the nearly $10 million increase in capital cost.
She said Covid-19 and supply chain problems were not new and the redevelopment had significant resources, including its own advisory committee and a project director.
Baker-Hogan raised the concern the "lion's share" of the external funding for the project had come from the Government ($33.6million) and may compromise future attempts to bring further central government funding to the city.
That could mean other projects like the Velodrome or a Dublin St bridge replacement miss out.
She said if residents were picking up the "cost blow-out" it would severely test a community already struggling with the growing cost of living.
Deputy mayor Jenny Duncan said when councillors were told of the cost increase and the time delays of the redevelopment they were also presented with external funding options.
"We are hoping those can be exhausted before anything comes back on our ratepayers."
She said it would not be appropriate to say what those funding options were.
Fundraisers for the project had done an extraordinarily good job up to now, she said.
"I don't think many ratepayers realise just how little, or what a small proportion they are contributing to this."
She said once the project was complete, the city would reap rewards from it.
"Once the new gallery is open and the people of Whanganui are welcomed back into it, they are going to see what a magnificent asset and amenity [the city] has.
"And it's for everybody."
Councillor Kate Joblin said she expected an increase, but hoped it wasn't as much as it had turned out to be.
"I was aware that with delays due to getting the foundation work right on the existing Sarjeant building and movement in Covid levels that the project would have an extended timeline."
The new and completed Sarjeant Gallery would be of huge value to the community both economically and culturally, she said
But the Sarjeant's team needed to make sure the gallery was relevant to all locals.
She said if the council had to take on the full $9.4million - a "worst-case scenario" - it would need to spread it over 30 years.
"This will help ease the rate burden and ensure that today's ratepayers are not disproportionally encumbered by the cost of what is an intergenerational community asset."
Councillor James Barron said, while he wasn't on the council when the project was initially voted on, he thinks it makes sense as an investment for the city.
"The majority of funds is money that would not have come to Whanganui if not for the gallery," he said.
Councillor Graeme Young said anyone taking on a building project right now would be well aware of delays and increases in costs.
It was lucky the increase was only $9.4million, Young said.
"The final costs are anyone's bloody guess at the moment.
"Go down to the Mitre10 and try to buy the same thing for the price they were [12 months ago]."
Councillor Charlie Anderson said the cost blow-out was disappointing but inevitable.
"I am surprised it's not more," he said.
"We have some very capable fundraising people in our community, hopefully the council's input will be minimal."
Councillor Hadleigh Reid said the extra costs were disappointing to get after a thorough planning process.
"Unfortunately, this is an unpredictable time to build with significant cost escalations and disruptions over the past couple of years.
"We will do what we can to mitigate the pain."
Whanganui mayor Hamish McDouall said earthquake strengthening and restoring the 103-year-old building had presented a number of challenges for the construction team.
McDouall said the council would have to look at funding a portion of the shortfall, approximately $9.4 million, but it would do everything to bring funding into Whanganui from external sources.
