Ipswich Borough Council (IBC) has voted to continue supporting the redevelopment of Ipswich Museum after a £2.7m overspend.
The museum closed in October 2022 for renovations and expansion, initially budgeted at £8.7m, half of which was funded by the National Lottery Heritage Fund (NLHF).
Now with an estimated cost of £11.4m, after rising inflation and supply chain issues, IBC voted on 6 February to ensure the project is delivered in full, unanimously deciding to apply for a second round of funding from the NLHF.
According to a council report, NLHF has indicated that it will consider an additional funding application if the council provides match funding.
At a committee meeting, the council was warned that, if rejected, the project could be subject to a complete review, halting it for at least 18 more months.
"It's really hard to see what other option we have because we are so far down this road now," said Conservative councillor Ian Fisher.
"If we don't vote for it, we get something that's not going to be anywhere near what we wanted."
Labour councillor Carole Jones, portfolio holder for planning and museums, said: "There are improvements that we need to make, and this is not an extravagant scheme.
"We are where we are, and we can only go forward."