Councillors at yesterday's full council meeting voted to close the museum from May 1 until its refurbishment was completed and a "grand reopening" staged next year.
That was expected to be by November 2012 - meaning an 18-month closure - although the exact date could be subject to change, councillors were told.
Most of the museum's permanent exhibitions had already been dismantled to allow work on the $35 million refurbishment, which began in 2008, to proceed.
A small part of the museum - comprising the former New Zealand Railways bus station booking hall and a nearby room - reopened late last year, offering two small exhibitions.
Museum director Linda Wigley said in a report to yesterday's meeting the closure of the remaining public displays would allow staff to focus on the redevelopment.
However, the museum's education, school holiday and other special programmes would continue, she said.
"We are not closing all of our operation.
We are just closing a couple of small exhibitions," she told councillors.
The decision to close the remaining exhibitions was based on "a high level of dissatisfaction" from visitors, her report said.
However, the exact timing of the reopening could be subject to change, depending on the outcome of the 2011-12 draft annual plan process, councillors heard yesterday.
Responding to councillors' questions, acting chief executive Athol Stephens said funding for the $8.6 million fourth stage of the redevelopment project - including construction of a new museum entrance - was included in the draft annual plan.
However, both the funding and the entire plan were proposals, and remained open to submissions, he said.
Submissions calling for a change to stage four of the redevelopment could require a staff report detailing the implications of any changes, he said.
Questions were also raised about the museum's staffing, which stood at 17 full-time equivalent staff but was expected to rise to "25 or 26" after the museum reopened, Ms Wigley said.
Cr Syd Brown asked staff to investigate the staffing levels needed during the museum's closure, and any savings that could be achieved either in staffing or operational budgets.
A report would be presented to the council's community development committee by June.
