The earthquake-prone Carillon bell tower in Wellington may take more time to fix than deadlines allow.
The landmark heritage building and its 70 tonnes of bells have been closed for more than a year, after belated engineering reports exposed weaknesses not addressed by stop-gap seismic upgrades since 2012.
The Manatū Taonga Ministry for Culture and Heritage has till only next May to strengthen the tower under tightened earthquake safety laws.
"However, we are considering applying to Wellington City Council for an extension," deputy chief executive of delivery, Tamsin Evans, said in a statement.
"Our aim has always been to make sure we do the work well rather than doing only what can be done by the deadline."
The project at the National War Memorial has a budget of $7.2m. "This is an estimate only and will be refined as we progress", Evans said.
Engineering reviews last year exposed fundamental problems, such as how the 50m-tall tower's foundations wouldperform in a quake.
Though the ministry earlier had a "detailed seismic assessment" done, a review found that this DSA had left about half of 40 basic questions about the tower unresolved.
Evans said the ministry was now engaging the help it needed
"The first stage of the project will confirm the design solution and cost before the next stage of carrying out the strengthening and construction work."
The council approached the ministry about this in February this year, Evan said.
It was asked to start getting documents together if it aimed to extend the deadline, and it would meet the council this month to discuss this, she said.
It remained unclear how much longer might be needed.
"We have not yet contracted a project management supplier who can advise us on further testing that may be required and timelines for solutions.
"Only when we have selected a preferred option for the strengthening will we be in a position to set a deadline for completion of the works," Evans said.
Anzac Day parades have had to take place without the carillonist ringing the bells, and the tower's parlous state has kept the Hall of Memories adjoining it shut too.