Among "major capital maintenance projects", overall spending on the two roof projects was estimated to range from about $900,000 to $1,738,000, a report tabled at a recent Otago Museum Trust Board meeting said.
The lower estimate comprised $500,000 for the old building roof, and $400,000 for the Tropical Forest, but full slate replacement of the old roof was estimated at $1million and $738,000 was a higher estimate for the forest roof.
These roofing options were part of overall capital maintenance requirements ranging from $2,100,000 to $3,248,000, including estimated costs to extend the museum's sprinkler system into older parts of the museum complex, ranging from $1.2million to $1.51million.
Museum director Ian Griffin said the museum was not funded to meet such capital maintenance costs.
This was partly why the museum was seeking more funds from contributing councils and would also undertake further fundraising.
At the board meeting, answers about roofing options for the 1877 building were sought, given its heritage protection.
Museum commercial director Murray Bayly said the current roof was not slate, and very little of the roof could be seen from outside the museum.
Apart from the high costs, there were other significant issues with using slate, including that people could not walk on it, which posed health and safety challenges to do any later work.
The museum had already had some constructive discussion with Heritage New Zealand, and the roofing issues for that building were a "work in progress".
Mr Bayly said the Tropical Forest roof had to allow sunlight in while keeping rain out.
