Ann Barsby, of the Gasworks Trust, said a preliminary application already had been made to the city council, through its annual plan process, seeking about $2 million over the next five years.
More than $1 million was needed to protect the main engine house building- the roof of which had been prone to leaking - and associated buildings.
If further leaking occurred ''that's when things deteriorate very quickly,'' she said.
That building, housing much of the working gasworks equipment, did not fully comply with modern earthquake standards.
It was believed that brick repointing and other work, perhaps amounting to as much as $100,000 worth, would also needed to be done to protect a tall and distinctive brick chimney on the site (pictured above).
On top of that, a storage building was needed, to protect some of the museum's heritage treasures.
The city council's property department had recently commissioned a structural engineering report, being undertaken by Lou Robinson, and a conservation plan for the future was being prepared by archaeologist and museum board member Peter Petchey, she said.
Also, a fuller submission from the board would be made soon, Mrs Barsby said.
Some ''very encouraging'' progress had recently been made with the museum, and a key turning point had come when the $900,000 restoration of the museum's fitting shop had been completed in 2011, with strong backing from the city council.
The council was providing strong overall support, but it was crucial to maintain the momentum in safeguarding the other buildings and structures at the museum site, with work undertaken in phases, over several years.
All buildings at the Braemar St museum site are owned by the council and are ranked as nationally significant, enjoying category 1 status, the highest level of Historic Places Trust heritage protection.
The museum, regarded by international heritage advocate Sir Neil Cossons as the finest working gasworks museum of its kind in the world, was showcased at a big national industrial heritage conference last year.
