“It’s no easy job to remove any object in the museum’s collection, particularly the large objects like the Catalina and Locomotive No.1, but even small objects,” former deputy director Jennifer Sanders said. “The greatest cost and risk is in any movement of any collection.”

While there have been minor works to ensure its continued operation, the Minns government maintains there have been no significant capital works since the museum opened 36 years ago.

It released a list of works prepared by engineers Arup and Steensen Varming including repairs to the roof of the heritage-listed Turbine Hall and Boiler House and 1988 additions – the Touring Hall and Galleria.

Arts Minister John Graham said the building had significant problems that must be addressed without delay, including leaks from the roof and large cracks in several walls. These leaks had resulted in mould and damp, and put the collection at risk.

“At times of heavy rain, items on display need to be covered in plastic to ensure they don’t get damaged by leaks,” he said.

“To put it bluntly, the current Ultimo building is not up to the standard of a world-class museum that NSW wants it to be,” he said. “A museum requires temperature control, and a dust and pest-free environment to ensure the safety of the objects on display and in collection.”

PSA general secretary Stewart Little said his members were “devastated” by Sunday’s closure and suggested cost-cutting was driving the decision to close the museum weeks before public consultation had begun.

“We know there are problems with the roof,” he said. “OK, we’ve got a leaky roof but three years to fix it? Who are they going to get to fix it? A one-armed bricklayer?”

A project spokesperson said the drivers for the building’s revitalisation were multiple and included the escalating cost of reactive maintenance to preserve the building fabric and ensure the safety of visitors and the Powerhouse Collection.

Such costs were escalating due to the deteriorating state of existing building fabric and systems.

Loading

Upgrades were required to enable the existing infrastructure to support a quality visitor experience.

The revitalisation would also address the changed urban setting of the museum since the building opened in 1988. Existing building fabric and systems have reached a point where they need major interventions.

Overall, the current condition of the building fabric, Infrastructure NSW said, posed a significant risk to the Powerhouse collection and the operation of the museum through the ingress of water, dust, and other environmental contaminants.

Find out the next TV, streaming series and movies to add to your must-sees. Get The Watchlist delivered every Thursday.