Details of 50 Marcus Clarke Street's freak ceiling collapse revealed

The substantial ceiling collapse occurred when fixtures holding metres of air conditioning ducts in place gave way on the building's first floor in August last year, taking out the sprinkler system and crashing through the decorative ceiling below it.

A structural engineer has described the incident as "very rare", suggesting it's possible a manufacturing fault or a poor installation might be to blame.

The Canberra Times can reveal the building on 50 Marcus Clarke Street - home to staff from the Department of Education and Department of Employment and Workplace Relations - was closed until mid-November as a result of the incident while repairs were underway to fix the ceiling collapse and resulting water damage.

No-one was injured when the ceiling, which covered an area between the lift and staff work desks, collapsed.

Public servants were first told of the building's closure on Saturday evening on August 27 due to "minor flooding" in its north-east corner along Rudd Street.

Text messages and all-staff emails warned staff against coming into the building on Monday.

An investigation revealed the fixtures holding that section of the duct in place were "insufficient" to hold the weight of it, a department spokesperson said.

But those fittings had also been used throughout the building's air conditioning duct system, prompting concerns it could occur again if they weren't replaced.

During September and early November, engineers assessed air conditioning ductwork on other floors and determined additional areas had failed, or might fail, resulting in further work being undertaken.

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Staff were eventually let back into the building from November 10 after the engineer gave the green light, with some floors remaining closed while further repairs were done.

"The upmost priority of the department is the safety and wellbeing of its staff, which is why it worked closely with the building owner to progress investigations and rectification works so that the building could be safely reopened," a department spokesperson said.

Mal Wilson, head of Campbell-based firm Advanced Structural Designs, said questions now remained over how the rare incident happened, and what factors might have lead to it.

"When there is a collapse of the AC ducts - which is relatively rare - Work Cover and others will be interested in determining the cause," Mr Wilson said.

"The cause will often reveal whether the problem can be attributed to poor documentation, poor installer or a manufacturing fault of some sort.

"Establishing the cause will often reveal if the problem is isolated to the building or if the failure has wider ramifications for the industry."

The 50 Marcus Clarke Street address has before been marred by building fiascos.

During its construction in 2008, a slab of wet concrete collapsed after its support structure gave way. No-one was injured.

Despite such incidents, the office building sold for $335 million in 2021 to investors Charter Hall and GIC, a Singapore-based investment company.

The Education and Employment departments are expected to remain at the location until mid-2026 when both workforces will move to a new 11-storey building on London Circuit after securing a 15-year lease.

Do you know more? Contact Sarah confidentially at sarah.basfordcanales@canberratimes.com.au or sbasfordcanales@protonmail.com

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