Australia’s Race to Uncover Crumbling Concrete Threat!

Wood Central understands exposure is lessened with the autoclaved aerated concrete approved for cladding and non-load bearing wall systems only.

Sat 09 Sep 23


Governments across Australia are urgently checking public buildings to see if they contain aerated concrete, deemed dangerous after the UK Government ordered schools to be closed amid crumbing concerns.

Wood Central understands that the highest exposed jurisdictions to the crumbling material are Queensland, New South Wales and Victoria – which could lead to crumbing cladding and prefabricated wall systems being replaced by timber or steel-based alternatives.

On Thursday, Wood Central reported that more than 100 schools across the UK were scrambling to make arrangements after facilities containing the material were to be at high risk of collapse.

In response, the UK Government is now working to rapidly replace the crumbling material with timber joints – with experts now pushing for increased monitoring to cover tens of thousands of additional buildings which used the material.

The crisis has dominated headlines, with thousands of students already sent home and no indication of when they can return. 

The cost of fixing schools has already surpassed £150m (A$300m), with the UK Government under pressure over their inaction after experts warned of the looming crisis.

The global use of crumbling material

The bubbling material – a cheaper alternative to standard concrete with a lifespan of 30 years – has been used extensively in Australian construction projects. 

Primarily used in architectural layouts in schools, hospitals and other buildings, its panels can span up to six metres without an intermediate support column, are lighter than standard concrete and can be easy to build and dismantle.

Globally, the product has been used widely for decades – it is popular in Turkey and Japan, mainly due to its excellent earthquake performance and is still in production in Germany and the US.

Limited to walls and prefabricated building materials in Australia

However, crucially, in Australia, at least, it has been limited to walls and prefabricated parts of the buildings and not roofs, floors or structural elements like in the UK.

The product use is subject to the standards defined in the Australian Building Codes Board (or the ABCB), with regulation and compliance overseen by states and territories.

The product, known as autoclaved aerated concrete (ACC) in Australia, is therefore only permitted in wall and cladding systems in Australian homes.

Speaking to the Guardian Australia, Gary Rake, the CEO of the ABCB, said this vital distinction makes it “a lower-risk profile” than in the UK.

Nonetheless, he acknowledged that the product could be used in other buildings when “there’s more likely to be a complex and highly skilled design team involved – perhaps architects, engineers and builders working together”.

The Australian standard then set out “a range of different parameters around design, appropriate use … and the assessments that need to be made”, he said.

Mr Rake has “no new concerns” but was examining the information from the UK and would adjust the frameworks as required.

According to Gary Rake, the CEO of the ABCB, Australia’s exposure to crumbling concrete is much lower than other countries, given its limited application to cladding and wall systems. (Photo Credit: Supplied from the Fifth Estate)
UK experts raise concerns over long-term deterioration when wet 

In the UK, a team of experts led by Professor Chris Goodier claimed that the threat caused by concrete composite was much higher than first thought.

It claims that little research has been conducted into the product as it ages and identified three main factors that were not fully taken into account by risk assessors:

  • The product soaks up water like a sponge and increases the load on the building if it is exposed to rainwater.
  • Stress tests showed it becomes 25% weaker when wet.
  • An analysis under a microscope showed that cracks can appear around the steel rods running through the material.

According to Misha Ketchell, editor of the Conversation, “Evidence shows that the behaviour of these panels can no longer be predicted reliably due to uncertainties in the material and the mechanical properties of the panels, which are highly impacted by deterioration.

“This is simply because the panels have been used far beyond their intended design life and, in many cases, without proper maintenance,” he said.

Queensland is investigating AAC’s use in wall-based installations

The Queensland government told the Guardian Australia that it is unknown how much of the product was used in wall installations across the state.

However, it reports that an assessment of its use in all government buildings is now underway.

It confirmed that it will take action if material use falls short of Queensland’s high safety standards – “regarded as the strongest in the nation.”

“We are working closely with the ABCB to understand the extent of their use nationally fully,” the Queensland Department of Energy and Public Works said.

“We are also working with other state government agencies to determine whether AAC products have been used in Queensland government buildings.” 

In New South Wales, exposure is limited to pre-2017 school projects

Meanwhile, in NSW, the State Education Department confirmed that following the development of the School Infrastructure NSW in 2017, the state now requires that “structural materials with long life spans” be used in all school projects. 

This effectively cuts AAC out of government procurement, given its 30-year life span.

A spokesperson confirmed that reinforced autoclaved aerated concrete “is not suitable for use as a structural material as it does not meet the requirement of having a long life span.”

Before 2017, NSW Public Works managed all school construction projects, with materials specified in accordance with department requirements.

A NSW Fair Trading spokesperson said buildings are regularly audited, with all noncompliances managed through rectification orders.

Nonetheless, a government source said the State’s Building Commissioner was unaware of any risk caused by the material use and the AAC in NSW.

All other states have deferred to the ABCB for further action

In Victoria, a government spokesperson said it was working with other states and the federal building board to assess the risk.

“We are aware of the emerging issue in the UK and are working with other states and territories and the ABCB to determine if there are any risks to Australia.

In the ACT, Northern Territory and Tasmania, the relevant government authorities are also working with the ABCB “to understand the risk to government buildings which use autoclaved aerated concrete.”

Whilst in South Australia and Western Australia, government spokespeople from both jurisdictions confirmed that there was “no record of any instances of these planks being used in our (SA) existing buildings” and “little to no use of autoclaved aerated concrete as structural elements in any WA building.”

We need to live with AAC like we live with asbestos

Meanwhile, expert researchers in the UK are now using the term “living with RAAC” and say the material must be dealt with, like the asbestos crisis of the 1980s and 1990s.

According to Professor Chris Goodier, most impacted buildings in the UK were not dangerous but should be inspected “just in case.”

“We’ve suddenly discovered that a certain proportion of our building stock is not as good as we thought it was,” Professor Goodier said.

“It’s a small proportion, but we have millions of buildings – even if it’s just one per cent of 10 million, that’s 100,000.”

As well as government buildings, including hospitals, courts and prisons, an unknown number of private sector offices and warehouses were also potentially exposed because they contained the materials.

‘But the public sector is the easy bit because the government has control over that and knows where it is,” Professor Goodier said. 

“But when you move to the private sector – you are mainly looking at the 1960s, 1970s offices, factories and warehouses and possibly some housing where you may not know who owns it.”

It is not understood how many buildings in Australia have used AAC in cladding and wall systems.


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