Opal Tower report finds multiple design and construction faults

An independent report has found multiple design and construction faults, including the use of inferior building materials and "under-designed" beams, led to damage at western Sydney's Opal Tower.

The newly-built 117m tower in Sydney Olympic Park was evacuated on Christmas Eve after bangs were heard and multiple cracks were found in the 34-floor building, sparking fears it could collapse.

The report, commissioned by the NSW Government and written by three senior engineers, identified multiple construction issues but did not lay blame on developer Ecove, builder Icon or engineering firm WSP.

While the building is structurally sound overall, horizontal "hob beams" used in its construction were of inferior strength and not compliant, the report found.

Sections where the beams were only partially covered with grout added to their instability.

"Our final report confirms that a number of structural design and construction issues, including non-compliance with national codes and standards were responsible for the observed damage at Opal Tower," the report's authors said.

"We found some of the as-constructed hob beams and panel assemblies were under-designed according to the National Construction Code and Australian Standards, leaving the beams prone to failure.

"We also found construction and material deficiencies likely contributed to the damage to the hob beams on levels 4 and 10.

"We consider that the building is overall structurally sound and the localised damage to the building can be rectified to ensure the building is compliant with the National Construction Code."

About 170 of the 392 apartments have been deemed fit for reoccupation, but hundreds remain empty, with families left stranded in temporary accommodation.

Icon has revealed that it is spending $1 million per week to keep stranded families in alternate accommodation.

Many residents have vowed never to return to the building, which was completed last year.

The experts recommended creating databases of registered engineers and building certifications, along with a building structure review board to monitor property design flaws and shape future building codes.

NSW Minister for Better Regulation Matt Kean said the government supported the direction of the report's recommendations.