Significant rectification works will be needed in the beleaguered Opal Tower in Sydney’s Olympic Park.to repair and strengthen damaged hob beams and in some cases the panels that rest on them, according to a preliminary report by building engineering experts.

The probable cause is in localised structural design and construction issues, say Professors Mark Hoffman, John Carter and Stephen Foster, who recommend independent oversight and review by qualified structural engineers before any major works begin.

They declined to advise when it would be appropriate for residents to return saying that was “was a matter for residents and the builder,” under the guidance of building engineers.

Minister for Planning and Housing, Anthony Roberts, in presenting the preliminary document stressed, that it was an interim report and the full report with the team’s recommendations would be made public and acted upon when completed.

“Our interim report confirms a number of factors may have contributed to the damage, although we have ruled out extreme weather, poor quality materials and issues with the foundations,’ the report by Professors  Professors Hoffman, Carter and Foster begins.

“We can confirm that, while the building is structurally sound, significant rectification works are required to repair and strengthen damaged hob beams and in some cases the panels that rest on them.

“However, while we have isolated the probable cause to localised structural design and construction issues, we need more information to make definitive conclusions about the cause or causes of the damage to this structure and the proposed rectification.

“We agree that the structural principles behind the rectification works are sound, but recommend independent oversight and review by qualified structural engineers before any major works begin.

“We also believe more work needs to be done to check the structural design of the hob beams and associated structural members with consideration given to strengthening them wherever they are in the building.

“We recommend that independent and qualified structural engineers be engaged to check final proposals in detail, before major rectification works begin.

“The focus of our investigations to date, and thus this interim report, has been on determining the basis of the failure and the steps needed to ensure the safety of the building for residents.

“Re-occupation of Opal Tower extends beyond the scope of this investigation and was a matter for residents and the builder, subject to appropriate engineering and design oversight and guarantees.

“More work is also needed before we can provide recommendations on what needs to happen to avoid incidents like this in future.”

Mr Roberts said that from the beginning, the Government’s paramount concern has been for the safety and welfare of all the residents.

He said the team had made multiple visits to Opal Tower site to inspect the damage, conducted reviews of the design of relevant sections of the building, construction records and quality control records, and met with the building’s structural designer WSP and builder ICON.

“I have been impressed with the efforts of all parties to work together to get to the heart of the issues and to help owners and residents get access to their properties as quickly as possible.

“I trust that this independent interim report will be an important input to the discussions between the builders, the owners’ corporation and residents about moving people back into the building,” he said.

A full copy of the interim report is available at: https://www.planning.nsw.gov.au/interimopalreport