Opal Tower has become an ‘Australian nightmare’ for residents

A report on what caused large cracks to appear in a Sydney skyscraper - forcing a mass evacuation - has revealed a probable cause.

Residents of Sydney’s cracked Opal Tower still have no timeline for when they can return to their apartments, despite an independent report declaring the building is structurally sound.

People continue to live in temporary accommodation, more than three weeks after the first cracks were noticed in the 36-storey building they had been calling home.

An interim report released on Tuesday ruled out dodgy materials and extreme weather causing the large cracks on Christmas Eve.

Anxious residents wait to hear news about their homes in the tower block foyer. .

But numerous construction and design problems were detailed, including reinforcing bars in some areas being the wrong size.

“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,” the report’s authors, Professors Mark Hoffman, John Carter and Stephen Foster, said.

Promotional image of Opal Tower (right)

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

They recommend independent and qualified structural engineers be contracted to check final proposals in detail before major rectification works begin.

Opal Tower body corporate chair Shady Eskander says hundreds of residents won’t consider moving back in until a comprehensive review of the building is completed.

“The worst thing that can happen is that in a couple of years down the track we have an incident occur again,” Mr Eskander told reporters.

“People were buying into the Australian dream and unfortunately this has become an Australian nightmare for us. We have suffered.”

Mr Eskander said that he expected the matter to go to the courts.

Shady Eskander speaks at a press conference in Sydney to release the interim report, with (from left to right) Professor John Carter, Professor Mark Hoffman, NSW Minister for Planning and Housing Anthony Roberts and NSW Planning and Environment Secretary Carolyn McNally. Picture: Joel Carrett/AAP