'Absolutely no danger': Developer defends evacuated Opal Tower building

About 300 residents were told to leave Opal Tower at Sydney Olympic Park on Monday afternoon after fine cracks and a split in the wall on level 10 sparked initial fears the building could collapse.

Most residents were allowed to re-enter later that evening, although 51 apartments in the 36-storey tower were deemed unsafe.

Some residents were still unable to get back into their apartments on Boxing Day.

Ecove director Bassam Aflak on Wednesday defended the "high-quality building". He said the company was "stunned" by the damage and the project's builder, Icon, was a "well-established high-quality builder".

"Icon ... has full liability on the design and construction of Opal Tower.

"They are the experts, and Ecove has outsourced that expertise ... Ecove has delivered a project that is well above the industry standard.

"Ecove remains a significant owner of properties within the building. We, like the residents, are anxious that the builder defines the problem and resolves it as soon as possible."

A spokeswoman for Icon said the company has "dozens" of experts investigating and is hopeful the engineering report will be completed soon.

"As the builder, Icon accepts its responsibility for what’s taken place, and is working around the clock to ensure the matter is fully investigated," the spokeswoman said.

"There will be compensation for out of pocket expenses for everyone who was displaced on Christmas Eve."

Mr Aflak said a concrete panel was believed to have caused the damage. "The important fact is that there is absolutely no danger for the residents. We’re confident this localised issue can be fixed. Most people are now back in their homes."

"Importantly, the authorities have deemed it safe for people to re-enter and they have isolated the issue to a small number of apartments."

The NSW Planning Department approved the 36-storey tower as a state significant development, bypassing local council approval, in 2015.

The structural engineers were WSP, and the construction and occupation certificates were issued by private building certifier McKenzie Group Consulting, an Ecove spokesman said.

Planning Minister Anthony Roberts said the findings of his department's urgent probe into the steps taken to ensure the building's "structural integrity" would be made public.

A Planning Department spokesman said the state significant development process followed the same "rigorous and thorough assessment steps" as a local council approval process.

Opposition Leader Michael Daley said there was "nothing wrong with private certification" as long as it was "done properly and not in a hurry, by an appropriately qualified person".

However, he said reforms to ensure developers could not choose their own private certifier would improve the certification process.

"I think we should have a 'cab rank' rule where you take the certifier who's allotted to you."

Mr Aflak said residents were covered under warranty. In NSW, the statutory warranty period for "major defects" to buildings is six years.

Sydney consultant Ross Taylor, who specialises in building facade and waterproofing defects, said the building damage pointed to "a broader pattern in the industry".

He said the city's development boom in part meant that designers faced increased pressure from builders and developers to produce buildings that were cheaper and quicker to construct.

"Major defects are usually related to design rather than construction error," he said.

On Wednesday there was widespread anger amongst apartment owners at Opal Tower, some of whom are also residents in the building.

All of the apartment owners the Herald spoke to requested anonymity.

“I’m furious about what’s happened,” one owner said. "This is the most hideous Christmas."

“Maybe someone should be put into prison for major negligence.”

The apartment owner described the cracking as “unprecedented”.

“We want to know who is responsible. We pay tax, we pay stamp duty. The government should do something to protect us.”

Sain Sosor is a tenant in one of the apartments. She said she plans to move out as soon as her lease expires in February.

"Lucky I did a six-month lease," she said.