The owners corporation behind the Opal Tower says it has "many questions" to be answered before it approves a plan by the builder for repairs on the damaged building — meaning residents could be homeless for months.

Key points: Icon, the builder of the Opal Tower, says repair work will take another four to six weeks

Icon, the builder of the Opal Tower, says repair work will take another four to six weeks The building's owners corporation says it needs to approve the repair work before it commences

The building's owners corporation says it needs to approve the repair work before it commences It means residents who have been homeless since Christmas Eve may be waiting up to two months to return their homes, or longer.

Icon, the builder of the 36-storey apartment complex evacuated on Christmas Eve after residents heard a loud cracking noise, told the ABC it expected remediation works on the tower to take another "four to six weeks".

However the Opal Tower owners corporation — which has employed an independent engineer to asses the building — needs to give Icon the green light before any repairs can occur.

The owners corporation, headed by resident Shady Eskander, said it was committed to ensuring all decisions were made with "a proper process", and called for a detailed management plan to be developed.

It means residents face a continued wait before they can return to their homes, which could potentially stretch well beyond the two-month mark.

The move came after the NSW State Government yesterday released its final report into the building, following a near two-month investigation.

The report found problems caused by changes made after the original Opal Tower design were exacerbated by "construction issues", with "lower-strength concrete" and "under-designed" critical support beams bursting under extreme pressure.

Icon confirmed 259 units in the 392-unit apartment complex at Sydney's Olympic Park are today still empty, with hundreds of families still in temporary accommodation.

Many have vowed never to return.

In a statement, Icon told the ABC it "welcomed the Government's findings" and believed the construction-related issues identified in the report had been "satisfactorily addressed".

Cracks stretch across a floor on level 10. ( Supplied )

"Icon is performing remediation work in seven areas of the building: two areas on level 4, two areas on level 10 and three areas on level 16," the company said.

"Remediation plans have been finalised and issued to the body corporate (owners corporation) for consent which Icon hopes will be provided without delay, as recommended by the report."

"Once consent is given, Icon anticipates the works will take approximately four to six weeks to complete.

"Icon is ready to undertake these works immediately."

The Opal Tower owners corporation said it had been actively seeking more information from all parties since the date of the incident.

"[We] have only received initial remediation plans eight weeks after the incident on Christmas Eve," it said in a statement.

"All residents are eager to return home but [we have] many questions that have arisen and need to be addressed with Icon in order for approval to be provided."

"As the NSW Government has also just released their findings, the owners corporation must digest all information provided, and would only issue approval to commence remediation after taking into consideration the independent opinions of all experts involved."

Some apartments in the building cost as much as $2.5 million. ( Supplied )

In the meantime, experts have warned of an "Opal Tower" effect causing a "feeding frenzy of negativity" in the off-the-plan apartment market.

Some residents have openly questioned whether they will ever be able to sell their apartments, some of which were originally valued at $2.5 million.

Ecove, the developer behind the project, said it welcomed the report on the building's faults. It described the process as "devastating".

"It is extremely concerning to have it confirmed again in this final report that changes made after the original design and exacerbated by construction issues appears to lie at the core of the problem," Ecove said in a statement.

"Ecove supports any initiative to ensure the integrity of the design and construction process, and return confidence to the community and to the building and construction industry."