Some residents are still in temporary accommodation nearly two weeks after cracks were found in the Sydney Olympic Park building on Christmas Eve.

After a preliminary independent investigation confirmed a number of design and construction issues, residents returned on Saturday to find their homes "absolutely trashed".

Pictures seen by AAP reveal one unit has had its ceiling and flooring torn away to allow equipment to prop up the concrete slabs separating each floor.

Beds, furniture and clothing were crudely piled near a window.

One woman told other residents in a social media group chat that her locks were changed, even though she provided a spare key to those working on her unit.

"It's absolutely trashed," she said in the chat.

"We are so upset

"This is horrific."

Close to fifty units have been gutted and dozens more are also set to be torn apart, Seven News reported.

"We're all very angry about this," one resident told AAP.

"I mean, at least send us a notice or something. It's just wrong for them to do things like this."

Opal Tower builder Icon said it has kept the body corporate abreast of their workers' movements through the building, as requested.

It said "a strict photographing" of apartments took place prior to investigation works and a second set of photos were taken when protection was laid out or furniture removed.

Referring to residents' fridges being cleared out, an Icon spokeswoman said power had to be isolated to enable works so perishables were removed in the interests of residents.

She said residents would be able to claim back immediately the cost of losses.

"Only one resident has stated we cannot enter his apartment and we have complied," the spokeswoman said.

"No locks have been removed, however some were damaged by emergency services."

Engineering experts Mark Hoffman and John Carter, who have been commissioned by the state government to conduct the independent investigation, said on Friday they'd found no evidence of issues with the foundations of the building.

They said they needed further information before being able to comment on or address any proposed rectification plans.

A final report is expected by Friday.

Australian Associated Press