Fire and Emergency New Zealand has finished its investigation into the SkyCity blaze and is handing back control of the ruins to Fletcher Construction.
FENZ has had control of the building since the fire broke out at SkyCity's new convention centre on October 22.
Although no details are yet available of the findings, area manager Richard Twomey said investigators are preparing their report and it will be released in "due course".
The fire was complex and dangerous, with about 130 firefighters attending at its peak, along with 30 appliances and 16 operational vehicles, Twomey said.
"I have been very impressed with the professionalism of our firefighters, who worked long hours in trying conditions.
"This was a testament to the outstanding women and men we have working at Fire and Emergency."
Fire crews came from across Auckland and as far south as Hamilton to battle the flames.
Twomey thanked Fletcher Construction for the use of cranes and operational support during the past 11 days, as well as Auckland Council, St John and police.
He also thanked the wider community "for their support while we worked to get this large and complex fire under control".
A Fletcher Construction spokeswoman said access to the site is restricted while safety and structural assessments are completed.
"It will take us some time to understand the extent of the damage to each area within the seven-level, 32,000sq m site.
"We need to assess every floor, every structure and the 1327 car parks beneath the fire where there is significant water damage."
The company is prioritising getting vehicles out of the building, because many of the workers have been without their cars for a week.
They will also look to retrieve personal belongings and tools where possible, she said.
But it will be "some time" before workers are allowed back into the building to begin a clean-up.
"This has been a very challenging period for our client SkyCity, for Aucklanders generally and for our people," she said.
"They are devastated about what has happened and face a huge job ahead of them now."
Traffic restrictions will remain in the city centre over the weekend as Fletcher undertakes safety assessments.
CEO of SkyCity Entertainment Group Graeme Stephens said the focus for the team now is working with Fletcher to assess the damage and working towards how it can rebuild.
"From the outset, we have shared our vision for the NZICC, New Zealand's meeting place for the world, and we will work hard to ensure that it not only opens but provides world-class conference, exhibition and entertainment spaces for Auckland and New Zealand."
Both companies thanked the FENZ teams for their ongoing efforts.
E tū union is throwing its support behind the teenager at the centre of investigations into the SkyCity fire.
Nothing is yet proven about the cause of the fire, and E tū union, like everyone else, is waiting for the findings of the inquiry, E tū special negotiator Joe Gallagher said.
"Anyone can make a mistake and people in construction work in hazardous environments. The fire is a reminder of that," he said.
"But it's been good to see the main conversation about the young guy so far has been one of concern."
The union is providing support to the apprentice at the centre of the investigations, as well as construction workers, he said.
A source told the Herald the teenager, believed to be 18, was working for a sub-contractor and after realising his mistake went back to his work spot only to discover a fire had already started.
"The poor guy is in tatters ... he's completely shattered," the source said.
FENZ has released some information of its response by the numbers, showing 130 firefighters and 30 appliances responded to the blaze at its peak.
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Earlier this week psychologist Sara Chatwin told the Herald the realisation that you've caused a huge blaze would be "pretty horrific".
"He will be in shock and disbelief that he actually did that because as much as he left the blowtorch on or whatever he did, he will have been trained that obviously you don't do that - so obviously it's a big oversight that he will feel terrible about."
Gallagher urged construction workers to check if their workmates are okay, as the sector launches a programme targeted at reducing the industry's high suicide rate, the highest of any industry in the country.
The programme, Mates in Construction, is crucial to improving the mental health of workers in the sector, he said.
"This industry is booming, and it should be healthy, with satisfied workers earning decent money. Instead, it's precarious, fragmented and uncertain."
This then affects the wellbeing of workers, he said.
"We all need to be more supportive of each other."