Around 650 people who were working on the $336 million repairs of Auckland's $750m NZ International Convention Centre are offsite under alert level 4.
John Salier, project director for the CBD job for Fletcher Construction, said the lockdown barred all but essential building work.
Fixing the NZICC after the fire two years ago is not deemed essential.
Fletcher's first move had been to ensure the site was safe, he said.
"As soon as yesterday's news came through, we safely secured the NZICC and Horizon Hotel sites and they will remain closed under Covid-19 alert level 4.
"Our first concern is always for our people, so we will be in touch with staff and subcontractors to make sure everyone is safe and has the support they need," he said.
One staff member was on site this morning to talk to anyone who missed yesterday's announcement, "especially as many contractors have English as a second language," Salier said.
Around 650 people had been on the site each day, he said, but now only a skeleton crew remained.
"We do have a roster of staff for site security and safety. This includes security on the perimeter, as well as monitoring and maintaining our temporary services.
"Work has continued on site over the past few weeks including the deconstruction of the upper roof frame, removal of the fire-protection paint from all the primary structural steel and removing the level five façade for damage assessment," Salier said.
Planning work would continue during the highest alert level, preparing for work resumed "for the weeks and months to come", Salier added.
Ross Taylor, Fletcher Building chief executive, yesterday delivered a stand-out company result.
The company exceeded even its own upgraded profit guidance, posting its full-year result just as all non-essential construction sites throughout New Zealand went into lockdown.
The business declared earnings before interest, tax and significant items of $669 million for the year to June 30, exceeding the top end of its own guidance range of $665m.
Last year's $7.3b revenue rose to $8.1b and net profit after tax turned around from last year's $196m loss to a stellar $305m profit.
Asked how the NZICC work was progressing, Taylor said "really strong progress" was being made.
"You don't have to wear heavy-duty PPE due to the mould. They're removing steel work. That's all got to come off. All the facade has to come off and re replaced. There's a fair bit of work getting the upper levels ready and the basements cleaned after handing back all the cars," Taylor said.
The Herald reported last month on work removing windows and glass panels which are works of art.
Reinstatement work would see more than 300 window panels and 100 glass art fins removed from the building's façade, Salier said last month.
Around 80 per cent of that work has been completed by late July.
That allows protective intumescent coating on the building's structural steel columns to be stripped and reapplied, following damage caused by the October 2019 fire, he said.
Intumescent coating is a passive fire retardant and protector for the steel.
Taking out the windows and glass art was an important step in redelivering the project after the fire nearly two years ago, Salier said.
Removal also allowed a detailed assessment of fire damage at the centre.
Fletcher's annual report also recalled the fire which broke out on October 22, 2019 and explained its role in terms of being an insured party because it's the head contractor, with significant equipment on the site.
The report also cited damage to the Horizon Hotel between TVNZ and the NZICC.
"Contract works and third-party liability insurances are in place on the project and the Fletcher Construction Company is an insured party under these policies.
"The group has assessed all relevant known facts and circumstances related to the estimation of cost to complete and insurance recoveries and concluded based on current information that there is no additional requirement for provisions in these financial statements," the annual report said.
"The group's assessment of the cost to complete relies on application of estimates and judgements, for example measurement of remediation's cost to complete, the likelihood of receipt of insurance recoveries and quantification of any claims and costs that are outside of insurance cover, and as such may be subject to change as the project progresses," that report said.