The contractors also didn't have the correct Auckland DHB permits, and hadn't completed a pre-qualification health and safety process, despite being asked to.
"The project was procured under a design and build contract due to workload pressures being experienced by our more familiar design consultants," the board was told at a February meeting.
"Immediately prior to the incident the construction team diverted from the original method described in their safety plan."
An Auckland DHB spokesperson told the Herald on Sunday the original plan was to use a saw cutter only, and not a hydraulic concrete breaker as well.
The project involved building a new cool room inside a kitchen on level 5, and demolishing a loading dock to make space for future development.
"Work was stopped immediately and the area secured by the project team. WorkSafe was notified in line with standard protocols and independent investigations are being carried out by the external construction company, Auckland DHB and the third party project management company. These investigations are ongoing and likely to take a few more weeks."
Demolition work has been paused until all reviews are done, the DHB spokesperson said, with some remediation work to make the area safe.
"We are grateful that no one was hurt in this incident and take health and safety and building compliance requirements very seriously. We will apply any learnings ... to ensure there is not a repeat of this incident."
A large amount of building work has been carried out at Auckland and other hospitals to prepare more room for Covid patients, including fitting more negative pressure rooms and separating wards and areas for patients with the virus.
Another health and safety incident brought to the board's attention was a staff member suffering moderate injuries after being attacked by a patient they visited in the community.
A review found the assertive community outreach service, which cares for people with psychotic and mood disorders, was under "capacity and schedule-related pressures", which increased the risk of violence.
"Key learnings" included "continuously review and update high-risk caseloads that will require two people to be in attendance at visits to patients in the community".
Other DHBs are grappling with violence against staff. Recent incidents at Northland DHB, for example, include a near-death from strangulation and brain injuries.
The DHB believes Covid-19 and resulting restrictions had played a role in some attacks, with some people in the community being "tired and less tolerant".
