Two school classrooms were extensively contaminated with the most dangerous type of asbestos after the wall linings were taken off without any testing.
Emails released by the Ministry of Education under the Official Information Act showed someone at the unidentified school asking: "How could we have missed identifying the asbestos?"
The ministry said the case highlighted the complexities it faced in helping schools with asbestos issues.
Scores, if not hundreds of schools, have gone through or face disruption from asbestos.
The material, if broken, sanded or drilled, becomes dangerous by releasing tiny fibres into the air. These can lodge in the lungs and cause damage years down the line.
The ministry has spent a year looking at setting up a national list of approved operators to keep out cowboys.
It was still "investigating options" to help school boards, it told RNZ on Friday.
In the case of the unidentified school, an eight-classroom block was up for refurbishment in 2022-23.
It was initially declared free of asbestos.
But that declaration was wrong, and when the walls were opened up, two rooms became contaminated, along with heat pumps and radiators.
The asbestos was class A type, the friable type most prone to air dispersal.
"[Someone] notes that air conditioners and radiators are known to migrate asbestos," one of the emails said.
"We can either assume they are contaminated and remove and replace them with new OR test them. Testing will have its limitation."
The asbestos added at least $340,000 and months of delays to the refurbishment job.
Getting rid of all the asbestos took at least 10 weeks and required work during term time - outside school hours - and double shifts in the holidays.
The school's leaders emailed the ministry in late 2022 about the mounting "unwanted" pressure and stress.
"We have just had a meeting with the contractors for this project and it is potentially not looking good for us. I am reaching out again as I feel we need to get some action ASAP in order to avoid major problems for the school in 2023," one email said.
"We are currently waiting on another asbestos survey, however, is there a need to open up walls in live classrooms now when we can almost guarantee the design of the radiators is going to be the same as the classes where they originally found asbestos?"
"We are in full swing planning for 2023 and cannot move ahead any further ... I have to say that it is getting to the point where myself and our board are getting very nervous."
Eventually, the school got the asbestos-containing material removed.
But many others were not so lucky.
"There is a sizable number of locations where, after a removal, there is currently unsafe, residual asbestos which requires immediate intervention work," a mid-2023 internal ministry report said.
"Remediation has been performed by unqualified contractors in a manner which is often considered not legislatively compliant, in keeping with best practice, or safe."
The ministry acknowledged schools had been struggling with the issue.
That had persisted since at least 2016, when the government began increasingly and repeatedly stressing it was taking action to reduce deaths from asbestos generally, and to remove cowboy operators.
Yet the documents released under the Official Information Act and RNZ enquiries showed:
The Ministry of Education does not keep a 'black list' of bad removalists
It has not estimated the extent of asbestos-related risk across schools
It has not identified the number of schools that require an asbestos survey or an asbestos management plan
It has not set up national panels of consultants and removalists, despite discussing it for a year.
A small part of the mid-2023 report into setting up the panels referred to examples of defective jobs at schools. The ministry withheld that specific information from RNZ, which has asked for it again.
The ministry has used panels for other forms of quality control at school building projects - ones that, unlike asbestos, do not involve threat to life - since 2015.
Decentralisation under Tomorrow's Schools put the burden on boards of trustees, and when they ran asbestos projects, the ministry had little control, it said.
"Schools are not required to inform the ministry when asbestos removal has been completed poorly as part of school-led projects," property head Sam Fowler said.
The ministry "typically only identifies poor removals" when it took the lead.
Under law, schools with asbestos - identified or presumed, which was hundreds if not thousands of schools - had to have an asbestos management plan, Fowler said.
Whether they all actually did or not was unclear.
"The devolved model creates challenges for the ministry in oversight or performance management of asbestos removal activities it is not legally privy to," Fowler said.
The 2023 ministry report on setting up quality control panels said to gain a place, companies would have to adhere to stringent performance criteria and demonstrate that they got jobs done on time.
Adherence to health and safety protocols was another criteria.
The ministry did not tell RNZ when a panel might be set up, or if there would be one or two of them.
Weaknesses in the asbestos industry appeared to be a factor holding it up acting. "The current numerous service providers are in part contributory to the current poor state through the historical noncompliant remediation" of asbestos, the report said.
