"We tried to express our concerns on many occasions, and we just weren't being listened to," Lay said.
"Ten years after the earthquake, and the concerns that we raised back then, it turned into a reality and have resulted in what I estimate has been $10m worth of taxpayer money wasted.
"Where's the accountability?"
Despite the budget spiraling by 50 percent, from $27 million to $40m, the main 35-classroom block at the decile 10 state school, while made safe, is unfinished.
The ministry botched the job, and when Lay tried to hold it accountable, he says they went after him.
"In front of staff, they called me a health and safety risk.
"Just because I was holding them to account, they really, really did double down."
A senior ministry manager told Lay one of their employees had lodged a formal complaint against him, when they hadn't.
"That's the wider issue," he said.
"If any school speaks out, they certainly make it very difficult. They have the power in behind them, and they pick you off as individual schools.
"That's where schools need to be working more collectively."
All of Lay's issues had been investigated, including by the Ombudsman and Office of the Auditor-General, the ministry said.
It declined an interview, instead in a brief statement it focused on the school getting a new arts centre, and a repaired gym, with $25m spent so far.
"There is more to be done, and we are in regular contact with the school," said Kim Shannon, head of the Education Infrastructure Service.
The Girls' High principal, and the current board chair Julian Bowden, would not comment except to say they had positive expectations of a meeting due on November 4.
The ministry has completed 58 out of 115 schools under the 10-year Christchurch School Rebuild programme that began in 2013; it is behind schedule, though the ministry still says most schools will be ready by 2023.
"Some projects at larger secondary schools have already started but will continue beyond 2022/23 as they have been staged so the schools can remain fully operational," Shannon said.
A midpoint review in 2018 found the $1.13b budget was short by $150-300m, and it was boosted to $1.38b.
Cost blowouts and "woefully incorrect" ministry correspondence characterised Christchurch Girls' build, said Lay, a chartered accountant who runs his own firm in Leeston.
Documents including emails, letters, a ministerial memo and Ombudsman's finding, support his account.
They show the ministry failed to give the school's rebuild team key information:
• that the ministry aimed to strengthen the main block to 44 percent of earthquake code (or New Building Standard, NBS), not the 67 percent the school said it was promised.
• that consultants advised the ministry not to start work at the end of 2017 - it did anyway, and problems and costs ballooned.
• that it applied for and got $13m extra.
"They're pretty concerned they've wasted taxpayer money," Lay said.
Project manager RDT had told the ministry in March 2015 that bowling the main block and replacing it, would cost millions less than strengthening it, plus it could be rebuilt on more stable land away from the river.
Geotechnical consultants believed the ground was so poor that if they chose the retain-and-repair option, then a "worst-case" scenario of a $34m bill would eventuate.
Yet days later the ministry told Lay: "It is still the ministry's perspective that the repair option on the main block is the most viable and cost-effective option."
The main block stayed put.
This meant the school's replacement performing arts centre had to be built next to it, on the less stable land too.
Lay believes this added $3m to that project, which was completed in 2017, when the aim had been 2015.
Bureaucrats were making property decisions they weren't qualified to make, Lay said.
"Right back in 2013 ... we said your budget will not cover what you are telling us you're going to do."
"They started to realise it" and sought "shortcuts" with the 44 percent NBS aim, he said.
Minutes from a school meeting with the ministry in December 2015 say: "CGHS consider the basis for original budget was flawed."
The ministry acknowledged a three-month timeframe to fix the main block "was a risk" but it could manage it, the minutes said.
The school "did not consider they were made aware" of the 44 percent NBS decision, the minutes added.
"We found this out through contractors," said Mike Lay, "who alerted us to the fact that they'd been instructed to design to a lower standard.
"Therein started a battle between our school and the ministry to ensure that we were going to get a building that was up to 67 percent of code."
At heart, was a one-size-fits all school rebuild approach that didn't take enough account of what individual schools needed, Lay said.
An inflexible approach to school property funding was faulted in a 2017 Office of the Auditor-General report.
The school insisted on 67 percent, and won out but this blew out the costs.
It was disruption to students, though, that was the killer, Lay said.
The board expressed "extreme concerns" in early 2017 at the ministry's track record and statements about delays, at the "riskiest phase of the rebuild" for disruption.
Later that year, the ministry wanted to push on, even when experts told it not to start strengthening the main block, foreseeing big problems.
The ministry went ahead anyway.
"They ignored the consultants advice and continued to build," Lay said.
"They were never transparent with us around the fact that there had been advice from consultants not to proceed.
"They had an obligation to inform us of that, but they never did."
Documents show the ministry presumed the school would not want a delay that meant builders couldn't take advantage of the 2017-18 summer holidays.
Work began, but by April 2018 was entirely restricted to outside of school hours, to avoid disrupting classes, slowing things down.
Costs blew out. A premature halt was called. The main block, while safe, remains unfinished.
The ministry had sought and got $13.7m extra funding in April 2018, inflating the budget at just this school by 50 percent.
But it didn't tell the school this.
The Ombudsman, in May this year, described what happened when Mike Lay asked if it had applied for more money: "The ministry's initial responses were misleading, and appeared contradictory," the Ombudsman said, adding staff were not dishonest.
"It continued to dismiss his concerns. While the Ministry has now explained the situation, it has not apologised for the confusion caused by its statements."
Now it has.
Lay has received three apologies from the Secretary of Education, Iona Holsted, the latest in June this year.
She said they should have explained to him about consultants telling it not to start the build.
"I also apologise for the confusion that was caused by our statements regarding the funding application," Holsted wrote.
"In both of these situations we should have done a better job of explaining these situations to you from the start, and I am sorry for the way we managed the concerns you raised with us about this.
"I acknowledge that these failures on our part have caused you considerable concern and frustration over a number of years."
The ministry now considers these matters closed.
In the thick of the to-and-fro in 2018, the ministry told Mike Lay a staffer had laid a formal complaint against him; in this email it uses the words "intimidation", "harassment" and "bullying".
But it was not true - there was no formal complaint.
Secretary for Education Iona Holsted apologised but insisted her staff had genuine concerns about his behaviour
It had all taken a toll, Lay said, on him, on the board, on the principal at that time.
"To be fair, Iona Holsted has apologised ... she has recognised some of those issues, but it takes a toll.
"Hearing stories from other schools recently, and I'm thinking these are exactly the same issues that I've been through" and board, and principal.
"It's being repeated. So, yes, you get an apology, but what change has been made?
"I'm seeing behaviours and a toxic culture that exists within the ministry.
"Nobody's asking for heads to roll but they do have to be prepared to change their attitude."
Lay in June this year sought to raise the problems of school rebuilds with the education minister, but Chris Hipkins told him no, "the matters of concern to you are operational".
In the 2017 election campaign, Labour promised to form a new governance group to help the rebuild. It has not done that, but told RNZ that concerns had been addressed.
The ministry told Hipkins in December 2017 that Christchurch Girls' "entire" redevelopment under the Rebuild programme "is likely to be completed in 2018-19"; 12 works had been completed and there were four projects to go.
The ministry told RNZ that its Christchurch Schools Rebuild had so far spent $758m out of $1.3b.
It would deliver one of the "most modern schooling networks in the country, with 2,400 refurbished and new teaching spaces and more than 80 percent of these will be innovative learning environments".
The programme aims at:
• building 13 new schools on new sites
• rebuilding 10 schools
• redeveloping 92 schools over 10 years
"We're expecting to complete projects at 17 schools over the next 12 months," Kim Shannon said.
There were 31 projects in design and planning stages, 19 being built , and five out for tender.
