The government is launching an inquiry after RNZ revealed more than 100 new classroom builds were in doubt.
Education Minister Erica Stanford, speaking alongside Prime Minister Christopher Luxon at the weekly post-Cabinet media briefing, said the government had inherited a school property system "bordering on crisis".
"Within weeks of forming a government, the Ministry of Education had already paused 20 building projects and informed me that there could be up to 350 projects in various stages, from design through to pre-construction, where expectations far exceeded what could delivered," she said.
"There have been a number of cost escalations and some schools expecting exciting, bespoke building projects that are not able to be delivered on."
She announced an inquiry would be set up - with a lead reviewer and review team to be appointed immediately - tasked with reporting back in three months.
"There is a clear need to review the school property system to evaluate the sustainability and efficiency of current arrangements and ensure we can deliver the school property our children deserve, while protecting taxpayers from further inefficiencies and poor value for money," she said.
Stanford said some of the projects were weeks away from shovels in the ground, but "funding available hadn't been managed well enough to meet what schools understood had been approved".
One example was the Te Tātoru o Wairau Marlborough schools co-location project, she said, "which had years of cost escalations with construction estimates of up to $405 million, despite originally only having $170 million allocated by Cabinet in 2018".
It follows reports by RNZ which revealed major projects at 20 primary schools and colleges - some of the roughly 300 new classrooms promised in last year's Budget - had been put on hold.