A population expert is warning that the record growth stretching Auckland schools could get even worse.
Massey University professor Paul Spoonley told RNZ official forecasts of 50,000 more school-age children in the region by 2030 were conservative and the government was not building new classrooms fast enough.
He said this year's growth of 4113 extra students at 1 July - the region's highest in 16 years - should ease for the next two years due to the impact of border controls before picking up again.
Professor Spoonley said this year's growth was probably driven by record inward migration in the 12 months to the middle of the year.
"Immigration is a major contributor to that growth and so we're not going to see immigration return to its pre-2020 level for I suspect two or three years, so that contributor to growth will drop out," he said.
"However what we're seeing in Auckland is intensification of suburbs, so you're seeing more people in those suburbs and you're seeing more people of child-bearing age.
"So the past immigration growth of Auckland means that we're seeing immigrants now contributing to fertility, so it's keeping those fertility levels up and therefore that school-age population up as well. And of course the other thing is we're also seeing the children of immigrants now reaching child-bearing age."
The Education Ministry had forecast Auckland schools would grow by 60,000 children from 2017 to 2030 and the first three years of that period had seen growth of about 10-thousand children, meaning a further 50,000 could be expected during the next 10 years.
Spoonley said the forecast was likely to be exceeded.
"That's probably reasonably conservative even given what's happening with immigration because we've still got the returning New Zealanders, we've still got large numbers of people who are going to be entering child-bearing age in Auckland, we've still got relatively high fertility rates in parts of Auckland, particularly South Auckland. So all of those things will continue to drive the school-age population growth," he said.
"We still anticipate significant growth and the challenge will be, how do you grow the school facilities."
The Education Ministry was planning 30 new schools and 21 school expansions to meet demand, but Professor Spoonley said it was not happening fast enough.
"It's the story of Auckland really, that the infrastructure is always behind the population growth and you're always playing catch-up," he said.
Spoonley said the biggest problem was likely to be in finding capacity for more students at existing schools in the city.
"The problem is, of course, that many of the schools in the older established suburbs are full, so we're going back to the 1950s and 60s when we used to put prefabs in because of the baby boom," he said.
"Many of the new schools will have to be built out on the urban fringes of Auckland, which will present problems. There's population growth and so the new schools will cater for that, but the problem is really in more established suburbs."
The principal of one of Auckland's fastest growing new schools, Ormiston Primary, Heath McNeil, said his school had started design work for new permanent classrooms and was also getting five new modular buildings next year.
He said new schools and classrooms could and should be built faster.
"The process for starting those, particularly the permanent builds, often is waiting too long because they're waiting for the final sign-off rather than getting started with some early design work so that when the money comes on stream we're ready to go," McNeil said.
"We're waiting years to get that investment sign-off and nothing's done in those two years to help increase the pace of the design or what's needed for each of those schools."
The Education Ministry's deputy secretary sector enablement and support, Katrina Casey, said Auckland's situation was complex and challenging and at some schools demand had exceeded forecasts.
She said the ministry was speeding up the design phase for new buildings with measures including reference designs for classrooms that could be easily replicated at many school sites; expanding the delivery of modular classrooms, and having designers and contractors ready to work on school projects.
Casey said the ministry was confident sufficient classrooms would be available in the growth period to 2030.
"Since the launch of the National Education Growth Programme, we are better placed than we have ever been to forecast and manage roll-growth patterns across the country and in individual regions, including Auckland," she said.
Casey said the ministry's forecast was based on the Stats NZ high growth forecast of student numbers in Auckland growing by 58,000 from 2017-2030.
"We have commissioned some updated detailed population projections from NZ Stats which will be available later in 2021 and will enable all our forecasts to be updated," she said.
Casey said the distribution of students across Auckland was changing as a result of growth, and in some areas school rolls were increasing rapidly.
"We are tracking the lead times, extent and speed of public and private residential developments across all catchments. This allows us to adjust the required timing of, and forecast demand for, additional student places."