City schools are "bursting at the seams" with some forced to hold several classes in the library due to a lack of classroom space.
The growth surge comes as older people move to retirement villages making way for young families to move into popular school zones, a local MP says.
Tauranga's Pillans Point School is one such school.
A major development has been approved for the primary school to remedy a growth surge in which five classes were using the school hall for their lessons.
Construction of the nine-classroom block gets under way in April and was due to be finished in time for the last term of 2016.
Pillans Point was one of a large number of Tauranga schools that were overflowing because of the influx of young families into the city. Bethlehem Primary School was in the throes of a $1.8 million project to build a seven-classroom block. The block would replace four prefabs but the rest was to cope with growth.
Pillans Point principal Matt Simeon said the school was originally to get seven new classrooms - four to replace old prefabs and three for roll growth. But it then experienced a big influx of kids at the start of last year resulting in the board of trustees asking Tauranga MP Simon Bridges for two extra classrooms. "He was quite supportive."
Mr Simeon said pretty much every school in Tauranga needed more classrooms, with Pillans Point responding to the pressure by segmenting off its hall into five classrooms. The school's roll was being boosted by a lot of ex-pats returning to New Zealand and buying in Tauranga instead of Auckland.
He said they were getting three to seven inquiries a week from families looking to move into the enrolment zone because the school had a good name, he said.
Although Pillans Point was a well-established suburb, families were buying homes from older residents who were moving into retirement villages. Another trend was for developers to remove older houses that stood in the middle of a section to create two new lots.
Mr Bridges said increasing the city's classroom capacity was a key priority for him and Bay of Plenty MP Todd Muller. "The influx of Auckland families and others was really driving roll numbers." He said people understood the pressure on schools in outer suburbs such as The Lakes and Papamoa East where new developments were taking place, but he had been surprised by growth in the inner areas where rolls were expected to be relatively stable.
Mr Bridges welcomed the changes, saying it was making Tauranga more dynamic and exciting. "We are seeing older people moving into retirement centres and villages and new young families coming in. The rolls are really increasing."
Greerton Village School was one of a number of schools that included Bellevue and Matua that were getting modern prefabs this year to cope with growth. Principal Anne Mackintosh said they were "absolutely bursting at the seams".
It resulted in the Ministry introducing an enrolment zone and agreeing to two new classrooms which will open later this year, plus a further classroom in 2017. The school library was currently home to two classes while the library was squeezed into the tiny building that was the temporary admin block.
Mrs Mackintosh said Tauranga was the victim of its own success. "We live in paradise, what would you expect."
She said the enrolment zone had been introduced because of the popularity of the school to families from outside the area. Another reason for the popularity of Greerton to young families was that its houses had "good bones".
Matua School's Board of Trustees chairman Stephen Tisch said the two learning spaces owned by the board that were supposed to be used for arts and the performing arts were instead being used as classrooms because of the pressure from roll growth.
While the board believed the school was entitled to two more classrooms, the Ministry had only awarded one more for this year. "The Ministry is benefiting from this school being proactive and investing in extra spaces to fulfil the requirements of the curriculum," he said.