Secondary school principals say the Government's plan to spend $2 billion on improving school buildings over the next seven years will not be enough.
The Government is to repair the schools as part of its infrastructure plan.
But the co-vice president of the secondary schools principals association and principal of Pakuranga College, Michael Williams, says the scale of the problem is massive.
He said schools are having to deal with leaky buildings and ageing infrastructure.
"We've got schools that have taken $20-plus million to rebuild from leaky buildings. So [with] $20 million lumps, or $25 million we will go through it pretty quick."
