A survey aimed at revealing the real extent of the leaky-school problem has identified 580 damaged buildings at 245 campuses - and it's still far from being finished.
Early results from the national defective-buildings survey, released exclusively to the Herald under the Official Information Act, indicate the country's leaky schools will cost the Government around $1.1 billion to fix.
Of that, $175 million is needed for urgent repair work and a further $300 million is needed to replace relocatable classrooms.
Until now, the Government has been relying on figures from a 2010 study of 199 Auckland schools which estimated it would cost about $1.2 billion to permanently fix leaky buildings.
But, while it had an estimate on cost, the Ministry of Education had no real idea of the extent of the problem, so the minister ordered a $5 million survey of all school property built or modified since 1994.
That survey started in June and so far 3249 of the 5500 buildings that need to be assessed at 1647 schools have been checked. Of those, 580 at 245 schools have been identified as defective or potentially defective.
A further 907 schools are still to be assessed so the number of leaky buildings is only expected to increase.
According to the ministry, repair work is under way on 220 leaky schools but it is not clear how many of those are also included in the survey, which only talks about remediation being completed at 22 schools.
Education Minister Anne Tolley said it would be a huge expense fixing leaky schools - and one that would add to pressure on the budget for school buildings.
"The report confirms we are on course for a massive bill for leaky schools, which could have been reduced had the previous Labour Government addressed this issue during its nine years in office.
"We are determined to fix these schools, but much of the funding is going to have to come from baseline funding for school capital over the next few years."
The Government allocated a capital injection of $82 million specifically for leaky schools in the 2010 Budget.
Mrs Tolley said expenditure was expected to increase to $100 million in the 2011-12 year.
"This is yet another pressure on our budget for school buildings which is why the $1 billion that National plans to invest from the Future Investment Fund is so important."
Ian Leckie, president of education sector union NZEI, said it was always known that leaky schools were a problem but he was surprised to hear just how many buildings were affected.
He urged the Government to think about how it was funding repairs to the leaky buildings, saying that taking money needed for other building, maintenance or school projects would only create problems down the track.
"In the wisdom of good planning I'm hoping one isn't at the expense of another."
Glen Innes Primary School hall cost $345,000 to build in 1999 but cost around $760,000 to fix after it was found to be leaky in 2003.