The author of a new book about New Zealand’s leaky building disaster says the previous estimated cost to the country is wrong and is probably twice the amount.
Previous estimates have suggested the cost was between $11 billion and $23 billion dollars, however, Peter Dyer says a report that was never released by the Government highlights a discrepancy between what the original estimate was, and that the figure was probably more like $47 billion.
Mr Dyer wrote the book Rottenomics which talks about the "real cost" of the leaky building disaster.
He says a Government-commissioned report in 2014 that was never released didn’t ask for a dollar estimate and only asked about the number of leaky homes.
He says the number of leaky homes estimated in that report was about 174,000.
It was the second of two reports that the Government commissioned, the first one was commissioned in 2009, a Price Waterhouse Coopers report.
Mr Dyer says the 2009 report did include a dollar estimate.
“What I did was I took the cost to dwelling ratio to the number of houses and applied that conservatively to the number of houses in the second report and so that’s how I came up with that figure," he told TVNZ 1's Breakfast.
He says that figure turns out to be somewhere in the vicinity of $47 billion dollars.
“The authors of the first report used a different methodology from the authors in the second report and they covered a broader time period for one thing,” Mr Dyer says.
He says the authors between the two reports looked at different things and the variance accounted for the discrepancy.