The Ministry of Education has cut its estimate for the total cost of fixing leaky schools by as much as $400 million, with a damages suit against Carter Holt Harvey one of the last remaining variables.
The cost of fixing buildings that had more serious leaks will be between $1.1 billion and $1.3b, down from a previous estimate of $1.5b, acting head of education infrastructure service Rob Campbell says.
The reduced estimate was due to "programme experience and remediation costs to date," he said in written answers to questions.
In 2013 it was believed fixing the leaky buildings could cost as much as $1.79b. About 90 per cent of the cost covers replacement of defective cladding.
The ministry embarked on court proceedings against cladding manufacturers and has since settled confidentially with building materials makers James Hardie Industries and CSR.
Mr Campbell declined to release reports written in April 2013 and January 2014 providing updates on the liability claim, saying "there is a greater public interest in the ministry getting the best outcomes from negotiations and legal action," and that talks are still continuing with Carter Holt Harvey, the remaining defendant in the product liability claim.
The ministry says nearly 1800 school buildings, out of nearly 17,000, suffered from leaks.