The government has now revealed it approved an extra $11.5 million dollars to fix one of four leaky and rotting buildings at Middlemore Hospital.
RNZ has revealed four big and relatively new Middlemore Hospital buildings are affected, including the children's hospital and the nearby Manukau Superclinic.
Documents obtained under the Official Information Act show the decay is so bad it is in danger of breaching the walls, and could contaminate the air and make staff and patients sick.
The Health Minister's office said yesterday David Clark could not comment.
But today the Minister announced that early this week he'd signed off funding for re-cladding work on the Scott Building which has timber framing decay and mould.
The extra injection of funds takes the total cost of the remediation project to $27.5 million.
Dr Clark said the health board's advice was that patient safety is not at risk as long as any rot and mould are contained in the walls.
The Health Minister was not told the full extent of the leaky and rotting buildings at Middlemore Hospital.
Yesterday he announced an extra $11.5 million to fix one of the buildings, but it's been revealed he wasn't told about three other badly damaged buildings.
Documents released to RNZ News under the Official Information Act show the Counties Manukau district health board has known about critical problems at its Kidz First hospital, the Scott and McIndoe buildings and the Manukau Superclinic - since 2012 in some cases.
Dr Clark said he met with the DHB last week and was only told about the Scott Building.
He said he would be having a frank conversation with the board's chair and will be seeking an explaination.
The documents showed the hospital's management has known since 2012 about problems with two of the buildings, and discovered issues with two others in 2013 and 2014 - but has not fixed them.
Counties Manukau DHB said in a report that it has put safety measures in place, including monitoring at one of the buildings, but it has not detailed exactly what measures and is refusing to be interviewed.
Efeso Collins is the Auckland councillor representing the Manukau ward, which includes Middlemore Hospital.
He told Morning Report the first he had heard about the rot was on RNZ this morning and was he was deeply concerned.
"We're sending sick kids from damp homes in South Auckland to a damp hospital.
"And the fact that the DHB is saying nothing, isn't talking to media ... it's deeply concerning.
Mr Collins said it was very disappointing for his area where there were high rates of rheumatic fever and asthma.
"Slowly what we're seeing is this complete erosion of peoples' confidence in a health service that we've depended on for so long."
He said he would contact the DHB board this morning to find out why the information has only came to light now, six years after they first became aware of the issue.
Mould 'like asbestos dust'
The hospital buildings should have been vacated as soon as dangerous mould was found, a lawyer who has handled hundreds of leaky building cases said.
"[The mould] stachbotrys is a very significant problem. It's effectively like asbestos dust and it can get into your lungs and cause all sorts of respiratory problems," Auckland lawyer Paul Grimshaw said.
"I think as soon as the management was made aware of this back in 2012 they ought to have taken immediate steps to get these kids and these patients out.
"The delay seems to be inexcusable in this case."