Leading architect and designer Chris Moller has slammed the decision to demolish the Aniwaniwa Visitors' Centre at Lake Waikaremoana, describing it as "outrageous".
Mr Moller, who fronts the TV3 programme Grand Designs, was speaking on Kim Hill's RNZ show when he described the decision by the Department of Conservation to pull down the 40-year-old John Scott-designed building as showing a lack of understanding for Mr Scott's work.
"The Scott family is devastated and rightly so," Mr Moller said.
"It is one of his great works - I am quite upset about it."
Mr Moller, who described Mr Scott as a mentor, said the Institute of Architects had been "one hundred percent" behind saving the building which was now in the last stages of coming down.
A DoC spokesperson said despite recent bad weather the demolition, which got the green light at the start of the month, was now only two to three weeks away from being wrapped up.
The Institute of Architects had written to the Auditor-General, the Ombudsman, Te Urewera Board and Chris Finlayson as Minister Responsible for Treaty Settlements.
A spokesman had said they believed poor information had been used to justify what they declared was "a poor decision".
There had been claims DoC had failed to follow government tendering processes for the demolition with DoC operations manager responding by saying the two contracts involved, which included the salvaging of timbers, were not subject to the legislation as both were under $100,000.
Mr Moller said he was disappointed that the fact it was a registered category 1 building under historic places was not acknowledged.
He was also sceptical about how the department had approached the whole issue, saying "excuses" from DoC that it would have cost $5 million to repair were "absolutely not true".
He added that supposed leaky building issues were more to do with rigorous maintenance not being upheld and that earthquake resistance figures were not right.
"A bundle of issues need to be addressed," he said.
"To maintain architectural and cultural heritage."
He said Mr Scott contributed to the nation's architectural landscape in a very positive way and said it was sad to see what he called a positive part of New Zealand's history come down.