Demolition companies are being accused of exploiting loopholes to get approval from Civil Defence to knock down buildings.
The 98-year-old Addington Flour Mill's blending plant is the oldest in the southern hemisphere. It was lined up to be carefully taken apart - or deconstructed - but today diggers appeared at the site.
Keith Gallagher had worked at the plant until it closed three years ago. Watching what happened to the mill plant today brought him to tears.
"They were going to be taking the roof off and virtually dismantling it because there's some beautiful wood in there," he said.
But this afternoon all that remained of the building was a pile of bricks and timber.
The American Oregon timber alone had been valued at more than $600,000.
Ron Zwarst from NZ Doors said it was "absolutely criminal" for a building to be destroyed without consideration to its historic values.
Zwarst alleges a lot of the demolition is being done purely for money.
ONE News was told by the building's owner he had no knowledge of what was happening.
But officials are adamant they went through the right processes.
Civil Defence National Director John Hamilton said the deconstruction work at the grain store was approved after Urban Search and Rescue teams expressed concerns about the stability of the building. The chimney will also be deconstructed, he said.
Hamilton said as far he knew, the main mill building has not been damaged by the demolition team.
"I want to emphasise that in dealing with requirements to deconstruct or partially demolish buildings in town, every endeavour is made to contact the owners of those buildings, if that work is indeed necessary," Hamilton said at a media briefing this afternoon.
The blending plant is just one of hundreds of buildings which are being demolished throughout the CBD.
Many Christchurch residents are now worried many more buildings are being torn apart unnecessarily.