Mr Williams said contractors had spent the past two weeks stripping slate from the building’s roof, salvaging any in good condition.
The Dunedin Prison Trust had acquired slate from Christchurch earthquake projects over the past 18 months, and would use it to replace damaged slate on the prison roof.
Restoration of the 120-year-old building was a "big-picture project", but he hoped the roof and outside architectural elements would be restored by the end of the year.
"The fleche seems to be almost a feature of John Campbell’s architecture in that I ran into another one of those at the Sunnyside Lunatic Asylum which he also designed."
Cameron Roofing specialist slatter Chris Edwards said working with slate posed "messier" challenges than working with tin.
He expected slate would start to be layed on Monday.
Mr Williams said restoration of the original shapes and forms of the building was the first step in returning it to the way it once looked.
"The board are determined to bring it back into an attractive and useful part of the city."
