The windows have been replaced and horizontal cedar boards are being placed across part of the front of the building, softening the typically 1960s bunker-like style, and the interior is being renovated and developed as office space.
Mrs Roberts says they had wanted to maintain the integrity of the 1960s minimalist architecture but enhance the building so it was a positive addition to the CBD streetscape.
"We are really pleased with the architect's response to the brief and with the professionalism and quality of workmanship by all the contractors. The main building is not quite heritage yet, but it will be one day and we felt we had a responsibility to honour that."
Mrs Roberts says the other administrative building on the site will be developed in response to tenant interest and requirements.
All possibilities would be considered, including apartments.
The couple live in central Otago but Mrs Roberts grew up in Whangarei and retains close ties with the north.
All the work on the site has gone to Whangarei firms, including Chris Howell of Main4 Architects, DB Interiors, ChillTec, Kerr Construction and numerous sub-contractors.