Hawkins Construction is seven months away from finishing the new East building in the $1 billion Britomart project.
Chris Hunter, Hawkins' chief executive, said the 12-level building would be completed next April and construction had reached level nine.
Hawkins started on the site at the intersection of Britomart Place and
Galway St behind the old Wharf Police Station in July last year. About 20 per cent of the building is not leased but head tenants are Westpac and Ernst & Young.
Developer Cooper and Company is searching for more tenants in an attempt to get full occupancy when the building opens.
A large central atrium has been developed in the middle of the new building and its roof will be clad with the transparent ETFE (ethylene tetrafluoroethylene) which is also being used on the new South Stand at Eden Park.
Hunter said the East job in the CBD was extremely unusual and presented challenges specific to the site.
"Structural steel columns that support the new building are directly above the existing structural walls of the Britomart train station. The Britomart was built to allow construction above it at a further stage.
"All structural steel columns in the new building sit on elastomeric or rubber bearings to isolate the building from vibrations caused by the trains below," Hunter said.
The steel on the structure is complete and fitouts, roofing and cladding is under way. Glass on the exterior will be finished by November.
A "walking street" has been created through the middle of the building, opened up via the glass atrium. This will allow access to and from the Britomart transport centre.
The building will be divided into two parts when finished: East 1 will be Westpac on Takutai Square and East 2 will be the Ernst & Young Building.
