Mayor Phil Mauger’s office will be affected by the relocation, as will the council's meeting chamber.
City council chief executive Mary Richardson said 400 staff working on the north side of Te Hononga Civic Offices are being relocated as engineers review the seismic performance of the annex.
Engineers have advised the city council it may be required to bring the annex on the Worcester Boulevard side of Te Hononga to a higher standard.
A detailed engineers assessment is under way and is expected to be completed in three weeks.
"We are taking a precautionary approach, as safety is paramount," Richardson said.
"As a result, staff will be relocated to other parts of the main Te Hononga building or to other council facilities until we receive the report.
"Once we have the engineers findings, staff will either return back to their desks or we will start work on strengthening the annex’s connection to the main building."
Richardson said a range of relocation options for impacted staff is being developed.
"I want to thank staff, elected members and visitors to our Civic Offices for their patience and understanding. We want to minimise disruption as much as possible," she said.
"We’re in a period of uncertainty and people may have questions that we may not be able to answer until we have all the details while we wait for the outcome of the report."
Richardson said Wednesday's city council meeting has been cancelled as the chamber is unable to be used.
Most of the reports will be moved to the Finance and Performance Committee on Wednesday, May 28, at the Fendalton Service Centre.
