Masterton Town Hall and the district council offices are being assessed by a structural engineer to determine earthquake vulnerability.
A full structural engineering report is under way for the 100-year old municipal building, which has an earthquake rating of 40 per cent of the existing building code, just above the legal requirement of 34 per cent.
Masterton District Council spokesman Sam Rossiter-Stead said the council would not know the costs of strengthening the building until it received the report from the structural engineers, but that the council aims to increase the building's rating to 67 per cent following interior renovation.
He said there was a fund of $2.5million set aside for earthquake strengthening of MDC-owned buildings.
Chief executive Pim Borren said it was prudent to consider the long-term future of the building before investing in any improvements to the public and staff areas.
"We are no different to any other building owner in Masterton: we have the same responsibility to provide a safe environment that we expect from other owners and other councils around New Zealand," Mr Borren said.
"If we discover that the building is earthquake-prone and in need of significant strengthening work, then we will consider what options we have, taking into account our health and safety responsibilities."
Mr Borren said the building is 100 years old next month and is on the Wairarapa Combined District Plan Heritage Register, so the council would need to weigh up the best course of action, based on the report.
"We are holding off on some interior alterations for the time being, as it makes more sense to undertake any necessary work at the same time," he said.
Mr Rossiter-Stead said, if the building is deemed earthquake-prone, there are several buildings in Masterton that would be suitable to shift staff to on a temporary basis.