Watson said this was to provide for any unforeseen costs that could crop up during the building process, with the initial pricing estimate being $15m.
The new council administration building will incorporate the library and information centre on the existing High St site.
An option to build on a corner block of Broadway and High St was ruled out due to the rising costs of redevelopment and the complexity of the site.
“One of the benefits of building on this existing site is that it can be done piece by piece, so we can continue to use the site and relocate people into the buildings,” Watson said.
He said council staff acknowledged the failings of the building and had been frustrated.
Building on the existing site would mean the council did not have to go through an additional consenting process and could stick to the Long-Term Plan budget.
Eva de Jong is a reporter for the Whanganui Chronicle covering health stories and general news. She began as a reporter in 2023.