Owners will then have between 12.5 and 25 years to do what strengthening work is required.
"We've got a bit of time but that will come rushing at us," council's building control team leader Greg Hoobin said.
Trevor Goodwin from council's earthquake prone buildings taskforce said owners should contact council quickly and get help through the process.
"The offer is there for help but ultimately these things will have to be complied with."
Building owners could have access to both local and national financial support.
Mike Frew of the Ministry of Culture and Heritage spoke about the Heritage EQUIP fund which can pay for up to 50 per cent of the work needed to get a buildings to 34 per cent of the new building standard (NBS).
"It is a relatively substantial support package that is available.
Frew said owners faced two barriers to doing seismic upgrades - information and cost - and the EQUIP fund was there to help.
The was $6million currently left in it but this was being reviewed.
He spoke about two heritage buildings - the Ford workshop in Lower Hutt and National Tobacco Company in Napier - which had received $10,000 and $270,000 respectively.
Building need to listed with Heritage New Zealand or in a district plan and need to be privately owned for applications to be made.
"The stakes are pretty high and the stakes are really what the heritage EQUIP fund was set up to support on a national scale," Frew said.
"I'd love to Whanganui taking the opportunity and it would be awesome to see the fund oversubscribed simply through Whanganui applications, to be frank."
This funding could tie in with the council's new heritage grant scheme which can fund work which preserves or enhances the heritage look of buildings, council's principal planner Hamish Lampp said.
He also offered his support and advice to building owners.
Mike Scott from engineering consultancy Miyamoto, which does seismic upgrade planning, said his company were looking at cost effective solutions to problems.
In the United States and Japan, two countries with high seismic activity, it was getting harder to get insurance and owners needed to insure themselves by having seismic work done on their buildings.
"There's is no better time that now. It is never going to get cheaper."
