Giving building owners 10 years, a council submission said, "would create an execution order for many heritage/character buildings held by reluctant owners seeking to develop" and the city could lose a "considerable portion" of its character stock.
Margot McRae, of Devonport Heritage, is concerned about the changes, saying they would be used by developers and owners to destroy the suburb's character.
In Oamaru, where a cash-strapped trust owns many of the buildings in its Victorian precinct (a major tourist attraction for the North Otago town), the changes would lead to the Waitaki District Council having to demolish neglected buildings.
Property Council chief executive Connal Townsend says buildings may well need to be demolished in many parts of New Zealand because landlords do not have the money required to make them stronger to protect people.
Landlords could either knock structures down or board them up and walk away, he predicts, outlining a scenario which has haunted parts of the United States where economic downturns have left urban areas deserted.
"Owners of heritage and character properties will find the cost of earthquake strengthening prohibitive. If we want to prevent owners from walking away, leaving properties vacant and tenantless, the Government needs to address the imbalance in the tax system," said Mr Townsend, whose members own buildings worth more than $30 billion.
The Auckland Council wants a robust appeal process against owners wanting to demolish buildings at the end of the 10 years and the establishment of a national fund for heritage buildings administered by the Historic Places Trust.
It has also called for the cost of seismic refits to be deemed "repairs and maintenance" rather than "capital expenditure" for tax purposes to reduce costs for building owners.
Not everyone thinks the new rules spell gloom and doom for heritage.
Richard Goldie of architects Peddle Thorp says heritage buildings can be money-spinners and he cites the successful $1 billion Britomart restoration project as an example.
"This is the largest single heritage precinct in New Zealand, perhaps in the South Pacific," said Mr Goldie who worked on Britomart's Charter House upgrade. "Cooper and Company managed to inject life and economic use into that area. We must find active uses for our heritage buildings. The commercial success of Britomart shows it can work," he says of the expenses owners are facing.
Maurice Williamson, Building and Construction Minister, wants to know what people think about the new rules - open for public consultation until tomorrow.
"Getting the policy right involves striking a balance between the risks posed by buildings in earthquakes and the costs of strengthening or demolishing them," he says.
Under the changes, all non-residential and multi-unit multi-storey residential buildings would have to be assessed within five years.
Owners would then have 10 years to either bring them up to new standards or demolish, he says.
Relatives of Christchurch earthquake victims have expressed strong views in favour of the new regime, although some critics say many people died in structures built more recently including the CTV Building and PGG Building.
Under the Government proposal, people will have 15 years to take action - or face prosecution for owning dangerous structures.
The Historic Places Trust is strongly advocating local and central government support and incentives for strengthening earthquake-prone buildings in the form of grants, rates relief, loans and tax credits.
"Strengthening to higher standards may not be possible without some form of financial assistance from the community," a spokesman said.
*CORRECTION: Auckland Council was reported as giving owners of about 4300 quake-prone buildings 30 years to strengthen them. It says it plans to assess about 4500 buildings although exact numbers are still unknown.
The series:
Monday: The Government's big plan
Tuesday: Plight of landlords
Yesterday:The insurance issue
Today: The future for our heritage buildings
Tomorrow: How will tomorrow's buildings look and respond to earthquakes?
