If no way could be found for a building to be brought up to the required structural standards, vacating the building and leaving it empty would be preferable to demolition, trust Otago-Southland area manager Owen Graham said.
The future of Dunedin's heritage buildings was so topical the trust was bringing in a specialist to give a free public talk on building strengthening.
Community groups and churches have said they will have to make some tough decisions in the next few years about historic properties as the Dunedin City Council's policy requiring owners to bring pre-1976 non-residential buildings up to defined standards within certain time frames began.
Councils nationwide are to monitor more closely long-standing requirements for property owners to make sure buildings are at least partially structurally sound in case of an earthquake.
Mr Graham warned people should not make rash decisions if assessments came back showing buildings were below the required strength.
"It might just mean a building is made of a particular material and is a certain age."
Instead, owners should take their time, get advice and consider the options.
Anyone who was concerned could contact the trust, which could advise owners about what their assessments meant and on various techniques and approaches they could take.
There were practical, cost-effective solutions for strengthening buildings, he said.
Demolition was not the only option if upgrading was unaffordable. Efforts could be made to try to sell buildings, or they could be closed and left vacant.
Owners also had years to do the work, which the trust agreed needed to be carried out.
The council's earthquake-prone building policy discourages demolition of historic buildings and points to incentive schemes - including grants and loan schemes, rates relief and free building consents for heritage buildings being strengthened.
It states that dispensation might be even be considered to avoid work that would "have a significant negative impact on heritage values or which might impact on the economic viability of re-use".
"When considering what action to take on heritage or historic buildings that are assessed as being earthquake-prone, the council will take into account the heritage values of the building in determining possible courses of action and seek to avoid demolition where possible," it says.
The issue is gaining momentum as building owners realise what is required of them.
Last week, Revenue Minister Peter Dunne acknowledged many property owners who needed to pay for earthquake-strengthening work were facing financial hardship.
He said there would have to be some Government leadership on the matter, whether that was in terms of financial assistance or a range of measures.
The same report said the Historic Places Trust estimated around 4000 heritage buildings around the country were earthquake-prone and the cost of strengthening was estimated at between $4 billion and $8 billion.
Mr Graham said he did not know how many potentially earthquake prone heritage buildings there were in Dunedin.
That would become clearer as more assessments were completed and the Royal Commission of Inquiry finding on building standards was known.
"We've got some work for a few years, I'd say."
• Win Clark, consultant structural engineer and executive officer for the NZ Society for Earthquake Engineering will give a public talk at the Otago Museum on July 19 on how stone and brick masonry buildings can be strengthened.
