There are set time frames for getting the assessment done and, if required, carrying out strengthening work.
Mr Holder told the Rotorua Daily Post this week the council had received responses from the owners of around 10 per cent of those 1300 buildings, with just eight buildings confirmed as being earthquake-prone.
Speaking at Tuesday's event, Mr Holder said a building was considered earthquake prone if its structural performance was less than 33 per cent of what it should be under new building standards.
If so, it would be issued with a Dangerous Building Notice - "not something that we take pleasure in but it's required under legislation" - until it had been brought up to standard.
However, Mr Holder said banks and lending institutions were increasingly requiring buildings' strengths to be higher than 33 per cent, usually closer to 67 per cent.
"My advice is to talk to other people that have an interest in your building and see what their requirement is going to be," he said. "It might meet legislative requirements but might not meet theirs."
Bayleys Rotorua's Mark Rendell, who deals with vacant commercial buildings, agreed with that message.
He said landlords should get a report done and get their building up to above 67 per cent. That opened up the possibility of a wider range of tenants, given the use of the building could affect its risk rating.
When selling a building the first question lenders asked was what strength it was.
Mr Rendell said he knew of at least one Rotorua bank whose policy was only to lend on buildings at 67 per cent strength.
"If you're putting it on the market, get the assessment done straight away."
Thames-based engineer Bert Kroon gave attendees a rundown of the assessment and strengthening process, reassuring them engineers didn't "just pick numbers out of the air when assessing buildings" but had strict criteria to measure strength against.
For more information, go to www.rdc.govt.nz/our-services/building-and-resource-consents/EarthquakeProneBuildings.
