Many homes supposedly built to withstand bushfires are highly likely to burn to the ground due to non-compliant modifications by property owners, a seminar has heard.

Justin Leonard, who leads CSIRO’s Bushfire Urban Design team, gave the Risk Frontiers Annual Seminar an insight into the fire at Wye River and Separation Creek on Victoria’s Great Ocean Road in December last year.

More than 100 homes were destroyed, but thanks to advance warnings and effective evacuation nobody was killed.

Seven homes built to the latest bushfire standards were affected by the blaze, with three surviving and four destroyed. This was an improvement on the 80% loss rate across the fire-affected area, but Mr Leonard believes it should have been even better.

Some homes were incorrectly signed off by building surveyors as meeting the standards, and others featured non-compliant modifications made at later stages.

Homeowners routinely installed wooden decking or retaining walls, and stored flammable materials underneath their properties.

“Regulations aren’t going to get us that far on their own,” Mr Leonard told the forum in Sydney.

“But a combination of regulations, common sense and good occupier behaviour could work.”

Mr Leonard told insuranceNEWS.com.au it’s vital the residents of Wye River and Separation Creek “get it right next time”, because they may not get such early warnings.

“The township is very steep and difficult to navigate,” he said. “They have to get a better loss proportion next time. There are roads where, if a house is on fire, it is going to prevent you escaping either on foot or in a vehicle.”

He believes homeowners should be supplied with a booklet or user manual outlining long-term obligations.

“The absence of such a document is a fundamental flaw,” he said.