Mick Johnson, who was trapped at Lilli Pilli when the fires hit, said rebuilding fast was a priority on the South Coast.

As a builder, he found bricklayers were becoming harder to come by and brick homes would take months to build.

He designed Rezicast Systems, which builders could use to put up a home's walls and trusses in as quickly as a day.

Concreters then pour slabs, frames are added, a roof put on, and windows are installed.

A whole house only took eight weeks to build, he said.

Mr Johnson said the energy rating for concrete was much higher than brick and termites didn't eat concrete so homes could be built in remote areas.

He said the cost of rebuilding was a barrier for South Coast fire victims, so the quicker the build the better.

With more people working from home now, he said a house built with a high energy rating could save money on power bills.