David Aitken remembers the helplessness of being trapped in his New South Wales south coast home during the Black Summer bushfires of 2019.
His plan to evacuate from the house he built 3 kilometres south-west of Moruya was undone by fallen trees and road closures that blocked the route he could have used to escape.
"It was frightening. The smoke was just pouring over the top. The whole forest was blazing around us," he said.
Mr Aitken and his house survived but the experience prompted him to build a bushfire bunker.
The more than 7-tonne concrete bunker has 10-centimetre-thick concrete walls and can fit six adults. It's built into the ground and designed as a last resort for short use during the crucial moments as a fire is passing directly overhead.
"Now I feel so good. It's not far to run from the bunker to the house," Mr Aitken said.
"You don't panic. There's some place where you can go down and quietly sit out a fire."
He said recent fires in Hawaii and California that destroyed entire townships made him grateful to have somewhere to flee a fire.
"Whole villages have gone up. You're not protected, just because you've evacuated into an area," he said.
Growing interest, but need for regulation
Bunker manufacturer Anthony Tratt, who is CEO of Wildfire Safety Bunkers, said his company had continued to grow since opening in 2010.
The bunkers retail from $20,000.
"There was a massive spike after Black Summer," Mr Tratt said.
The business is one of four accredited bushfire-bunker providers in Victoria.
However, the increased demand for bunkers at Mr Tratt's business highlights a lack of a national framework for their installation.
Every state and territory has a different approach, according to Adelaide Law School's Phillipa McCormack.
"The problem is we don't have a consistent, clear and streamlined set of rules," she said.
Dr McCormack said not enough had been done to create a national approach to bushfire bunkers, despite a former intelligence chief three years ago saying political inaction would cost lives.
Part of the issue, according to Dr McCormack, is authorities are hesitant to endorse bunkers as a bushfire survival strategy.
"What the authorities cannot say is, 'Buy this, you definitely won't die,'" she said.
"Catastrophic fire – you can't guarantee safety from that."
In a statement, a spokesperson for the NSW Rural Fire Service said bunkers weren't a substitute for a bushfire safety plan.
"Inadequately designed, badly located and poorly maintained private bushfire shelters are extremely dangerous," the spokesperson said.
"It's important to have a well-planned and discussed bushfire survival plan and of course, the safest place to be is away from the fire."
Deciding themselves
Dr McCormack said the complicated approval process meant people who wanted bunkers installed them anyway – sometimes building makeshift shelters themselves.
In 2023, a Tasmanian resident was ordered to remove a bunker from their property after a court case brought by their local council because it was not installed according to regulations.
A royal commission after Victoria's Black Saturday in 2009 found many people sheltered in unsuitable locations.
"We could make it more streamlined and accessible for ordinary people to put in place a shelter that's going to keep them safer than their lawn or their toilet or their car," Dr McCormack said.
"The bunker isn't your first plan for safety. It's your last resort if other plans fail.
"The thing is, other plans will fail.
"We really need a plan for those people who are looking to keep themselves safe."
Dr McCormack said discussions about the need for evacuation and a bushfire safety plan could be incorporated into the building approval and purchasing process.
Currently Victoria is the only state with a clear pathway outlining what a bunker is and what is needed for it to be approved.
Dr McCormack said there was an urgent need for a national approach that could follow the Victorian model.
"We know [future fires] are going to come more frequently, they're going to be more severe, they're going to burn in places where they haven't burned before," she said.
"The next catastrophic fire season is any year now, and we need to give people a chance."