Bushfire experts have raised concerns about moves to build new suburbs to the west of Canberra – saying homes built there would be directly in the "line of fire".

The ACT government has begun an assessment of a 10,000 hectare swathe of land for future city expansion, known as the Western Edge Investigation Area.

The 20-kilometre stretch of mostly rural land runs from the existing suburbs of Belconnen south to Tuggeranong, and west to the Murrumbidgee River.

But in grim echoes of the 2003 Canberra firestorm that claimed four lives and some 500 homes, fire scientists say the city will face even greater bushfire threats from the west in the future.

They also say those suburbs would be hardest hit by fires.

They've warned the government that deadly fires are likely to become more frequent, and planners shouldn't put land sales revenue above community safety.

Growing capital expands westward

With Canberra's population set to nearly double within the next 40 years the hunt is on for new supplies of suitable suburban land.

The government has a policy of building 70 per cent of new homes within Canberra's "existing footprint", but even a modest 30 per cent suburban expansion would require tens-of-thousands of new homes in greenfield estates.

The government had previously ruled out developing land at Kowen, east of Canberra, effectively leaving the city only one direction – west – in which to expand.

But it's long been a controversial proposal – with the former Land Development Agency criticised by the ACT Auditor General for a "lack of probity" over its $43 million purchase of rural land in the west.

ACT Environment, Planning and Sustainable Development Directorate (EPSDD) deputy director Erin Brady said it would now take around a decade to complete its exhaustive studies.

"Land is not infinite in terms of land that's available for investigation, so this really is one of the big areas for us to look at to see if there is capacity," Dr Brady said.

"It's to be investigated for what are the best future uses, so that could be (environmental) offsets, rural uses ... or whether there is capacity to have residential development out there."

Suburbs in the 'line of fire'

But a panel of government-appointed independent experts has sounded alarm bells, saying it has "very serious concerns about the quality" of the government's bushfire risk assessment of the area.

The ACT Bushfire Council pointed to glaring mistakes in the government's initial technical studies, claiming consultants misread the topography and bush cover.

Its 2021-22 Bushfire Preparedness report warned Emergency Service Minister Mick Gentleman that there would be "an increased risk of catastrophic fire weather conditions" in coming years.

And, the Bushfire Council said while "95 per cent of the investigation area was mapped as suitable for urban development with Bushfire Attack Levels (BAL) of low", that appeared to be wrong.

"Council does not believe that the bushfire risk assessment appropriately considers the bushfire history, topography and vegetation systems in the investigation area or the predicted climate change scenarios for Canberra," the report said.

Dr Erin Brady said the technical study was only a preliminary assessment, and much more work would need to be done involving multiple agencies.

"Bushfire — particularly here in Canberra — is one of the big considerations for any of the planning work that we do," Dr Brady said.

Bushfire warnings 'must be taken seriously'

For decades the ACT Bushfire Council offered independent advice to government, and scrutinised government hazard reduction efforts.

Its membership was traditionally drawn from senior government executives, fire and forestry experts, planning bodies and key interest groups.

But last year the body was scrapped in favour of a "Multi Hazard" advisory council, with less emphasis on bushfire preparation and more on other natural disasters including storms.

ANU Fenner School Forestry Professor Peter Kanowski, sat on the former ACT Bushfire Council for five years after the 2003 fires.

"In my time on the Bushfire Council I found that the government was receptive to the council's advice — as it should be," Professor Kanowski said. 

"The council's focus is really a strategic one on the one hand, but also holding the government to account on the other."

Professor Kanowski said the Council's concerns about suburban expansion to the west must be taken seriously.

"We experienced that and how intense that could be on the 18th of January 2003.

"Anybody in the suburbs in the west of Canberra is potentially in the line of fire."

New planning approach needed in a changing climate

University of Canberra academic, and former Chair of the ACT's Climate Change Council, Barbara Norman said the city's increasing fire risk required a rethink of planning rules.

"We are facing a much hotter future in Canberra, a hotter and drier future, with the risk as well of sudden extreme weather events," Professor Norman said.

"The Western Investigation Area … must factor in fire risks and climate risks, so the fire ecologists need to be very much involved in our decision making."

She also warned the government not to be swayed by the prospects of massive land sales.

"There is a risk of decisions being made on revenue considerations because of the history of our revenue base in the ACT, but we need to move beyond that clearly," she said. 

"We have to remember that our planning system was inherited from the British, almost superimposed subdivisions, not thought of in terms of landform and connection to country.

"We need to be reconsidering our planning system so they factor in these risks, and don't assume that the environment will be staying the same in the future."

Western suburbs need fireproof homes

Canberra builder Dan Fitzpatrick said it was possible to build homes in higher fire risk zones.

But it required a wholistic planning approach – including smarter building design and landscaping, and better advice from fire managers.

Mr Fitzpatrick said home building rules appeared more cautious over the border than in the ACT.

For a building project near Sutton, just north of the ACT, he had been required to consult with both NSW environmental agencies and the Rural Fire Service to determine an adequate buffer zone around the house.

And importantly, he had to construct it out of fire proof materials including steel and concrete to withstand ember attack. 

"It's a delicate balance between being right amongst the trees, and future proofing for those trees maybe causing issues with bushfire in the future," Mr Fitzpatrick said.

He was concerned that the ACT government hadn't implemented sufficient building code reforms after the 2003 fires, and he had seen too many new homes constructed with incorrect materials.

"I guess the use of materials is the biggest one in the newer suburbs," he said. 

"I still see a lot of timbers and things on the outside when you're on the urban fringe right against open bushland or national park for example, and you see softwoods and things on the outside of houses, it just seems like such a no-no."

Mr Fitzpatrick said that the ACT needed an independent body to oversee the risk in bushfire prone areas.

"We definitely need a body that can oversee the bushfire risk in Canberra as it pertains to building," Mr Fitzpatrick said.

"It's in New South Wales, it's in Victoria. At the moment it's just covered under precinct codes in the ACT and it's probably not stringent enough."