‘This is the one thing that really helps your home survive’

If you do nothing else to protect your home from a wildfire, clear a 1.5-metre space around the building by removing anything that could burn.

That’s the message from a company that goes in after major wildfires to examine how homes were destroyed – and how other properties were saved.

Greg Baxter, a senior researcher at FP Innovations, presented some of the firm’s findings to representatives of 25 NWT communities in Yellowknife on Wednesday.

Baxter and colleagues carried out an examination of homes in Enterprise after the August 2023 wildfire that burned much of the South Slave hamlet.

His presentation at this week’s territorial wildfire preparedness workshop – organized by the NWT Association of Communities – also drew on data from fires in Los Angeles, West Kelowna, Jasper and the Shuswap.

From all of those fires, one recommendation stands out for Baxter.

“No flammable fuels within one and a half metres of a structure. This is critical,” he said.

“If this is the one thing that can be taken away to increase the probability of a structure surviving, it’s get rid of the materials right next to the structure – anything that can burn.”

The reason, he said, is embers will ignite flammable objects next to the home that send fire up the siding, into the soffits – the material beneath the eave connecting the walls to the roof – and then into the roof.

Baxter’s advice means any trees right next to a home should go, but conifers especially are a big risk.

Analyzing a sample of seven homes that were lost to wildfires, Baxter said all seven had untreated conifers “right next to them.”

But your deck, too, could be littered with materials that might help a wildfire reach your home.

“We saw a number of places in West Kelowna where if a structure protection crew could get there and do nothing else, it would throw materials off the deck. That saved a number of structures,” said Baxter.

From there, he said, expand to a 10-metre radius around your home and manage the vegetation in that zone – for example by avoiding having conifers within it.

If trees are spaced out and care is taken to sweep away needles and other brush, a fire’s path to your home becomes more difficult.

“We saw some really good examples of where the trees were spaced and limbed so the fire didn’t progress through there with the intensity to get to the structure,” Baxter said. That can be coupled with the use of grass and aspen instead of coniferous trees, as aspen are ordinarily less vulnerable to fire.

Baxter said data from the Enterprise fire suggested the skirting of a building should be made of fire-resistant material with no defects like holes.

“There were a number of cases where they had the skirting and there were holes. Embers go through that and then the structure burns from below,” he reported.

Wooden foundations and yard debris within 10 metres of a home were other major problems noted during the Enterprise investigation.

To gather data, FP Innovations says it analyzed fire behaviour, the weather at the time, how fuels in the area (trees, the land and so on) had been treated, and the findings of a structural fire investigator.

Baxter said the use of such an investigator marks “the first time that’s taken place in Canada.”

“Historically when wildfires move into communities, insurance companies say, ‘Well, the one wildfire caused it,’ and so it’s written off as that,” he said.

“There’s no real data collection of actually how each individual structure ignited. And so that’s where we wanted this person to find where it ignited on the structure, the materials, and then how it progressed through the structure. So that was new.”

Using an app that asked dozens of questions, investigators assessed both damaged and undamaged structures to determine what happened. Residents were also interviewed.

The research showed embers are the primary reason homes ignite, not a wall of fire advancing on the property.

“We did 117 structure assessments in all the case studies we did in 2023. There was one example of the fire actually moving up to the structure and igniting it,” Baxter said.

“All the rest were embers coming, landing, finding the weakness and igniting the structure.”

Sprinklers also made a big difference when correctly deployed and backed up by enough water to power gallons and gallons of mist. Baxter showed an example of a home that defied the odds because its sprinkler system had been carefully designed.

He said FP Innovations now has funding to carry out four more years of post-fire data collection across the country.

As a result, the firm will send opening letters in the next week to a range of communities and governments.

Editor’s note: The author is a paid moderator at the wildfire preparedness workshop where this presentation was made. Workshop organizers had no input on this article.